When working with portable cables, its crucial to consider a wide range of variables for them to work correctly. For example, the type of cable connectors or the cables exposure to certain weather types. Thankfully, theres a place where you can find all you need to do cable prepping and make any connection happen.
Click here to get more.
1.Power Cable & Portable Cord
First, its important to define them properly.
A Portable cord (also called an extension cord or flexible cord) is a flexible cable with one or more insulated conductors inside a rubber insulation cover. Operators commonly use these cables for electrical purposes in temporary connections in extreme environments thanks to enduring abrasive materials and constant flexing. Although these cables don´t come with plugs at the end of the cord, portable cords are preferred over other cables. Especially when wiring commercial or industrial facilities. They are perfect for connecting all kinds of appliances, portable tools, small motors, and even industrial machinery.
On the other hand, manufacturers designed power cables, especially for permanent, durable connections. Operators and installers use them for electrical, industrial, and commercial usage, with power cables often seen on mining applications, among others. Whether its for electrical, telecommunication, or even internet connection purposes, power cords and portable cables are everywhere. These cables have so much to offer users in terms of durability, usability, and price/quality ratio.
2. Types of Portable Cable
Portable CableSOOW/SJOOW Portable Cord
These portable cable cords possess a heavy-duty service cord. As the jacket hardens under the application of heat, it protects the cable of almost everything. This includes aging, water, abrasion, ozone, and even sunlight exposure.
Usually, operators use SOOW and SJOOW cables for most electrical power connections as they are flexible and able to endure plenty of environmental variables. As the most common application is for industrial applications, a junior service cord, like the SJOOW, is often rated for 300V service. On the contrary, the SOOW portable cord is preferred for 600V service.
Flexible power cables like the SOOW and SJOOW come in 20 to 1,000-ft lengths. This makes them the perfect choice for indoor or outdoor applications, enduring up to 194ºF environments.
Portable CableW Portable Cord
W portable cords have a rubber outer coat that resists both weather and water, making this type of cable a heavy-duty service cord. It resists impact and abrasion on top of other environmental conditions. The strong core inside the cable ensures the flexibility and durability it needs to perform the right way.
Unlike SOOW and SJOOW cables, the W portable cable is perfect for temporary higher voltage service, supporting up to V. This turns the W portable cable into the right cable to use on drills, locomotives, pumps, cranes, and other heavy machinery.
Portable CableSTOW/SJTOW Portable Cord
Best used as an extension cable, especially to portable tools, STOW and SJTOW portable cables are the best cord to power portable lights, washing machines, and other maintenance appliances alike. They have a thermoplastic jacket capable of resisting weather, water, and oil at all times. STOW and SJTOW cables are less flexible than other portable cords; however, they also work for heavy and junior services.
Portable CableSEOW Portable Cord
The TPE outer jacket that covers the SEOW portable cord makes this cable resistant to weather, oil, and water. In addition, the TPE allows it to endure lower temperatures; however, is not as durable as other portable cables. It works perfectly to power electrical equipment and construction tools, among others.
Pendant Drop Portable Cord
The Pendant Drop Portable Cord is a type of ceiling cable that hangs from the ceiling to provide a temporary power supply to machines of all kinds, especially used to work with handling and lifting equipment, including hoists or cranes.
Portable CableSC Portable Cord
Operators commonly use this heavy-duty cable as an entertainment or stage cable and it comes with a single conductor within its rubber jacket. SC Portable Cord is water, abrasion, crushing, ozone, and even solvent-resistant. In addition, people mainly use SC portable cords in TV broadcasts, communication vehicles, theater stage lighting, and even sound systems.
3. Portable CableIndustrial Power Cable Assemblies at Cloom
Due to their ability to carry higher voltage levels, industrial power cables are thicker, more robust, and overall stronger than the ones used for residential purposes. Its construction allows them to be highly flexible and sturdy for industrial applications.
Type W Power Cable Assemblies
W Power Cable Assembly is flexible, trustworthy, and resistant to abrasions and impacts of all kinds. Furthermore, its perfect for any heavy-duty industrial application and offers the chance to supply both portable and temporary power.
Type PPE Power Cable Assemblies
The PPE Power Cable Assembly is the one with maximum flexibility and safe-handling features while resisting sunlight and water exposure. On top of that, it works with ACs, oil drills, power extension, mining, and more, providing portable and temporary power at all times.
Portable Cable50A Twist-Lock Spider Box Assemblies
Being the perfect choice for recovering any kind of disaster, these box assemblies have industrial-level blade connectors that lock. These blade connectors allow the cables to work properly. In addition, these cables resist impact, chemicals, and even sunlight.
Portable Cable2/5 Banded Cable Assemblies
Its outer cover is able to resist everything from moisture to flames, oils, solvents, and even acids. In addition, it also resists abrasion, crushing, and even ozone, making this type of cable assembly perfect for distribution panels and lighting applications on both entertainment and industrial facilities.
4. Entertainment Power Cable Assemblies at Cloom
This type of cable assemblies is often used for big, important entertainment-oriented facilities like concert venues, TV stations, movie sets, theatres, or sports stadiums. Their main feature is that these cable assemblies lower the chances of experiencing the power and electrical loss.
Portable CableSocapex 19-Pin Extensions, Break-Outs, and Break-Ins
The Socapex 19-Pin cable assembly has a high weight-strength ratio. In addition, it is perfect to perform simple wiring and maintenance on theatres, movie sets, and TV stations. This cable assembly works fine to lighting any stage with rugged connector requirements.
Portable CableSC Feeder Cable Assemblies
The SC Feeder offers resistance to sunlight, abrasions, chemicals, heat, acids, flame, and even water. In addition, its flexible, durable, and can be used both outdoors and indoors for theatres, TV, and movie sets.
Portable CableQuad Stringer Assembly Extensions
The Quad Stringer Assembly Extensions resist water, electric shock, and corrosion wonderfully, making this cable assembly the one for job sites and construction sites.
Stage Pin Assemblies
Its design allows the Stage Pin Assembly the ability to prevent infiltrations and absorb impacts. In addition, its easy to handle thanks to its nice insulation and works great for lighting applications.
Conclusion
Also, there are plenty of industry-standard letter codes thatll help you choose the correct cable for your cable assemblies needs. Considering the vast array of environmental conditions, there are those that range from 3/64 Insulation | 18-10 AWG to 18-2 AWG | 2 or more conductors. In addition, there are portable cables with Neoprene Jacket, PVC Jacket, or colored jacket. These physical properties influence how a standard cord will work.
If you are looking for a trustworthy portable cable and power cord reseller, contact us. We can provide any help and supply you need.
400.1 Scope
This article covers general requirements, applications, and construction specifications for flexible cords and flexible cables
400.2 Other Articles
Flexible cords and flexible cables shall comply with this article and with the applicable provisions of other articles of this Code.
400.3 Suitability
Flexible cords and flexible cables and their associated fittings shall be suitable for the conditions of use and location.
(B) Ultimate Insulation Temperature
In no case shall conductors be associated together in such a way with respect to the kind of circuit, the wiring method used, or the number of conductors such that the limiting temperature of the conductors is exceeded.
(A) Standard Markings
Flexible cords and flexible cables shall be marked by means of a printed tag attached to the coil reel or carton. The tag shall contain the information required in 310.8(A) . Types S, SC, SCE, SCT, SE, SEO, SEOO, SJ, SJE, SJEO, SJEOO, SJO, SJT, SJTO, SJTOO, SO, SOO, ST, STO, STOO, SEW, SEOW, SEOOW, SJEW, SJEOW, SJEOOW, SJOW, SJTW, SJTOW, SJTOOW, SOW, SOOW, STW, STOW, and STOOW flexible cords and G, G-GC, PPE, and W flexible cables shall be durably marked on the surface at intervals not exceeding 610 mm (24 in.) with the type designation, size, and number of conductors. Required markings on tags, cords, and cables shall also include the maximum operating temperature of the flexible cord or flexible cable
(B) Optional Markings
Flexible cords and cable types listed in Table 400.4 shall be permitted to be surface marked to indicate special characteristics of the cable materials. These markings include, but are not limited to, markings for limited smoke, sunlight resistance, and so forth.
400.12 Uses Not Permitted
Flexible cord and cable shall also be permitted to have one connection to the building surface for a suitable tension take-up device . Length of the cord or cable from the supply termination to the take-up device shall be limited to 6' (1.83 m). Strain relief cable grips shall be provided for the cord or cable at the equipment terminations.
Exception to (4): Flexible cord and flexible cable shall be permitted to be attached to building surfaces in accordance with 368.56(B) and 590.4
Exception to (5): Flexible cords, flexible cables , and power supply cords shall be permitted if contained within an enclosure for use in other spaces used for environmental air as permitted by 300.22(C)(3)
Informational Note: For proper application see UL 817, Cord Sets and Power-Supply Cords , and UL 62, Flexible Cords and Cables
Unless specifically permitted in 400.10 , flexible cords, flexible cables , cord sets, and power supply cords shall not be used for the following:
400.13 Splices
Flexible cord shall be used only in continuous lengths without splice or tap where initially installed in applications permitted by 400.10(A) . The repair of hard- service cord and junior hard- service cord (see Trade Name column in Table 400.4 ) 14 AWG and larger shall be permitted if conductors are spliced in accordance with 110.14(B) and the completed splice retains the insulation, outer sheath properties, and usage characteristics of the cord being spliced.
400.16 Overcurrent Protection
Flexible cords not smaller than 18 AWG, and tinsel cords or cords having equivalent characteristics of smaller size approved for use with specific appliances , shall be considered as protected against overcurrent in accordance with 240.5
400.20 Labels
Flexible cords shall be examined and tested at the factory and labeled before shipment.
(A) Conductors
The individual conductors of a flexible cord or flexible cable shall have copper flexible stranding and shall not be smaller than the sizes specified in Table 400.4
400.22 Grounded-Conductor Identification
One conductor of flexible cords that is intended to be used as a grounded circuit conductor shall have a continuous marker that readily distinguishes it from the other conductor or conductors. The identification shall consist of one of the methods indicated in 400.22(A) through (F).
(A) Colored Braid
A braid finished to show a white or gray color and the braid on the other conductor or conductors finished to show a readily distinguishable solid color or colors.
(B) Tracer in Braid
Exception: In the case of Types C and PD and cords having the braids on the individual conductors finished to show white or gray. In such cords, the identifying marker shall be permitted to consist of the solid white or gray finish on one conductor, provided there is a colored tracer in the braid of each other conductor.
A tracer in a braid of any color contrasting with that of the braid and no tracer in the braid of the other conductor or conductors. No tracer shall be used in the braid of any conductor of a flexible cord that contains a conductor having a braid finished to show white or gray.
(C) Colored Insulation
For jacketed cords furnished with appliances , one conductor having its insulation colored light blue, with the other conductors having their insulation of a readily distinguishable color other than white or gray.
Exception: Cords that have insulation on the individual conductors integral with the jacket.
The insulation shall be permitted to be covered with an outer finish to provide the desired color.
A white or gray insulation on one conductor and insulation of a readily distinguishable color or colors on the other conductor or conductors for cords having no braids on the individual conductors.
(D) Colored Separator
A white or gray separator on one conductor and a separator of a readily distinguishable solid color on the other conductor or conductors of cords having insulation on the individual conductors integral with the jacket.
(E) Tinned Conductors
One conductor having the individual strands tinned and the other conductor or conductors having the individual strands untinned for cords having insulation on the individual conductors integral with the jacket.
(F) Surface Marking
One or more ridges, grooves, or white stripes located on the exterior of the cord so as to identify one conductor for cords having insulation on the individual conductors integral with the jacket.
(A) Colored Braid
A braid finished to show a continuous green color or a continuous green color with one or more yellow stripes.
(B) Colored Insulation or Covering
For cords having no braids on the individual conductors, an insulation of a continuous green color or a continuous green color with one or more yellow stripes.
(A) Conductors
The conductors shall be 12 AWG copper or larger and shall employ flexible stranding.
400.35 Fittings
Connectors used to connect lengths of cable in a run shall be of a type that locks firmly together. Provisions shall be made to prevent opening or closing these connectors while energized . Suitable means shall be used to eliminate tension at connectors and terminations.
402.1 Scope
This article covers general requirements and construction specifications for fixture wires
402.3 Types
Informational Note: Thermoplastic insulation may stiffen at temperatures lower than 10°C (+14°F). Thermoplastic insulation may also be deformed at normal temperatures where subjected to pressure, such as at points of support.
Table 402.3 Fixture Wires Name Type Letter Insulation AWG Thickness of Insulation Outer Covering Maximum Operating Temperature Application Provisions mm mils Heat-resistant rubber-covered fixture wire flexible stranding FFH-2 Heat-resistantFixture wires shall be of a type listed in Table 402.3, and they shall comply with all requirements of that table. The fixture wires listed in Table 402.3 are all suitable for service at 600 volts, nominal, unless otherwise specified.
402.6 Minimum Size
Fixture wires shall not be smaller than 18 AWG.
(A) Method of Marking
Thermoplastic insulated fixture wire shall be durably marked on the surface at intervals not exceeding 610 mm (24 in.). All other fixture wire shall be marked by means of a printed tag attached to the coil, reel, or carton.
(B) Optional Marking
Fixture wire types listed in Table 402.3 shall be permitted to be surface marked to indicate special characteristics of the cable materials. These markings include, but are not limited to, markings for limited smoke, sunlight resistance, and so forth.
(C) Switches in Tub or Shower Spaces
Switches shall not be installed within tub or shower spaces unless installed as part of a listed tub or shower assembly.
(A) Single-Throw Knife Switches
Single-throw knife switches shall be placed so that gravity will not tend to close them. Single-throw knife switches, approved for use in the inverted position, shall be provided with an integral mechanical means that ensures that the blades remain in the open position when so set.
(B) Double-Throw Knife Switches
Double-throw knife switches shall be permitted to be mounted so that the throw is either vertical or horizontal. Where the throw is vertical, integral mechanical means shall be provided to hold the blades in the open position when so set.
(C) Connection of Switches
Exception: The blades and terminals supplying the load of a switch shall be permitted to be energized when the switch is in the open position where the switch is connected to circuits or equipment inherently capable of providing a backfeed source of power. For such installations, a permanent sign shall be installed on the switch enclosure or immediately adjacent to open switches with the following words or equivalent: WARNING LOAD SIDE TERMINALS MAY BE ENERGIZED BY BACKFEED. The warning sign or label shall comply with 110.21(B)
Single-throw knife switches and switches with butt contacts shall be connected such that their blades are de- energized when the switch is in the open position. Bolted pressure contact switches shall have barriers that prevent inadvertent contact with energized blades. Single-throw knife switches, bolted pressure contact switches, molded case switches, switches with butt contacts, and circuit breakers used as switches shall be connected so that the terminals supplying the load are de- energized when the switch is in the open position.
404.7 Indicating
Where these switch or circuit breaker handles are operated vertically rather than rotationally or horizontally, the up position of the handle shall be the closed (on) position.
Exception No. 1: Vertically operated double-throw switches shall be permitted to be in the closed (on) position with the handle in either the up or down position.
Exception No. 2: On busway installations, tap switches employing a center-pivoting handle shall be permitted to be open or closed with either end of the handle in the up or down position. The switch position shall be clearly indicating and shall be visible from the floor or from the usual point of operation.
General-use and motor-circuit switches circuit breakers , and molded case switches, where mounted in an enclosure as described in 404.3 , shall indicate, in a location that is visible when accessing the external operating means, whether they are in the open (off) or closed (on) position.
(C) Multipole Snap Switches
Informational Note: See 210.7 for disconnect requirements where more than one circuit supplies a switch.
A multipole, general-use snap switch shall not be permitted to be fed from more than a single circuit unless it is listed and marked as a two-circuit or three-circuit switch.
(A) Faceplates
Faceplates provided for snap switches, dimmers, and control switches mounted in boxes and other enclosures shall be installed so as to completely cover the opening and, where the switch is flush mounted, seat against the finished surface.
(C) Construction
Metal faceplates shall be of ferrous metal not less than 0.76 mm (0.030 in.) in thickness or of nonferrous metal not less than 1.02 mm (0.040 in.) in thickness. Faceplates of insulating material shall be noncombustible and not less than 2.54 mm (0.100 in.) in thickness, but they shall be permitted to be less than 2.54 mm (0.100 in.) in thickness if formed or reinforced to provide adequate mechanical strength.
(A) Surface Type
1/2 in.) from the surface wired over.General-use snap switches , dimmers, and control switches used with open wiring on insulators shall be mounted on insulating material that separates the conductors at least 13 mm (in.) from the surface wired over.(B) Box Mounted
Flush-type general-use snap switches , dimmers, and control switches mounted in boxes that are set back of the finished surface as permitted in 314.20 shall be installed so that the extension plaster ears are seated against the surface. Flush-type devices mounted in boxes that are flush with the finished surface or project from it shall be installed so that the mounting yoke or strap of the device is seated against the box. Screws used for the purpose of attaching a device to a box shall be of the type provided with a listed device , or shall be machine screws having 32 threads per inch or part of listed assemblies or systems, in accordance with the manufacturer's instructions.
(A) Isolating Switches
Knife switches rated at over amperes at 250 volts or less, and at over amperes at 251 to volts, shall be used only as isolating switches and shall not be opened under load.
(B) To Interrupt Currents
To interrupt currents over amperes at 250 volts, nominal, or less, or over 600 amperes at 251 to volts, nominal, a circuit breaker or a switch listed for such purpose shall be used.
(A) Alternating-Current General-Use Snap Switch
This form of switch shall only be used on ac circuits and used for controlling the following:
(B) Alternating-Current or Direct-Current General-Use Snap Switch
This form of switch shall be permitted on either ac or dc circuits and used only for controlling the following:
(C) CO/ALR Snap Switches
Snap switches directly connected to aluminum conductors and rated 20 amperes or less shall be marked CO/ALR.
(D) Alternating-Current General-Use Snap Switches Rated for 347 Volts
This form of switch shall not be rated less than 15 amperes at a voltage of 347 volts ac, and they shall not be readily interchangeable in box mounting with switches covered in 404.14(A) and (B). These switches shall be used only for controlling any of the following:
(A) Ratings
Switches shall be marked with the current, voltage , and, if horsepower rated, the maximum rating for which they are designed.
404.26 Knife Switches Rated 600 to Volts
Auxiliary contacts of a renewable or quick-break type or the equivalent shall be provided on all knife switches rated 600 to volts and designed for use in breaking current over 200 amperes.
(C) Receptacles for Aluminum Conductors
Receptacles rated 20 amperes or less and designed for the direct connection of aluminum conductors shall be marked CO/ALR.(F) Receptacle With USB Charger
A 125-volt 15- or 20-ampere receptacle that additionally provides Class 2 power shall be listed and constructed such that the Class 2 circuitry is integral with the receptacle
(6) Weather-Resistant Receptacles
Weather-resistant receptacles shall be provided where replacements are made at receptacle outlets that are required to be so protected elsewhere in this Code.
(B) Boxes That Are Flush
Receptacles mounted in boxes that are flush with the finished surface or project therefrom shall be installed such that the mounting yoke or strap of the receptacle is held rigidly against the box or box cover.(D) Position of Receptacle Faces
Exception: Listed kits or assemblies encompassing receptacles and nonmetallic faceplates that cover the receptacle face, where the plate cannot be installed on any other receptacle , shall be permitted.
After installation, receptacle faces shall be flush with or project from faceplates of insulating material and shall project a minimum of 0.4 mm (0.015 in.) from metal faceplates.
(1) Countertop and Work Surfaces
Receptacles shall not be installed in a face-up position in or on countertop surfaces or work surfaces unless listed for countertop or work surface applications.(2) Under Sinks
Receptacles shall not be installed in a face-up position in the area below a sink.(H) Receptacles in Seating Areas and Other Similar Surfaces
In seating areas or similar surfaces, receptacles shall not be installed in a face-up position unless the receptacle is any of the following:
(A) Thickness of Metal Faceplates
Metal faceplates shall be of ferrous metal not less than 0.76 mm (0.030 in.) in thickness or of nonferrous metal not less than 1.02 mm (0.040 in.) in thickness.
(C) Faceplates of Insulating Material
Faceplates of insulating material shall be noncombustible and not less than 2.54 mm (0.10 in.) in thickness but shall be permitted to be less than 2.54 mm (0.10 in.) in thickness if formed or reinforced to provide adequate mechanical strength.
(C) Bathtub and Shower Space
Receptacles shall not be installed within or directly over a bathtub or shower stall.(B) Identification
Connectors designated for connection to the grounded circuit conductor shall be identified by a white-colored housing; connectors designated for connection to the grounding circuit conductor shall be identified by a green-colored housing.
(C) Interchangeability
Single-pole separable connectors shall be permitted to be interchangeable for ac or dc use or for different current ratings or voltages on the same premises , provided they are listed for ac/dc use and marked in a suitable manner to identify the system to which they are intended to be connected.408.1 Scope
This article covers switchboards switchgear , and panelboards . It does not apply to equipment operating at over volts, except as specifically referenced elsewhere in the Code.
(1) Location
Conductors and busbars shall be located so as to be free from physical damage and shall be held firmly in place.
(2) Same Vertical Section
Exception: Conductors shall be permitted to travel horizontally through vertical sections of switchboards and switchgear where such conductors are isolated from busbars by a barrier.
Other than the required interconnections and control wiring, only those conductors that are intended for termination in a vertical section of a switchboard or switchgear shall be located in that section.
(B) Overheating and Inductive Effects
The arrangement of busbars and conductors shall be such as to avoid overheating due to inductive effects.
408.8 Reconditioning of Equipment
Reconditioning of equipment within the scope of this article shall be limited as described in 408.8(A) and (B). The reconditioning process shall use design qualified parts verified under applicable standards and be performed in accordance with any instructions provided by the manufacturer. If equipment has been damaged by fire, products of combustion, or water, it shall be specifically evaluated by its manufacturer or a qualified testing laboratory prior to being returned to service
(C) Connections
Each section of equipment that requires rear or side access to make field connections shall be so marked by the manufacturer on the front. Section openings requiring rear or side access shall comply with 110.26 . Load terminals for field wiring shall comply with 408.18(C)(1) , (C)(2), or (C)(3) as applicable.
(1) Equipment Grounding Conductors
Load terminals for field wiring shall be so located that it is not necessary to reach across uninsulated ungrounded bus in order to make connections.
(3) Ungrounded Conductors
Load terminals for ungrounded conductors shall be so located that it is not necessary to reach across energized uninsulated bus in order to make connections. Bus on the line side of service , branch, or feeder disconnects is considered energized with respect to its associated load side circuits.
408.19 Conductor Insulation
An insulated conductor used within a switchboard or switchgear shall be listed, shall be flame retardant, and shall be rated not less than the voltage applied to it and not less than the voltage applied to other conductors or busbars with which it may come into contact.
408.30 General
All panelboards shall have a rating not less than the minimum feeder capacity required for the load calculated in accordance with Part III, IV, or V of Article 220 , as applicable.
(C) Delta Breakers
A 3-phase disconnect or overcurrent device shall not be connected to the bus of any panelboard that has less than 3-phase buses. Delta breakers shall not be installed in panelboards
(D) Back-Fed Devices
Plug-in-type overcurrent protection devices or plug-in type main lug assemblies that are backfed and used to terminate field-installed ungrounded supply conductors shall be secured in place by an additional fastener that requires other than a pull to release the device from the mounting means on the panel.
408.50 Panels
The panels of switchboards and switchgear shall be made of moisture-resistant, noncombustible material.
408.51 Busbars
Insulated or bare busbars shall be rigidly mounted.
(B) Side Wire-Bending Space
Side wire -bending space shall be in accordance with Table 312.6(A) for the largest conductor to be terminated in that space.
(C) Back Wire-Bending Space
Where a raceway or cable entry is in the wall of the enclosure opposite a removable cover, the distance from that wall to the cover shall be permitted to comply with the distance required for one wire per terminal in Table 312.6(A). The distance between the center of the rear entry and the nearest termination for the entering conductors shall not be less than the distance given in Table 312.6(B).
408.56 Minimum Spacings
Where close proximity does not cause excessive heating, parts of the same polarity at switches, enclosed fuses , and so forth shall be permitted to be placed as close together as convenience in handling will allow.
Exception: The distance shall be permitted to be less than that specified in Table 408.56 at circuit breakers and switches and in listed components installed in switchboards switchgear , and panelboards
Table 408.56 Minimum Spacings Between Bare Metal Parts
AC or DC Voltage Opposite Polarity Where Mounted on the Same Surface Opposite Polarity Where Held Free in Air Live Parts to Ground* mm in. mm in. mm in. Not over 125 volts, nominal 19.1 3/4 12.7 1/2 12.7 1/2 Not over 250 volts, nominal 31.8 11/4 19.1 3/4 12.7 1/2 Not over volts, nominal 50.8 2 25.4 1 25.4 1 *For spacing between live parts and doors of cabinets, the dimensions in 312.11(A) shall apply.The distance between uninsulated metal parts, busbars, and other uninsulated live parts shall not be less than specified in Table 408.56.
408.58 Panelboard Marking
Panelboards shall be durably marked by the manufacturer with the voltage and the current rating and the number of ac phases or dc buses for which they are designed and with the manufacturer's name or trademark in such a manner so as to be visible after installation, without disturbing the interior parts or wiring.409.20 Conductor Minimum Size and Ampacity
The size of the industrial control panel supply conductor shall have an ampacity not less than 125 percent of the full-load current rating of all heating loads plus 125 percent of the full-load current rating of the highest rated motor plus the sum of the full-load current ratings of all other connected motors and apparatus based on their duty cycle that may be in operation at the same time.
(A) Support and Arrangement
Busbars shall be protected from physical damage and be held firmly in place.
(B) Phase Arrangement
The phase arrangement on 3-phase horizontal common power and vertical buses shall be A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the industrial control panel . The B phase shall be that phase having the higher voltage to ground on 3-phase, 4- wire , delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations, and the phases shall be permanently marked.
410.1 Scope
portableThis article covers luminaires luminaires , lampholders, pendants, incandescent filament lamps, arc lamps, electric-discharge lamps, decorative lighting products, lighting accessories for temporary seasonal and holiday use, portable flexible lighting products, and the wiring and equipment forming part of such products and lighting installations.
410.2 Definition
Clothes Closet Storage Space. The volume bounded by the sides and back closet walls and planes extending from the closet floor vertically to a height of 1.8 m (6 ft) or to the highest clothes-hanging rod and parallel to the walls at a horizontal distance of 600 mm (24 in.) from the sides and back of the closet walls, respectively, and continuing vertically to the closet ceiling parallel to the walls at a horizontal distance of 300 mm (12 in.) or the width of the shelf, whichever is greater; for a closet that permits access to both sides of a hanging rod, this space includes the volume below the highest rod extending 300 mm (12 in.) on either side of the rod on a plane horizontal to the floor extending the entire length of the rod. See Figure 410.2.The volume bounded by the sides and back closet walls and planes extending from the closet floor vertically to a height of 1.8 m (6 ft) or to the highest clothes-hanging rod and parallel to the walls at a horizontal distance of 600 mm (24 in.) from the sides and back of the closet walls, respectively, and continuing vertically to the closet ceiling parallel to the walls at a horizontal distance of 300 mm (12 in.) or the width of the shelf, whichever is greater; for a closet that permits access to both sides of a hanging rod, this space includes the volume below the highest rod extending 300 mm (12 in.) on either side of the rod on a plane horizontal to the floor extending the entire length of the rod. See Figure 410.2.
FIGURE 410.2 Clothes Closet Storage Space.The definition in this section shall apply only within this article.
(B) Corrosive Locations
Luminaires installed in corrosive locations shall be of a type suitable for such locations.(C) In Ducts or Hoods
Informational Note: See 110.11 for conductors and equipment exposed to deteriorating agents.
Luminaires shall be permitted to be installed in commercial cooking hoods where all of the following conditions are met:410.11 Luminaires Near Combustible Material
Luminaires shall be constructed, installed, or equipped with shades or guards so that combustible material is not subjected to temperatures in excess of 90°C (194°F).410.12 Luminaires Over Combustible Material
Lampholders installed over highly combustible material shall be of the unswitched type. Unless an individual switch is provided for each luminaire , lampholders shall be located at least 2.5 m (8 ft) above the floor or shall be located or guarded so that the lamps cannot be readily removed or damaged.
(C) Location
The minimum clearance between luminaires installed in clothes closets and the nearest point of a clothes closet storage space shall be as follows:
410.18 Space for Cove Lighting
Coves shall have adequate space and shall be located so that lamps and equipment can be properly installed and maintained.
(B) Access to Boxes
Electric-discharge and LED luminaires surface mounted over concealed outlet , pull, or junction boxes and designed not to be supported solely by the outlet box shall be provided with suitable openings in the back of the luminaire to provide access to the wiring in the box.
(A) General
Luminaires and lampholders shall be securely supported. A luminaire that weighs more than 3 kg (6 lb) or exceeds 400 mm (16 in.) in any dimension shall not be supported by the screw shell of a lampholder.(B) Suspended Ceilings
Framing members of suspended ceiling systems used to support luminaires shall be securely fastened to each other and shall be securely attached to the building structure at appropriate intervals. Luminaires shall be securely fastened to the ceiling framing member by mechanical means such as bolts, screws, or rivets. Listed clips identified for use with the type of ceiling framing member(s) and luminaire (s) shall also be permitted.
(C) Luminaire Studs
Luminaire studs that are not a part of outlet boxes, hickeys, tripods, and crowfeet shall be made of steel, malleable iron, or other material suitable for the application.(D) Insulating Joints
Insulating joints that are not designed to be mounted with screws or bolts shall have an exterior metal casing, insulated from both screw connections.
(G) Trees
Informational Note No. 1: See 225.26 for restrictions for support of overhead conductors.
Informational Note No. 2: See 300.5(D) for protection of conductors.
Outdoor luminaires and associated equipment shall be permitted to be supported by trees.
410.48 Luminaire Wiring General
Wiring on or within luminaires shall be neatly arranged and shall not be exposed to physical damage. Excess wiring shall be avoided. Conductors shall be arranged so that they are not subjected to temperatures above those for which they are rated.
(A) Support
Pendant lampholders with permanently attached leads, where used for other than festoon wiring, shall be hung from separate stranded rubber- covered conductors that are soldered directly to the circuit conductors but supported independently thereof.
(B) Size
Unless part of listed decorative lighting assemblies, pendant conductors shall not be smaller than 14 AWG for mogul-base or medium-base screw shell lampholders or smaller than 18 AWG for intermediate or candelabra-base lampholders.
(C) Twisted or Cabled
Pendant conductors longer than 900 mm (3 ft) shall be twisted together where not cabled in a listed assembly.
(A) Properly Secured
Conductors shall be secured in a manner that does not tend to cut or abrade the insulation.
(B) Protection Through Metal
Conductor insulation shall be protected from abrasion where it passes through metal.
(C) Luminaire Stems
Splices and taps shall not be located within luminaire arms or stems.
(E) Stranding
Stranded conductors shall be used for wiring on luminaire chains and on other movable or flexible parts.
(F) Tension
Conductors shall be arranged so that the weight of the luminaire or movable parts does not put tension on the conductors.
410.59 Cord-Connected Showcases
The installation shall comply with 410.59(A) through (E).
Individual showcases, other than fixed, shall be permitted to be connected by flexible cord to permanently installed receptacles , and groups of not more than six such showcases shall be permitted to be coupled together by flexible cord and separable locking-type connectors with one of the group connected by flexible cord to a permanently installed receptacle
(C) Support
Flexible cords shall be secured to the undersides of showcases such that all of the following conditions are ensured:
(E) Secondary Circuit(s)
Where showcases are cord-connected, the secondary circuit(s) of each electric-discharge lighting ballast shall be limited to one showcase.
(A) Lampholders
3/8) pipe size. The cord hole shall be of a size appropriate for the cord, and all burrs and fins shall be removed in order to provide a smooth bearing surface for the cord.Bushing having holes 7 mm (9/32 in.) in diameter shall be permitted for use with plain pendant cord and holes 11 mm (13/32 in.) in diameter with reinforced cord.
Where a metal lampholder is attached to a flexible cord, the inlet shall be equipped with an insulating bushing that, if threaded, is not smaller than metric designator 12 (trade size) pipe size. The cord hole shall be of a size appropriate for the cord, and all burrs and fins shall be removed in order to provide a smooth bearing surface for the cord.
(1) Cord-Connected Installation
(a) A luminaire shall be permitted to be connected with a cord terminating in a grounding -type attachment plug or busway plug. If grounding is not required in accordance with 410.42 , a polarized-type plug shall be permitted.
(b) A luminaire assembly equipped with a strain relief and canopy shall be permitted to use a cord connection between the luminaire assembly and the canopy. The canopy shall be permitted to include a section of raceway not over 150 mm ( 6 in.) in length and intended to facilitate the connection to an outlet box mounted above a suspended ceiling.
(c) Listed luminaires connected using listed assemblies that incorporate manufactured wiring system connectors in accordance with 604.100(C) shall be permitted to be cord connected.
luminaire or a listed assembly in compliance with any of the conditions in 410.62(C)(1)(a) through (C)(1)(c) shall be permitted to be cord connected provided the luminaire is located directly below the outlet or busway, the cord is not subject to strain or physical damage, and the cord is visible over its entire length except at terminations.410.70 Combustible Shades and Enclosures
Air space shall be provided between lamps and shades or other enclosures of combustible material.
(A) Marking
All luminaires shall be marked with the maximum lamp wattage or electrical rating, manufacturer's name, trademark, or other suitable means of identification. A luminaire requiring supply wire rated higher than 60°C (140°F) shall be marked with the minimum supply wire temperature rating on the luminaire and shipping carton or equivalent.
(B) Electrical Rating
The electrical rating shall include the voltage and frequency and shall indicate the current rating of the unit, including the ballast, transformer, LED driver, power supply, or autotransformer.
410.84 Cord Bushings
A bushing or the equivalent shall be provided where flexible cord enters the base or stem of a portable luminaire . The bushing shall be of insulating material unless a jacketed type of cord is used.
410.90 Screw Shell Type
Lampholders of the screw shell type shall be installed for use as lampholders only. Where supplied by a circuit having a grounded conductor , the grounded conductor shall be connected to the screw shell.
410.93 Double-Pole Switched Lampholders
Where supplied by the ungrounded conductors of a circuit, the switching device of lampholders of the switched type shall simultaneously disconnect both conductors of the circuit.
410.97 Lampholders Near Combustible Material
Lampholders shall be constructed, installed, or equipped with shades or guards so that combustible material is not subjected to temperatures in excess of 90°C (194°F).
410.103 Bases, Incandescent Lamps
An incandescent lamp for general use on lighting branch circuits shall not be equipped with a medium base if rated over 300 watts, or with a mogul base if rated over watts. Special bases or other devices shall be used for over watts.
(A) Enclosures
Auxiliary equipment for electric-discharge lamps shall be enclosed in noncombustible cases and treated as sources of heat.
(A) Combustible Material
Luminaires shall be installed so that adjacent combustible material will not be subjected to temperatures in excess of 90°C (194°F).(1) Non-Type IC
2 in.) from combustible materials. The points of support and the trim finishing off the openings in the ceiling, wall, or other finished surface shall be permitted to be in contact with combustible materials.A recessed luminaire that is not identified for contact with insulation shall have all recessed parts spaced not less than 13 mm ( 1 in.) from combustible materials. The points of support and the trim finishing off the openings in the ceiling, wall, or other finished surface shall be permitted to be in contact with combustible materials.
(2) Type IC
A recessed luminaire that is identified for contact with insulation, Type IC, shall be permitted to be in contact with combustible materials at recessed parts, points of support, and portions passing through or finishing off the opening in the building structure.
(B) Installation
Thermal insulation shall not be installed above a recessed luminaire or within 75 mm (3 in.) of the recessed luminaire 's enclosure , wiring compartment, ballast, transformer, LED driver, or power supply unless the luminaire is identified as Type IC for insulation contact.
(C) Installation in Fire-Resistant Construction
(A) General
Conductors that have insulation suitable for the temperature encountered shall be used.
(C) Tap Conductors
Tap conductors of a type suitable for the temperature encountered shall be permitted to run from the luminaire terminal connection to an outlet box placed at least 300 mm (1 ft) from the luminaire . Such tap conductors shall be in suitable raceway or Type AC or MC cable of at least 450 mm (18 in.) but not more than 1.8 m (6 ft) in length.
410.119 Temperature
Luminaires shall be constructed such that adjacent combustible material is not subject to temperatures in excess of 90°C (194°F).410.120 Lamp Wattage Marking
1/4 in.) high, and shall be located where visible during relamping.Incandescent lamp luminaires shall be marked to indicate the maximum allowable wattage of lamps. The markings shall be permanently installed, in letters at least 6 mm (in.) high, and shall be located where visible during relamping.
410.121 Solder Prohibited
No solder shall be used in the construction of a luminaire recessed housing.
410.122 Lampholders
Lampholders of the screw shell type shall be of porcelain or other suitable insulating materials.
(C) Transformers of the Oil-Filled Type
Transformers of the oil-filled type shall not be used.
(D) Additional Requirements
In addition to complying with the general requirements for luminaires , such equipment shall comply with Part XII of this article.
(1) Integral Thermal Protection
The ballast of a fluorescent luminaire installed indoors shall have integral thermal protection. Replacement ballasts shall also have thermal protection integral with the ballast.
(3) Exit Luminaires
A ballast in a fluorescent exit luminaire shall not have thermal protection.
(4) Egress Luminaires
A ballast in a fluorescent luminaire that is used for egress lighting and energized only during a failure of the normal supply shall not have thermal protection.
(1) Recessed
Recessed high-intensity luminaires designed to be installed in wall or ceiling cavities shall have thermal protection and be identified as thermally protected
(5) Metal Halide Lamp Containment
Informational Note: See ANSI Standard C78.389, American National Standard for Electric Lamps High Intensity Discharge, Methods of Measuring Characteristics.
Luminaires that use a metal halide lamp other than a thick-glass parabolic reflector lamp (PAR) shall be provided with a containment barrier that encloses the lamp, or shall be provided with a physical means that only allows the use of a lamp that is Type O.(A) Exposed Components
Luminaires that have exposed ballasts, transformers, LED drivers, or power supplies shall be installed such that ballasts, transformers, LED drivers, or power supplies shall not be in contact with combustible material unless listed for such condition.(B) Combustible Low-Density Cellulose Fiberboard
1/2 in.) from the surface of the fiberboard. Where such 3 (20 lb/ft3) or less and that are formed of 3 (20 lb/ft3) or is a material that has been integrally treated with fire-retarding chemicals to the degree that the flame spread index in any plane of the material will not exceed 25, determined in accordance with tests for surface burning characteristics of building materials. See ASTM E84-18a, Standard Test Method for Surface Burning Characteristics of Building Materials, or ANSI/UL 723-, Standard for Test for Surface Burning Characteristics of Building Materials.Informational Note: Combustible low-density cellulose fiberboard includes sheets, panels, and tiles that have a density of 320 kg/m(20 lb/ft) or less and that are formed of bonded plant fiber material but does not include solid or laminated wood or fiberboard that has a density in excess of 320 kg/m(20 lb/ft) or is a material that has been integrally treated with fire-retarding chemicals to the degree that the flame spread index in any plane of the material will not exceed 25, determined in accordance with tests for surface burning characteristics of building materials. See ASTM E84-18a, Standard Test Method for Surface Burning Characteristics of Building Materials, or ANSI/UL 723-, Standard for Test for Surface Burning Characteristics of Building Materials.
Where a surface-mounted luminaire containing a ballast, transformer, LED driver, or power supply is to be installed on combustible low-density cellulose fiberboard, it shall be marked for this condition or shall be spaced not less than 38 mm (1in.) from the surface of the fiberboard. Where such luminaires are partially or wholly recessed, the provisions of 410.110 through 410.122 shall apply.
(B) Separate Mounting
Separately mounted ballasts, transformers, LED drivers, or power supplies that are listed for direct connection to a wiring system shall not be required to be additionally enclosed
410.138 Autotransformers
An autotransformer that is used to raise the voltage to more than 300 volts, as part of a ballast for supplying lighting units, shall be supplied only by a grounded system.
(C) Live Parts
The terminal of an electric-discharge lamp shall be considered as a live part.
410.142 Lamp Terminals and Lampholders
Parts that must be removed for lamp replacement shall be hinged or held captive. Lamps or lampholders shall be designed so that there are no exposed live parts when lamps are being inserted or removed.
(B) Voltage
The secondary circuit voltage shall not exceed 15,000 volts, nominal, under any load condition. The voltage to ground of any output terminals of the secondary circuit shall not exceed volts under any load conditions.
(C) Rating
Transformers shall have a secondary short-circuit current rating of not more than 150 mA if the open-circuit voltage is over volts, and not more than 300 mA if the open-circuit voltage rating is volts or less.
(D) Secondary Connections
Secondary circuit outputs shall not be connected in parallel or in series.
(B) Secondary Conductors
Transformers shall be installed as near to the lamps as practicable to keep the secondary conductors as short as possible.
(C) Adjacent to Combustible Materials
Transformers shall be located so that adjacent combustible materials are not subjected to temperatures in excess of 90°C (194°F).
410.145 Exposure to Damage
Lamps shall not be located where normally exposed to physical damage.
410.146 Marking
1/4 in.) high reading "Caution ____ volts." TheEach luminaire or each secondary circuit of tubing having an open-circuit voltage of over volts shall have a clearly legible marking in letters not less than 6 mm (in.) high reading "Caution ____ volts." The voltage indicated shall be the rated open-circuit voltage . The caution sign(s) or label(s) shall comply with 110.21(B)
(C) Locations Not Permitted
410.154 Fastening
Lighting track shall be securely mounted so that each fastening is suitable for supporting the maximum weight of luminaires that can be installed. Unless identified for supports at greater intervals, a single section 1.2 m (4 ft) or shorter in length shall have two supports, and, where installed in a continuous row, each individual section of not more than 1.2 m (4 ft) in length shall have one additional support.(A) Construction
The housing for the lighting track system shall be of substantial construction to maintain rigidity. The conductors shall be installed within the track housing, permitting insertion of a luminaire , and designed to prevent tampering and accidental contact with live parts . Components of lighting track systems of different voltages shall not be interchangeable. The track conductors shall be a minimum 12 AWG or equal and shall be copper. The track system ends shall be insulated and capped.
410.160 Listing of Decorative Lighting
Decorative lighting and similar accessories used for holiday lighting and similar purposes, in accordance with 590.3(B) , shall be listed.
410.170 General
Informational Note: Lighting equipment identified for horticultural use is designed to provide a spectral characteristic needed for the growth of plants and can also provide supplemental general illumination within the growing environment.
Luminaires complying with Parts, I, II, III, IV, V, VI, VII, IX, X, XI, and XII of this article shall be permitted to be used for horticultural lighting. Part XVI shall additionally apply to lighting equipment specifically identified for horticultural use.410.174 Installation and Use
Lighting equipment identified for horticultural use shall be installed and used in accordance with the manufacturer's installation instructions and installation markings on the equipment as required by that listing.
(A) General Lighting
Lighting equipment identified for horticultural use shall not be installed as lighting for general illumination unless such use is indicated in the manufacturer's instructions.
(B) Installed Location
Lighting equipment identified for horticultural use shall not be installed where it is likely to be subject to physical damage or where concealed
410.178 Flexible Cord
Informational Note: Remote power sources include LED drivers, fluorescent ballasts, or HID ballasts.
Flexible cord shall only be permitted when provided as part of listed lighting equipment identified for horticultural use for any of the following uses:
410.186 Support
Special fittings identified for support of horticultural lighting equipment shall be designed specifically for the horticultural lighting equipment on which they are installed and shall be used in accordance with the installation instructions provided and shall be securely fastened.
411.1 Scope
Informational Note: Refer to Article 680 for applications involving immersion.
This article covers lighting systems and their associated components operating at no more than 30 volts ac or 60 volts dc. Where wet contact is likely to occur, the limits are 15 volts ac or 30 volts dc.
(A) Walls, Floors, and Ceilings
Conductors concealed or extended through a wall, floor, or ceiling shall be in accordance with (1) or (2):
(B) Pools, Spas, Fountains, and Similar Locations
Lighting systems shall be installed not less than 3 m (10 ft) horizontally from the nearest edge of the water, unless permitted by Article 680
(A) Grounding
Secondary circuits shall not be grounded
(B) Isolation
The secondary circuit shall be insulated from the branch circuit by an isolating transformer.
411.7 Branch Circuit
Lighting systems covered by this article shall be supplied from a maximum 20-ampere branch circuit
422.1 Scope
This article covers electrical appliances used in any occupancy.
(A) General
AppliancesInformational Note: Section 210.8 specifies requirements for GFCI protection for the branch-circuit outlet where the covered location warrants such protection.
identified in 422.5(A)(1) through (A)(7) rated 150 volts or less to ground and 60 amperes or less, single-or 3-phase, shall be provided with Class A GFCI protection for personnel. Multiple Class A GFCI protective devices shall be permitted but shall not be required.422.6 Listing Required
All appliances supplied by 50 volts or higher shall be listed.
(E) Single NonMotor-Operated Appliance
If the branch circuit supplies a single nonmotor-operated appliance , the rating of overcurrent protection shall comply with the following:
(2) Commercial Kitchen and Cooking Appliances
Commercial kitchen and cooking appliances using sheathed-type heating elements not covered in 422.11(D) shall be permitted to be subdivided into circuits not exceeding 120 amperes and protected at not more than 150 amperes where one of the following is met:
(3) Water Heaters and Steam Boilers
Informational Note: Low-pressure and open- outlet heaters are atmospheric pressure water heaters as defined in IEC -2-21, Household and similar electrical appliances Safety Particular requirements for storage water heaters.
Resistance-type immersion electric heating elements shall be permitted to be subdivided into circuits not exceeding 120 amperes and protected at not more than 150 amperes as follows:
(A)
Listed central vacuum outlet assemblies shall be permitted to be connected to a branch circuit in accordance with 210.23(A)
(B)
The ampacity of the connecting conductors shall not be less than the ampacity of the branch circuit conductors to which they are connected.
(A) General
Flexible cord shall be permitted as follows:
422.19 Space for Conductors
The combined volume of the canopy of ceiling-suspended (paddle) fans and outlet box shall provide sufficient space so that conductors and their connecting devices are capable of being installed in accordance with 314.16
422.20 Outlet Boxes to Be Covered
In a completed installation, each outlet box shall be provided with a cover unless covered by means of a ceiling-suspended (paddle) fan canopy.
422.21 Covering of Combustible Material at Outlet Boxes
2 (180 in.2) or more shall be covered with noncombustible material.Any combustible ceiling finish that is exposed between the edge of a ceiling-suspended (paddle) fan canopy or pan and an outlet box and that has a surface area of mm(180 in.) or more shall be covered with noncombustible material.
(C) Rating
Exception: Demand factors authorized elsewhere in this Code shall be permitted to be applied to the rating of a receptacle or of a separable connector.
The rating of a receptacle or of a separable connector shall not be less than the rating of any appliance connected thereto.
422.41 Cord-and-Plug-Connected Appliances Subject to Immersion
Cord-and-plug-connected portable , freestanding hydromassage units and hand-held hair dryers shall be constructed to provide protection for personnel against electrocution when immersed while in the "on" or "off" position.
(A) Heater Cords
All cord-and-plug-connected smoothing irons and electrically heated appliances that are rated at more than 50 watts and produce temperatures in excess of 121°C (250°F) on surfaces with which the cord is likely to be in contact shall be provided with one of the types of approved heater cords listed in Table 400.4
422.44 Cord-and-Plug-Connected Immersion Heaters
Electric heaters of the cord-and-plug-connected immersion type shall be constructed and installed so that current-carrying parts are effectively insulated from electrical contact with the substance in which they are immersed.
422.46 Flatirons
Electrically heated smoothing irons shall be equipped with an identified temperature-limiting means.
422.47 Water Heater Controls
Exception No. 1: Storage water heaters that are identified as being suitable for use with a supply water temperature of 82°C (180°F) or above and a capacity of 60 kW or above.
Exception No. 2: Instantaneous-type water heaters that are identified as being suitable for such use, with a capacity of 4 L (1 gal) or less.
Informational Note: See ANSI Z21.22-/CSA 4.4-M99, Relief Valves for Hot Water Supply Systems.
All storage or instantaneous-type water heaters shall be equipped with a temperature-limiting means in addition to its control thermostat to disconnect all ungrounded conductors. Such means shall comply with both of the following:
(A) 300 Watts or Less
Infrared heating lamps rated at 300 watts or less shall be permitted with lampholders of the medium-base, unswitched porcelain type or other types identified as suitable for use with infrared heating lamps rated 300 watts or less.
(B) Over 300 Watts
Screw shell lampholders shall not be used with infrared lamps rated over 300 watts, unless the lampholders are identified as being suitable for use with infrared heating lamps rated over 300 watts.
422.50 Cord-and-Plug-Connected Pipe Heating Assemblies
Cord-and-plug-connected pipe heating assemblies intended to prevent freezing of piping shall be listed.
(A) Nameplate Marking
Where motor overload protection external to the appliance is required, the appliance shall be so marked.
Informational Note: See 422.11 for overcurrent protection requirements.
Each electrical appliance shall be provided with a nameplate giving the identifying name and the rating in volts and amperes, or in volts and watts. If the appliance is to be used on a specific frequency or frequencies, it shall be so marked.
(B) To Be Visible
Marking shall be located so as to be visible or easily accessible after installation.
422.61 Marking of Heating Elements
All heating elements that are rated over one ampere, replaceable in the field, and a part of an appliance shall be legibly marked with the ratings in volts and amperes, or in volts and watts, or with the manufacturer's part number.
(A) Nameplate Horsepower Markings
Where a motor-operated appliance nameplate includes a horsepower rating, that rating shall not be less than the horsepower rating on the motor nameplate. Where an appliance consists of multiple motors, or one or more motors and other loads, the nameplate value shall not be less than the equivalent horsepower of the combined loads, calculated in accordance with 430.110(C)(1)
(1) Marking
In addition to the marking required in 422.60 , the marking on an appliance consisting of a motor with other load(s) or motors with or without other load(s) shall specify the minimum supply circuit conductor ampacity and the maximum rating of the circuit overcurrent protective device . This requirement shall not apply to an appliance with a nameplate in compliance with 422.60 where both the minimum supply circuit conductor ampacity and maximum rating of the circuit overcurrent protective device are not more than 15 amperes.
(2) Alternate Marking Method
1/8 horsepower or less or a nonmotor load 1 ampere or less shall be permitted to be omitted unless such loads constitute the principal load.An alternate marking method shall be permitted to specify the rating of the largest motor in volts and amperes, and the additional load(s) in volts and amperes, or volts and watts in addition to the marking required in 422.60 . The ampere rating of a motorhorsepower or less or a nonmotor load 1 ampere or less shall be permitted to be omitted unless such loads constitute the principal load.
424.2 Definitions
Heating Panel. A complete assembly provided with a junction box or a length of flexible conduit for connection to aA complete assembly provided with a junction box or a length of flexible conduit for connection to a branch circuit
Heating Panel Set. A rigid or nonrigid assembly provided with nonheating leads or aA rigid or nonrigid assembly provided with nonheating leads or a terminal junction assembly identified as being suitable for connection to a wiring system.
The definitions in this section shall apply only within this article.
(B) Branch-Circuit Sizing
The branch-circuit conductors for fixed electric space- heating equipment and any associated motors shall be sized not smaller than 125 percent of the load.
424.11 Supply Conductors
Fixed electric space- heating equipment requiring supply conductors with an insulation rating greater than 60°C shall be clearly and permanently marked. This marking shall be plainly visible after installation and shall be permitted to be adjacent to the field connection box.
424.13 Spacing From Combustible Materials
Fixed electric space- heating equipment shall be installed to provide the required spacing between the equipment and adjacent combustible material, unless it is listed to be installed in direct contact with combustible material.
(A) Marking Required
1/8 hp and other loads shall specify the rating of the motor in volts, amperes, and frequency, and the heating load in volts and watts or in volts and amperes.Electric space- heating equipment intended for use on alternating current only, direct current only, or both shall be marked to so indicate. The marking of equipment consisting of motors overhp and other loads shall specify the rating of the motor in volts, amperes, and frequency, and the heating load in volts and watts or in volts and amperes.
Each unit of fixed electric space- heating equipment shall be provided with a nameplate giving the identifying name and the normal rating in volts and watts or in volts and amperes.
(B) Location
This nameplate shall be located so as to be visible or accessible after installation.
424.29 Marking of Heating Elements
All heating elements that are replaceable in the field and are part of an electric heater shall be legibly marked with the ratings in volts and watts or in volts and amperes.
424.34 Heating Cable Construction
Factory-assembled nonheating leads of heating cables , if any, shall be at least 2.1 m (7 ft) in length.
424.35 Marking of Heating Cables
Each unit shall be marked with the identifying name or identification symbol, catalog number, and ratings in volts and watts or in volts and amperes.
424.36 Clearances of Wiring in Ceilings
Wiring located above heated ceilings shall be spaced not less than 50 mm (2 in.) above the heated ceiling. The ampacity of conductors shall be calculated on the basis of an assumed ambient temperature of not less than 50°C (122°F), applying the correction factors in accordance with 310.15(B)(1) . If this wiring is located above thermal insulation having a minimum thickness of 50 mm (2 in.), it shall be subject to the ambient correction in accordance with 310.15(B)(1)
(B) Uses Not Permitted
Heating cables shall not be installed as follows:
424.40 Splices
The length of heating cable shall only be altered using splices identified in the manufacturer's instructions.
(A) In Walls
Cables shall not be installed in walls unless it is necessary for an isolated single run of cable to be installed down a vertical surface to reach a dropped ceiling.(B) Adjacent Runs
Adjacent runs of heating cable shall be installed in accordance with the manufacturer's instructions.
(C) Surfaces to Be Applied
Informational Note: See also 424.41(F)
Heating cables shall be applied only to gypsum board, plaster lath, or other fire-resistant material. With metal lath or other electrically conductive surfaces, a coat of plaster or other means employed in accordance with the heating cable manufacturer's instructions shall be applied to completely separate the metal lath or conductive surface from the cable
(D) Splices
All heating cables , the splice between the heating cable and nonheating leads, and 75-mm (3-in.) minimum of the nonheating lead at the splice shall be embedded in plaster or dry board in the same manner as the heating cable
(E) Ceiling Surface
1/2 in.), or other noninsulating materialThe entire ceiling surface shall have a finish of thermally noninsulating sand plaster that has a nominal thickness of 13 mm (in.), or other noninsulating material identified as suitable for this use and applied according to specified thickness and directions.
(F) Secured
Cables shall be secured by means of approved stapling, tape, plaster, nonmetallic spreaders, or other approved means either at intervals not exceeding 400 mm (16 in.) or at intervals not exceeding 1.8 m (6 ft) for cables identified for such use. Staples or metal fasteners that straddle the cable shall not be used with metal lath or other electrically conductive surfaces.(G) Dry Board Installations
1/2 in.) thickness. The void between the upper layer of gypsum board, plaster lath, or other fire-resistant material and the surface layer of gypsum board shall be completely filled with thermally conductive, nonshrinking plaster or otherIn dry board installations, the entire ceiling below the heating cable shall be covered with gypsum board not exceeding 13 mm (in.) thickness. The void between the upper layer of gypsum board, plaster lath, or other fire-resistant material and the surface layer of gypsum board shall be completely filled with thermally conductive, nonshrinking plaster or other approved material or equivalent thermal conductivity.
(I) Joists
1/2 in.) (width) between centers of adjacent runs ofIn dry board applications, cable shall be installed parallel to the joist, leaving a clear space centered under the joist of 65 mm (2in.) (width) between centers of adjacent runs of cable . A surface layer of gypsum board shall be mounted so that the nails or other fasteners do not pierce the heating cable
(J) Crossing Joists
Cables shall cross joists only at the ends of the room unless the cable is required to cross joists elsewhere in order to satisfy the manufacturer's instructions regarding clearance from ceiling penetrations and luminaires424.42 Finished Ceilings
Finished ceilings shall not be covered with decorative panels or beams constructed of materials that have thermal insulating properties, such as wood, fiber, or plastic. Finished ceilings shall be permitted to be covered with paint, wallpaper, or other approved surface finishes.
(A) Free Nonheating Leads
Free nonheating leads of cables shall be installed in accordance with Chapter 3 wiring methods, or other listed means, from the junction box to a location within the ceiling.
(B) Leads in Junction Box
Not less than 150 mm (6 in.) of free nonheating lead shall be within the junction box. The marking of the leads shall be visible in the junction box.
(C) Excess Leads
Excess leads of heating cables shall not be cut but shall be secured to the underside of the ceiling and embedded in plaster or other approved material, leaving only a length sufficient to reach the junction box with not less than 150 mm (6 in.) of free lead within the box.
(A) Adjacent Runs
Adjacent runs of heating cable shall be installed in accordance with the manufacturer's instructions.
(C) Leads Protected
Leads shall be protected where they leave the floor by rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, electrical metallic tubing, or by other approved means.
(A) Identification
Heating cables for installation under floor covering shall be identified as suitable for installation under floor covering.
(B) Expansion Joints
Heating cables shall not be installed where they bridge expansion joints unless provided with expansion and contraction fittings applicable to the manufacture of the cable
(D) Anchoring
Heating cables shall be positioned and secured in place under the floor covering, in accordance with the manufacturer's instructions.
424.57 General
Part VI shall apply to any heater mounted in the airstream of a forced-air system where the air-moving unit is not provided as an integral part of the equipment
424.58 Identification
Heaters installed in an air duct shall be identified as suitable for the installation.
424.59 Airflow
Informational Note: Heaters installed within 1.2 m (4 ft) of the outlet of an air-moving device , heat pump, air conditioner, elbows, baffle plates, or other obstructions in ductwork may require turning vanes, pressure plates, or other devices on the inlet side of the duct heater to ensure an even distribution of air over the face of the heater.
Means shall be provided to ensure uniform airflow over the face of the heater in accordance with the manufacturer's instructions.
424.60 Elevated Inlet Temperature
Duct heaters intended for use with elevated inlet air temperature shall be identified as suitable for use at the elevated temperatures.
424.61 Installation of Duct Heaters With Heat Pumps and Air Conditioners
Heat pumps and air conditioners having duct heaters closer than 1.2 m (4 ft) to the heat pump or air conditioner shall have both the duct heater and heat pump or air conditioner identified as suitable for such installation and so marked.
424.62 Condensation
Duct heaters used with air conditioners or other air-cooling equipment that could result in condensation of moisture shall be identified as suitable for use with air conditioners.
424.63 Fan Circuit Interlock
Means shall be provided to ensure that the fan circuit is energized when any heater circuit is energized . However, time-or temperature-controlled delay in energizing the fan motor shall be permitted.
424.64 Limit Controls
In addition, an integral independent supplementary control or controllers shall be provided in each duct heater that disconnects a sufficient number of conductors to interrupt current flow. This device shall be manually resettable or replaceable.
Each duct heater shall be provided with an approved , integral, automatic -reset temperature-limiting control or controllers to de-energize the circuit or circuits.
424.66 Installation
Informational Note: For additional installation information, see NFPA 90A-, Standard for the Installation of Air-Conditioning and Ventilating Systems, and NFPA 90B-, Standard for the Installation of Warm Air Heating and Air-Conditioning Systems.
Duct heaters shall be installed in accordance with the manufacturer's instructions in such a manner that the operation of the duct heater does not create a hazard to persons or property. Furthermore, duct heaters shall be located with respect to building construction and other equipment so as to permit access to the heater and the heater control . Sufficient clearance shall be maintained to permit replacement of controls and heating elements and for adjusting and cleaning of controls and other parts requiring such attention. See 110.26.
424.70 Scope
The provisions in Part VII of this article shall apply to boilers employing resistance-type heating elements. See Part VIII of this article for electrode-type boilers.
424.71 Identification
Resistance-type boilers shall be identified as suitable for the installation.
424.73 Overtemperature Limit Control
Each boiler designed so that in normal operation there is no change in state of the heat transfer medium shall be equipped with a temperature-sensitive limiting means. It shall be installed to limit maximum liquid temperature and shall directly or indirectly disconnect all ungrounded conductors to the heating elements. Such means shall be in addition to a temperature-regulating system and other devices protecting the tank against excessive pressure.
424.74 Overpressure Limit Control
Each boiler designed so that in normal operation there is a change in state of the heat transfer medium from liquid to vapor shall be equipped with a pressure-sensitive limiting means. It shall be installed to limit maximum pressure and shall directly or indirectly disconnect all ungrounded conductors to the heating elements. Such means shall be in addition to a pressure-regulating system and other devices protecting the tank against excessive pressure.
424.80 Scope
Informational Note: For over 600 volts, see Part V of Article 490
The provisions in Part VIII of this article shall apply to boilers for operation at 600 volts, nominal, or less, in which heat is generated by the passage of current between electrodes through the liquid being heated.
424.81 Identification
Electrode-type boilers shall be identified as suitable for the installation.
424.82 Branch-Circuit Requirements
Where an electrode boiler is rated 50 kW or more, the conductors supplying the boiler electrode(s) shall be permitted to be sized at not less than 100 percent of the nameplate rating of the electrode boiler, provided all the following conditions are met:
The size of branch-circuit conductors and overcurrent protective devices shall be calculated on the basis of 125 percent of the total load (motors not included). A contactor, relay, or other device approved for continuous operation at 100 percent of its rating, shall be permitted to supply its full-rated load. See 210.19(A) , Exception. The provisions of this section shall not apply to conductors that form an integral part of an approved boiler.
424.83 Overtemperature Limit Control
Each boiler, designed so that in normal operation there is no change in state of the heat transfer medium, shall be equipped with a temperature-sensitive limiting means. It shall be installed to limit maximum liquid temperature and shall directly or indirectly interrupt all current flow through the electrodes. Such means shall be in addition to the temperature-regulating system and other devices protecting the tank against excessive pressure.
424.84 Overpressure Limit Control
Each boiler, designed so that in normal operation there is a change in state of the heat transfer medium from liquid to vapor, shall be equipped with a pressure-sensitive limiting means. It shall be installed to limit maximum pressure and shall directly or indirectly interrupt all current flow through the electrodes. Such means shall be in addition to a pressure-regulating system and other devices protecting the tank against excessive pressure.
424.86 Markings
A field-applied warning marking or label shall comply with 110.21(B) . The nameplate shall be located so as to be visible after installation.
All electrode-type boilers shall be marked to show the following:
(A) Location
Markings shall be permanent and in a location that is visible prior to application of panel finish.
(C) Required Markings
Each unit shall be marked with the identifying name or identification symbol, catalog number, and rating in volts and watts or in volts and amperes.
(2) Locations Not Permitted
The heating portion shall not be installed as follows:
(5) Surface Coverings
Surfaces permitted by 424.93(A)(4) shall be permitted to be covered with paint, wallpaper, or other approved surfaces identified in the manufacturer's instructions as being suitable.
(1) Mounting Location
Heating panel sets shall be permitted to be secured to the lower face of joists or mounted in between joists, headers, or nailing strips.(3) Installation of Nails, Staples, or Other Fasteners
1/4 in.) to the element. Nails, staples, or other fasteners shall not be used where they penetrate current-carrying parts.Nailing or stapling of heating panel sets shall be done only through the unheated portions provided for this purpose. Heating panel sets shall not be cut through or nailed through any point closer than 6 mm (in.) to the element. Nails, staples, or other fasteners shall not be used where they penetrate current-carrying parts.
424.94 Clearances of Wiring in Ceilings
Wiring located above heated ceilings shall be spaced not less than 50 mm (2 in.) above the heated ceiling. The ampacity shall be calculated on the basis of an assumed ambient temperature of not less than 50°C (122°F), applying the correction factors in accordance with 310.15(B)(1) . If this wiring is located above thermal insulation having a minimum thickness of 50 mm (2 in.), it shall be subject to the ambient correction in accordance with 310.15(B)(1)
(D) Protection of Leads
Leads shall be protected where they leave the floor by rigid metal conduit, intermediate metal conduit, rigid nonmetallic conduit, or electrical metallic tubing, or by other approved means.
(B) Installation
Listed heating panels or panel sets, if installed under floor covering, shall be installed on surfaces that are smooth and flat in accordance with the manufacturer's instructions and shall also comply with 424.99(B)(1) through (B)(6).
(A) Power Unit
The power unit shall be an isolating type with a rated output not exceeding 25 amperes, 30 volts (42.4 volts peak) ac, or 60 volts dc under all load conditions.
(B) Ground
Secondary circuits shall not be grounded
425.11 Supply Conductors
Fixed industrial process heating equipment requiring supply conductors with over 60°C insulation shall be clearly and permanently marked. This marking shall be plainly visible after installation and shall be permitted to be adjacent to the field connection box.
425.13 Spacing From Combustible Materials
Fixed industrial process heating equipment shall be installed to provide the required spacing between the equipment and adjacent combustible material, unless it is listed to be installed in direct contact with combustible material.
(A) Marking Required
1/8 hp and other loads shall specify the rating of the motor in volts, amperes, and frequency and the heating load in volts and watts or in volts and amperes.Fixed industrial process heating equipment intended for use on alternating current only, direct current only, or both shall be marked to so indicate. The marking of equipment consisting of motors overhp and other loads shall specify the rating of the motor in volts, amperes, and frequency and the heating load in volts and watts or in volts and amperes.
Fixed industrial process heating equipment shall be provided with a nameplate identifying the manufacturer and the rating in volts and watts or in volts and amperes.
(B) Location
This nameplate shall be located so as to be permanent and shall be visible or accessible after installation.
425.29 Marking of Heating Elements
All heating elements that are replaceable in the field and are part of industrial process heating equipment shall be legibly marked with the ratings in volts and watts or in volts and amperes.
425.57 General
Part V shall apply to any heater mounted in the airstream of a forced-air system where the air-moving unit is not provided as an integral part of the equipment
425.58 Identification
Heaters installed in an air duct shall be identified as suitable for the installation.
425.59 Airflow
Informational Note: Some heaters installed within 1.2 m (4 ft) of the outlet of an air-moving device , elbows, baffle plates, or other obstructions in ductwork use turning vanes, pressure plates, or other devices on the inlet side of the duct heater to ensure an even distribution of air over the face of the heater.
Means shall be provided to ensure uniform airflow over the face of the heater in accordance with the manufacturer's instructions.
425.60 Elevated Inlet Temperature
Duct heaters intended for use with elevated inlet air temperature shall be identified as suitable for use at the elevated temperatures.
425.63 Fan Circuit Interlock
Means shall be provided to ensure that the fan circuit, where present, is energized when any heater circuit is energized . However, time-or temperature-controlled delay in energizing the fan motor shall be permitted.
425.64 Limit Controls
Each duct heater shall be provided with an integral, automatic -reset temperature-limiting control or controllers to de-energize the circuit or circuits. In addition, an integral independent supplementary control or controllers shall be provided in each duct heater that disconnects a sufficient number of conductors to interrupt heating element current flow. This device shall be manually resettable or replaceable.
425.70 Scope
The provisions in Part VI of this article shall apply to boilers employing resistance-type heating elements. Electrode-type boilers shall not be considered as employing resistance-type heating elements. See Part VII of this article.
425.71 Identification
Resistance-type boilers shall be identified as suitable for the installation.
425.73 Overtemperature Limit Control
Each boiler designed so that in normal operation there is no change in state of the heat transfer medium shall be equipped with a temperature-sensitive limiting means. It shall be installed to limit maximum liquid temperature and shall directly or indirectly disconnect all ungrounded conductors to the heating elements. Such means shall be in addition to a temperature-regulating system and other devices protecting the tank against excessive pressure.
425.74 Overpressure Limit Control
Each boiler designed so that in normal operation there is a change in state of the heat transfer medium from liquid to vapor shall be equipped with a pressure-sensitive limiting means. It shall be installed to limit maximum pressure and shall directly or indirectly disconnect all ungrounded conductors to the heating elements. Such means shall be in addition to a pressure-regulating system and other devices protecting the tank against excessive pressure.
425.80 Scope
The provisions in Part VII of this article shall apply to boilers for operation at 600 volts, nominal, or less, in which heat is generated by the passage of current between electrodes through the liquid being heated.
425.81 Identification
Electrode-type boilers shall be identified as suitable for the installation.
425.82 Branch-Circuit Requirements
Where an electrode boiler is rated 50 kW or more, the conductors supplying the boiler electrode(s) shall be permitted to be sized at not less than 100 percent of the nameplate rating of the electrode boiler, provided all the following conditions are met:
The size of branch-circuit conductors and overcurrent protective devices shall be calculated on the basis of 125 percent of the total load (motors not included). A contactor, relay, or other device , listed for continuous operation at 100 percent of its rating, shall be permitted to supply its full-rated load. See 210.19(A)(1) (a), Exception No. 1. This section shall not apply to conductors that form an integral part of an approved boiler.
425.83 Overtemperature Limit Control
Each boiler, designed so that in normal operation there is no change in state of the heat transfer medium, shall be equipped with a temperature-sensitive limiting means. It shall be installed to limit maximum liquid temperature and shall directly or indirectly interrupt all current flow through the electrodes. Such means shall be in addition to the temperature regulating system and other devices protecting the tank against excessive pressure.
425.84 Overpressure Limit Control
Each boiler, designed so that in normal operation there is a change in state of the heat transfer medium from liquid to vapor, shall be equipped with a pressure-sensitive limiting means. It shall be installed to limit maximum pressure and shall directly or indirectly interrupt all current flow through the electrodes. Such means shall be in addition to a pressure-regulating system and other devices protecting the tank against excessive pressure.
425.86 Markings
A field-applied warning marking or label shall comply with 110.21(B) . The markings shall be permanent and located so as to be visible after installation.
All electrode-type boilers shall be marked to show the following:
426.1 Scope
This article covers fixed outdoor electric deicing and snow-melting equipment and the installation of these systems.
(A) Embedded
Embedded in driveways, walks, steps, and other areas.
(B) Exposed
Informational Note: For further information, see ANSI/IEEE 515.1, Standard for the Testing, Design, Installation and Maintenance of Electrical Resistance Trace Heating for Commercial Applications. Also see applicable sections of the IEEE 844/CSA 293 series of standards for fixed outdoor electric deicing and snow-melting equipment
Exposed on drainage systems, bridge structures, roofs, and other structures.426.10 General
Equipment for outdoor electric deicing and snow melting shall be identified as suitable for the environment and installed in accordance with the manufacturer's instructions.426.11 Use
Electric heating equipment shall be installed in such a manner as to be afforded protection from physical damage.
426.12 Thermal Protection
External surfaces of outdoor electric deicing and snow-melting equipment that operate at temperatures exceeding 60°C (140°F) shall be physically guarded isolated , or thermally insulated to protect against contact by personnel in the area.
426.13 Identification
The presence of outdoor electric deicing and snow-melting equipment shall be evident by the posting of appropriate caution signs or markings where clearly visible.
426.14 Special Permission
Fixed outdoor deicing and snow-melting equipment employing methods of construction or installation other than covered by this article shall be permitted only by special permission
(A) Watt Density
Panels or units shall not exceed watts/m2 (120 watts/ft2) of heated area.
(B) Spacing
The spacing between adjacent cable runs is dependent upon the rating of the cable and shall be not less than 25 mm (1 in.) on centers.
(C) Cover
Units, panels, or cables shall be installed as follows:
(D) Secured
Cables , units, and panels shall be secured in place by frames or spreaders or other approved means while the concrete, masonry, or asphalt finish is applied.(E) Expansion and Contraction
Cables , units, and panels shall not be installed where they bridge expansion joints unless provision is made for expansion and contraction.(A) Secured
Heating element assemblies shall be secured to the surface being heated by identified means.
(B) Overtemperature
Where the heating element is not in direct contact with the surface being heated, the design of the heater assembly shall be such that its temperature limitations shall not be exceeded.
(C) Expansion and Contraction
Heating elements and assemblies shall not be installed where they bridge expansion joints unless provision is made for expansion and contraction.
(D) Flexural Capability
Where installed on flexible structures, the heating elements and assemblies shall have a flexural capability that is compatible with the structure.
(B) Splice Connections
The splice connection between the nonheating lead and heating element, within concrete, masonry, or asphalt, shall be located no less than 25 mm (1 in.) and no more than 150 mm (6 in.) from the metal raceway . The length of the nonheating lead from the metal raceway to the splice assembly shall be permitted to be provided without a grounding sheath or braid. Grounding continuity shall be maintained.
(C) Bushings
Insulating bushings shall be used in the concrete, masonry, or asphalt where the leads enter a metal raceway
(D) Expansion and Contraction
Leads shall be protected in expansion joints in accordance with 300.4(H) or installed in accordance with the manufacturer's instructions.
(F) Leads in Junction Boxes
Not less than 150 mm (6 in.) of free nonheating lead shall be within the junction box.
(A) Nonheating Leads
Power supply nonheating leads (cold leads) for resistance elements shall be identified for the temperature encountered. Not less than 150 mm (6 in.) of nonheating leads shall be provided within the junction box. Preassembled factory-supplied and field-assembled nonheating leads on approved heaters shall be permitted to be shortened if the markings specified in 426.25 are retained.
(B) Protection
Nonheating power supply leads shall be enclosed in a rigid conduit, intermediate metal conduit, electrical metallic tubing, or other approved means.
(A) Heating Element Connections
Electrical connections, other than factory connections of heating elements to nonheating elements embedded in concrete, masonry, or asphalt or on exposed surfaces, shall be made with insulated connectors identified for the use.
(B) Circuit Connections
Splices and terminations at the end of the nonheating leads, other than the heating element end, shall be installed in a box or fitting in accordance with 110.14 and 300.15
426.25 Marking
Each factory-assembled heating unit shall be legibly marked within 75 mm (3 in.) of each end of the nonheating leads with the permanent identification symbol, catalog number, and ratings in volts and watts or in volts and amperes.
426.26 Corrosion Protection
Ferrous and nonferrous metal raceways cable armor, cable sheaths , boxes, fittings , supports, and support hardware shall be permitted to be installed in concrete or in direct contact with the earth, or in areas subject to severe corrosive influences, where made of material suitable for the condition, or where provided with corrosion protection identified as suitable for the condition.
426.31 Isolation Transformer
An isolation transformer with a grounded shield between the primary and secondary windings shall be used to isolate the distribution system from the heating system
You will get efficient and thoughtful service from Mingda.
426.32 Voltage Limitations
The secondary winding of the isolation transformer connected to the impedance heating elements shall not have an output voltage greater than 30 volts ac.
426.33 Induced Currents
All current-carrying components shall be installed in accordance with 300.20
426.40 Conductor Ampacity
The current through the electrically insulated conductor inside the ferromagnetic envelope shall be permitted to exceed the ampacity values shown in Table 310.16, provided it is identified as suitable for this use.
426.41 Pull Boxes
Where pull boxes are used, they shall be accessible without excavation by location in suitable vaults or abovegrade. Outdoor pull boxes shall be of watertight construction.
426.42 Single Conductor in Enclosure
The provisions of 300.20 shall not apply to the installation of a single conductor in a ferromagnetic envelope (metal enclosure ).
426.43 Corrosion Protection
Ferromagnetic envelopes, ferrous or nonferrous metal raceways , boxes, fittings , supports, and support hardware shall be permitted to be installed in concrete or in direct contact with the earth, or in areas subjected to severe corrosive influences, where made of material suitable for the condition, or where provided with corrosion protection identified as suitable for the condition. Corrosion protection shall maintain the original wall thickness of the ferromagnetic envelope.
427.11 Use
Electric heating equipment shall be installed in such a manner as to be afforded protection from physical damage.
427.13 Identification
The presence of electrically heated pipelines vessels , or both, shall be evident by the posting of appropriate caution signs or markings at intervals not exceeding 6 m (20 ft) along the pipeline or vessel and on or adjacent to equipment in the piping system that requires periodic servicing.
427.14 Secured
Heating element assemblies shall be secured to the surface being heated by means other than the thermal insulation.
427.15 Not in Direct Contact
Where the heating element is not in direct contact with the pipeline or vessel being heated, means shall be provided to prevent overtemperature of the heating element unless the design of the heating assembly is such that its temperature limitations will not be exceeded.
427.16 Expansion and Contraction
Heating elements and assemblies shall not be installed where they bridge expansion joints unless provisions are made for expansion and contraction.
427.17 Flexural Capability
Where installed on flexible pipelines , the heating elements and assemblies shall have a flexural capability that is compatible with the pipeline
(A) Nonheating Leads
Power supply nonheating leads (cold leads) for resistance elements shall be suitable for the temperature encountered. Not less than 150 mm (6 in.) of nonheating leads shall be provided within the junction box. Preassembled factory-supplied and field-assembled nonheating leads on approved heaters shall be permitted to be shortened if the markings specified in 427.20 are retained.
(C) Interconnecting Leads
Interconnecting nonheating leads connecting portions of the heating system shall be permitted to be covered by thermal insulation in the same manner as the heaters.
(A) Nonheating Interconnections
Nonheating interconnections, where required under thermal insulation, shall be made with insulated connectors identified as suitable for this use.
427.20 Marking
Each factory-assembled heating unit shall be legibly marked within 75 mm (3 in.) of the termination end of all nonheating leads with the permanent identification symbol, catalog number, and ratings in volts and watts or in volts and amperes.
(B) Heating Panels
Heating panels shall have a grounded conductive covering over the heating element and its electrical insulation on the side opposite the side attached to the surface to be heated.427.26 Isolation Transformer
A dual-winding transformer with a grounded shield between the primary and secondary windings shall be used to isolate the distribution system from the heating system
427.28 Induced Currents
All current-carrying components shall be installed in accordance with 300.20
427.29 Grounding
The pipeline vessel , or both, that is being heated and operating at a voltage greater than 30 but not more than 80 shall be grounded at designated points.
427.30 Secondary Conductor Sizing
The ampacity of the conductors connected to the secondary of the transformer shall be at least 100 percent of the total load of the heater.
427.36 Personnel Protection
Induction coils that operate or may operate at a voltage greater than 30 volts ac shall be enclosed in a nonmetallic or split metallic enclosure isolated , or made inaccessible by location to protect personnel in the area.
427.37 Induced Current
Induction coils shall be prevented from inducing circulating currents in surrounding metallic equipment , supports, or structures by shielding, isolation, or insulation of the current paths. Stray current paths shall be bonded to prevent arcing.
427.45 Conductor Ampacity
The ampacity of the electrically insulated conductor inside the ferromagnetic envelope shall be permitted to exceed the values given in Table 310.16, provided it is identified as suitable for this use.
427.46 Pull Boxes
Pull boxes for pulling the electrically insulated conductor in the ferromagnetic envelope shall be permitted to be buried under the thermal insulation, provided their locations are indicated by permanent markings on the insulation jacket surface and on drawings. For outdoor installations, pull boxes shall be of watertight construction.
427.47 Single Conductor in Enclosure
The provisions of 300.20 shall not apply to the installation of a single conductor in a ferromagnetic envelope (metal enclosure ).
430.4 Part-Winding Motors
Each motor-winding connection shall have branch-circuit short-circuit and ground-fault protection rated at not more than one-half that specified by 430.52
Exception: A short-circuit and ground-fault protective device shall be permitted for both windings if the device will allow the motor to start. Where time-delay (dual-element) fuses are used, they shall be permitted to have a rating not exceeding 150 percent of the motor full-load current.
Where separate overload devices are used with a standard part-winding start induction motor, each half of the motor winding shall be individually protected in accordance with 430.32 and 430.37 with a trip current one-half that specified.
430.5 Other Articles
Table 430.5 Other Articles
Equipment/Occupancy Article Section Air-conditioning and refrigerating equipment 440 Capacitors 460.8, 460.9 Commercial garages; aircraft hangars; motor fuel dispensing facilities; bulk storage plants; spray application, dipping, and coating processes; and inhalation anesthetizing locations 511, 513, 514, 515, 516, and 517 Part IV Cranes and hoists 610 Electrically driven or controlled irrigation machines 675 Elevators, dumbwaiters, escalators, moving walks, wheelchair lifts, and stairway chair lifts 620 Fire pumps 695 Hazardous (classified) locations 500503, 505, and 506 Industrial machinery 670 Motion picture projectors 540.11 and 540.20 Motion picture and television studios and similar locations 530 Resistors and reactors 470 Theaters, audience areas of motion picture and television studios, and similar locations 520.48 Transformers and transformer vaults 450Motors and controllers shall also comply with the applicable provisions of Table 430.5.
(A) General Motor Applications
For general motor applications, current ratings shall be determined based on 430.6(A)(1) and (A)(2).
(2) Nameplate Values
Separate motor overload protection shall be based on the motor nameplate current rating.
(A) Usual Motor Applications
Informational Note: See 430.7(B)
Informational Note: Motor design letter definitions are found in ANSI/NEMA MG 1-, Motors and Generators, Part 1, Definitions, and in IEEE 100-, Standard Dictionary of Electrical and Electronic Terms.
A motor shall be marked with the following information:
(B) Locked-Rotor Indicating Code Letters
The code letter indicating motor input with locked rotor shall be in an individual block on the nameplate, properly designated.
Table 430.7(B) Locked-Rotor Indicating Code Letters Code Letter Kilovolt-Amperes per Horsepower with Locked Rotor A 03.14 B 3.153.54 C 3.553.99 D 4.04.49 E 4.54.99 F 5.05.59 G 5.66.29 H 6.37.09 J 7.17.99 K 8.08.99 L 9.09.99 M 10.011.19 N 11.212.49 P 12.513.99 R 14.015.99 S 16.017.99 T 18.019.99 U 20.022.39 V 22.4 and upCode letters marked on motor nameplates to show motor input with locked rotor shall be in accordance with Table 430.7(B).
(1) Multispeed Motors
Exception: Constant horsepower multispeed motors shall be marked with the code letter giving the highest locked-rotor kilovolt-ampere (kVA) per horsepower (hp).
Multispeed motors shall be marked with the code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) for the highest speed at which the motor can be started.
(2) Single-Speed Motors
Single-speed motors starting on wye connection and running on delta connections shall be marked with a code letter corresponding to the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) for the wye connection.
(3) Dual-Voltage Motors
Dual- voltage motors that have a different locked-rotor kilovolt-ampere (kVA) per horsepower (hp) on the two voltages shall be marked with the code letter for the voltage giving the highest locked-rotor kilovolt-ampere (kVA) per horsepower (hp).
(4) 50/60 Hz Motors
Motors with 50-and 60-Hz ratings shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) on 60 Hz.
(5) Part-Winding Motors
Part-winding start motors shall be marked with a code letter designating the locked-rotor kilovolt-ampere (kVA) per horsepower (hp) that is based on the locked-rotor current for the full winding of the motor.
(C) Torque Motors
Torque motors are rated for operation at standstill and shall be marked in accordance with 430.7(A) , except that locked-rotor torque shall replace horsepower.
(1) Factory-Wired
Multimotor and combination-load equipment shall be provided with a visible nameplate marked with the manufacturer's name, the rating in volts, frequency, number of phases, minimum supply circuit conductor ampacity , and the maximum ampere rating of the circuit short-circuit and ground-fault protective device . The conductor ampacity shall be calculated in accordance with 430.24 and counting all of the motors and other loads that will be operated at the same time. The short-circuit and ground-fault protective device rating shall not exceed the value calculated in accordance with 430.53 . Multimotor equipment for use on two or more circuits shall be marked with the preceding information for each circuit.
(2) Not Factory-Wired
Where the equipment is not factory-wired and the individual nameplates of motors and other loads are visible after assembly of the equipment , the individual nameplates shall be permitted to serve as the required marking.
(A) Markings
Terminals of motors and controllers shall be suitably marked or colored where necessary to indicate the proper connections.430.11 Protection Against Liquids
Suitable guards or enclosures shall be provided to protect exposed current-carrying parts of motors and the insulation of motor leads where installed directly under equipment , or in other locations where dripping or spraying oil, water, or other liquid is capable of occurring, unless the motor is designed for the existing conditions.
(A) Material
Exception: In other than hazardous (classified) locations, substantial, nonmetallic, noncombustible housings shall be permitted, provided an internal grounding means between the motor frame and the equipment grounding connection is incorporated within the housing.
Where motors are provided with terminal housings, the housings shall be of metal and of substantial construction.
(B) Dimensions and Space Wire-to-Wire Connections
Table 430.12(B) Terminal Housings Wire-to-Wire Connections Motors 275 mm (11 in.) in Diameter or Less Horsepower Cover Opening Minimum Dimension Usable Volume Minimum mm in. cm3 in.3 1 and smallera 41 15/8 170 10.5 11/2, 2, and 3b 45 13/4 275 16.8 5 and 71/2 50 2 365 22.4 10 and 15 65 21/2 595 36.4 Motors Over 275 mm (11 in.) in Diameter Alternating-Current Motors Maximum Full Load Current for 3-Phase Motors with Maximum of 12 Leads (Amperes) Terminal Box Cover Opening Minimum Dimension Usable Volume Minimum Typical Maximum Horsepower 3-Phase mm in. cm3 in.3 230 Volt 460 Volt 45 65 2.5 595 36.4 15 30 70 84 3.3 1,265 77 25 50 110 100 4.0 2,295 140 40 75 160 125 5.0 4,135 252 60 125 250 150 6.0 7,380 450 100 200 400 175 7.0 13,775 840 150 300 600 200 8.0 25,255 250 500 Direct-Current Motors Maximum Full-Load Current for Motors with Maximum of 6 Leads (Amperes) Terminal Box Minimum Dimensions Usable Volume Minimum mm in. cm3 in.3 68 65 2.5 425 26 105 84 3.3 900 55 165 100 4.0 1,640 100 240 125 5.0 2,950 180 375 150 6.0 5,410 330 600 175 7.0 9,840 600 900 200 8.0 18,040 1,100 Note: Auxiliary leads for such items as brakes, thermostats, space heaters, and exciting fields shall be permitted to be neglected if their current-carrying area does not exceed 25 percent of the current-carrying area of the machine power leads. aFor motors rated 1 hp and smaller, and with the terminal housing partially or wholly integral with the frame or end shield, the volume of the terminal housing shall not be less than 18.0 cm3 (1.1 in.3) per wire-to-wire connection. The minimum cover opening dimension is not specified. bFor motors rated 11/2, 2, and 3 hp, and with the terminal housing partially or wholly integral with the frame or end shield, the volume of the terminal housing shall not be less than 23.0 cm3 (1.4 in.3) per wire-to-wire connection. The minimum cover opening dimension is not specified.Where these terminal housings enclose wire -to- wire connections, they shall have minimum dimensions and usable volumes in accordance with Table 430.12(B).
430.13 Bushing
Informational Note: For conductors exposed to deteriorating agents, see 310.10(F)
Where wires pass through an opening in an enclosure , conduit box, or barrier, a bushing shall be used to protect the conductors from the edges of openings having sharp edges. The bushing shall have smooth, well-rounded surfaces where it may be in contact with the conductors. If used where oils, greases, or other contaminants may be present, the bushing shall be made of material not deleteriously affected.
(A) Ventilation and Maintenance
Exception: Ventilation shall not be required for submersible types of motors.
Motors shall be located so that adequate ventilation is provided and so that maintenance, such as lubrication of bearings and replacing of brushes, can be readily accomplished.
(B) Open Motors
Exception: Installation of these motors on wooden floors or supports shall be permitted.
Open motors that have commutators or collector rings shall be located or protected so that sparks cannot reach adjacent combustible material.
430.16 Exposure to Dust Accumulations
Informational Note: Especially severe conditions may require the use of enclosed pipe- ventilated motors, or enclosure in separate dusttight rooms, properly ventilated from a source of clean air.
In locations where dust or flying material collects on or in motors in such quantities as to seriously interfere with the ventilation or cooling of motors and thereby cause dangerous temperatures, suitable types of enclosed motors that do not overheat under the prevailing conditions shall be used.
430.22 Single Motor
Conductors that supply a single motor used in a continuous duty application shall have an ampacity of not less than 125 percent of the motor full-load current rating, as determined by 430.6(A)(1) , or not less than specified in 430.22(A) through (G).
(A) Direct-Current Motor-Rectifier Supplied
For dc motors operating from a rectified power supply, the conductor ampacity on the input of the rectifier shall not be less than 125 percent of the rated input current to the rectifier. For dc motors operating from a rectified single-phase power supply, the conductors between the field wiring output terminals of the rectifier and the motor shall have an ampacity of not less than the following percentages of the motor full-load current rating:
(B) Multispeed Motor
For a multispeed motor, the selection of branch-circuit conductors on the line side of the controller shall be based on the highest of the full-load current ratings shown on the motor nameplate. The ampacity of the branch-circuit conductors between the controller and the motor shall not be less than 125 percent of the current rating of the winding(s) that the conductors energize.
(C) Wye-Start, Delta-Run Motor
Informational Note: The individual motor circuit conductors of a wye-start, delta-run connected motor carry 58 percent of the rated load current. The multiplier of 72 percent is obtained by multiplying 58 percent by 1.25.
For a wye-start, delta-run connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125 percent of the motor full-load current as determined by 430.6(A)(1) . The ampacity of the conductors between the controller and the motor shall not be less than 72 percent of the motor full-load current rating as determined by 430.6(A)(1)
(D) Part-Winding Motor
Informational Note: The multiplier of 62.5 percent is obtained by multiplying 50 percent by 1.25.
For a part-winding connected motor, the ampacity of the branch-circuit conductors on the line side of the controller shall not be less than 125 percent of the motor full-load current as determined by 430.6(A)(1) . The ampacity of the conductors between the controller and the motor shall not be less than 62.5 percent of the motor full-load current rating as determined by 430.6(A)(1)
(G) Conductors for Small Motors
Conductors for small motors shall not be smaller than 14 AWG unless otherwise permitted in 430.22(G)(1) or (G)(2).
(1) 18 AWG Copper
18 AWG individual copper conductors installed in a cabinet or enclosure , copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted, under either of the following sets of conditions:
(2) 16 AWG Copper
16 AWG individual copper conductors installed in a cabinet or enclosure , copper conductors that are part of a jacketed multiconductor cable assembly, or copper conductors in a flexible cord shall be permitted under either of the following sets of conditions:
(A) Continuous Duty
For continuous duty , the conductors connecting the secondary of a wound-rotor ac motor to its controller shall have an ampacity not less than 125 percent of the full-load secondary current of the motor.
430.28 Feeder Taps
Exception: Feeder taps over 7.5 m (25 ft) long. In high-bay manufacturing buildings [over 11 m (35 ft) high at walls], where conditions of maintenance and supervision ensure that only qualified persons service the systems, conductors tapped to a feeder shall be permitted to be not over 7.5 m (25 ft) long horizontally and not over 30.0 m (100 ft) in total length where all of the following conditions are met:
430.31 General
Informational Note No. 1: See Informative Annex D, Example No. D8.
Informational Note No. 2: See the definition of Overload in Article 100
These provisions shall not require overload protection where a power loss would cause a hazard, such as in the case of fire pumps.
Informational Note: For protection of fire pump supply conductors, see 695.7
Part III shall not apply to motor circuits rated over volts, nominal.
Informational Note: For over volts, nominal, see Part XI.
Part III specifies overload devices intended to protect motors, motor- control apparatus, and motor branch-circuit conductors against excessive heating due to motor overloads and failure to start.
(1) Separate Overload Device
Motors with a marked service factor 1.15 or greater 125% Motors with a marked temperature rise 40°C or less 125% All other motors 115%Modification of this value shall be permitted as provided in 430.32(C) . For a multispeed motor, each winding connection shall be considered separately.
Where a separate motor overload device is connected so that it does not carry the total current designated on the motor nameplate, such as for wye-delta starting, the proper percentage of nameplate current applying to the selection or setting of the overload device shall be clearly designated on the equipment , or the manufacturer's selection table shall take this into account.
Informational Note: Where power factor correction capacitors are installed on the load side of the motor overload device , see 460.9
A separate overload device that is responsive to motor current. This device shall be selected to trip or shall be rated at no more than the following percent of the motor nameplate full-load current rating:
(3) Integral With Motor
A protective device integral with a motor that will protect the motor against damage due to failure to start shall be permitted if the motor is part of an approved assembly that does not normally subject the motor to overloads
(4) Larger Than Horsepower
For motors larger than hp, a protective device having embedded temperature detectors that cause current to the motor to be interrupted when the motor attains a temperature rise greater than marked on the nameplate in an ambient temperature of 40°C.
(B) One Horsepower or Less, Automatically Started
Any motor of 1 hp or less that is started automatically shall be protected against overload by one of the following means.
(3) Integral With Motor
A protective device integral with a motor that protects the motor against damage due to failure to start shall be permitted (1) if the motor is part of an approved assembly that does not subject the motor to overloads , or (2) if the assembly is also equipped with other safety controls (such as the safety combustion controls on a domestic oil burner) that protect the motor against damage due to failure to start. Where the assembly has safety controls that protect the motor, it shall be so indicated on the nameplate of the assembly where it will be visible after installation.
(4) Impedance-Protected
1/20 hp, such as clock motors, series motors, and so forth, and also some larger motors such as torque motors, come within this classification. It does not include split-phase motors havingInformational Note: Many ac motors of less thanhp, such as clock motors, series motors, and so forth, and also some larger motors such as torque motors, come within this classification. It does not include split-phase motors having automatic switches that disconnect the starting windings.
If the impedance of the motor windings is sufficient to prevent overheating due to failure to start, the motor shall be permitted to be protected as specified in 430.32(D)(2) (a) for manually started motors if the motor is part of an approved assembly in which the motor will limit itself so that it will not be dangerously overheated.
(C) Selection of Overload Device
Motors with marked service factor 1.15 or greater 140% Motors with a marked temperature rise 40°C or less 140% All other motors 130%If not shunted during the starting period of the motor as provided in 430.35 , the overload device shall have sufficient time delay to permit the motor to start and accelerate its load.
Informational Note: A Class 20 overload relay will provide a longer motor acceleration time than a Class 10 or Class 10A overload relay. A Class 30 overload relay will provide a longer motor acceleration time than a Class 20 overload relay. Use of a higher class overload relay may preclude the need for selection of a higher trip current.
Where the sensing element or setting or sizing of the overload device selected in accordance with 430.32(A)(1) and 430.32(B)(1) is not sufficient to start the motor or to carry the load, higher size sensing elements or incremental settings or sizing shall be permitted to be used, provided the trip current of the overload device does not exceed the following percentage of motor nameplate full-load current rating:
(A) Nonautomatically Started
For a nonautomatically started motor, the overload protection shall be permitted to be shunted or cut out of the circuit during the starting period of the motor if the device by which the overload protection is shunted or cut out cannot be left in the starting position and if fuses or inverse time circuit breakers rated or set at not over 400 percent of the full-load current of the motor are located in the circuit so as to be operative during the starting period of the motor.
(B) Automatically Started
Exception: The motor overload protection shall be permitted to be shunted or cut out during the starting period on an automatically started motor where the following apply:
The motor overload protection shall not be shunted or cut out during the starting period if the motor is automatically started.
(D) Time Delay
The branch-circuit short-circuit and ground-fault protective device protecting a circuit to which a motor or motor-operated appliance is connected shall have sufficient time delay to permit the motor to start and accelerate its load.
430.43 Automatic Restarting
A motor overload device that can restart a motor automatically after overload tripping shall not be installed unless approved for use with the motor it protects. A motor overload device that can restart a motor automatically after overload tripping shall not be installed if automatic restarting of the motor can result in injury to persons.
430.44 Orderly Shutdown
If immediate automatic shutdown of a motor by a motor overload protective device (s) would introduce additional or increased hazard(s) to a person(s) and continued motor operation is necessary for safe shutdown of equipment or process, a motor overload sensing device (s) complying with Part III of this article shall be permitted to be connected to a supervised alarm instead of causing immediate interruption of the motor circuit, so that corrective action or an orderly shutdown can be initiated.
430.52 Rating or Setting for Individual Motor Circuit
(1) In Accordance With Table 430.52
Exception No. 1: Where the values for branch-circuit short-circuit and ground-fault protective devices determined by Table 430.52 do not correspond to the standard sizes or ratings of fuses , nonadjustable circuit breakers , thermal protective devices , or possible settings of adjustable circuit breakers , a higher size, rating, or possible setting that does not exceed the next higher standard ampere rating shall be permitted.
Exception No. 2: Where the rating specified in Table 430.52, or the rating modified by Exception No. 1, is not sufficient for the starting current of the motor:
Informational Note: See Informative Annex D, Example D8, and Figure 430.1.
A protective device that has a rating or setting not exceeding the value calculated according to the values given in Table 430.52 shall be used.
(4) Multispeed Motor
Exception: For a multispeed motor, a single short-circuit and ground-fault protective device shall be permitted to be used and sized according to the full-load current of the highest current winding, where all of the following conditions are met:
For a multispeed motor, a single short-circuit and ground-fault protective device shall be permitted for two or more windings of the motor, provided the rating of the protective device does not exceed the above applicable percentage of the nameplate rating of the smallest winding protected.
(6) Self-Protected Combination Controller
Informational Note: Proper application of self-protected combination controllers on 3-phase systems, other than solidly grounded wye, particularly on corner grounded delta systems, considers the self-protected combination controllers ' individual pole-interrupting capability.
A listed self-protected combination controller shall be permitted in lieu of the devices specified in Table 430.52. Adjustable instantaneous-trip settings shall not exceed percent of full-load motor current for other than Design B energy-efficient motors and not more than percent of full-load motor current for Design B energy-efficient motors.
(7) Motor Short-Circuit Protector
Informational Note: A motor short-circuit protector, as used in this section, is a fused device and is not an instantaneous trip circuit breaker
A motor short-circuit protector shall be permitted in lieu of devices listed in Table 430.52 if the motor short-circuit protector is part of a listed combination motor controller having coordinated motor overload protection and short-circuit and ground-fault protection in each conductor and it will open the circuit at currents exceeding percent of motor full-load current for other than Design B energy-efficient motors and percent of motor full-load motor current for Design B energy-efficient motors.
430.57 Size of Fuseholder
Exception: Where fuses having time delay appropriate for the starting characteristics of the motor are used, it shall be permitted to use fuseholders sized to fit the fuses that are used.
Where fuses are used for motor branch-circuit short-circuit and ground-fault protection, the fuseholders shall not be of a smaller size than required to accommodate the fuses specified by Table 430.52.
430.61 General
Informational Note: See Informative Annex D, Example D8.
Part V specifies protective devices intended to protect feeder conductors supplying motors against overcurrents due to short circuits or grounds
430.71 General
Part VI contains modifications of the general requirements and applies to the particular conditions of motor control circuits
(5) Other Means
Protection shall be permitted to be provided by other approved means.
430.81 General
Part VII is intended to require suitable controllers for all motors.
(A) Starting and Stopping
Each controller shall be capable of starting and stopping the motor it controls and shall be capable of interrupting the locked-rotor current of the motor.
(B) Autotransformer
An autotransformer starter shall provide an "off" position, a running position, and at least one starting position. It shall be designed so that it cannot rest in the starting position or in any position that will render the overload device in the circuit inoperative.
(C) Rheostats
Rheostats shall be in compliance with the following:
430.83 Ratings
The controller shall have a rating as specified in 430.83(A) , unless otherwise permitted in 430.83(B) or (C), or as specified in (D), under the conditions specified.
(3) Molded Case Switch
A molded case switch rated in amperes shall be permitted as a controller for all motors.
(C) Stationary Motors of 2 Horsepower or Less
For stationary motors rated at 2 hp or less and 300 volts or less, the controller shall be permitted to be either of the following:
430.88 Adjustable-Speed Motors
Exception: Starting under a weakened field shall be permitted where the motor is designed for such starting.
Adjustable-speed motors that are controlled by means of field regulation shall be equipped and connected so that they cannot be started under a weakened field.
430.89 Speed Limitation
Exception: Separate speed-limiting devices or means shall not be required under either of the following conditions:
Machines of the following types shall be provided with speed-limiting devices or other speed-limiting means:
(A) Support and Arrangement
Exception: Conductors shall be permitted to travel horizontally through vertical sections where such conductors are isolated from the busbars by a barrier.
Busbars shall be protected from physical damage and be held firmly in place. Other than for required interconnections and control wiring, only those conductors that are intended for termination in a vertical section shall be located in that section.
(B) Phase Arrangement
Exception: Rear-mounted units connected to a vertical bus that is common to front-mounted units shall be permitted to have a C, B, A phase arrangement where properly identified
The phase arrangement on 3-phase horizontal common power and vertical buses shall be A, B, C from front to back, top to bottom, or left to right, as viewed from the front of the motor control center . The B phase shall be that phase having the higher voltage to ground on 3-phase, 4- wire , delta-connected systems. Other busbar arrangements shall be permitted for additions to existing installations and shall be marked.
(D) Spacings
Table 430.97(D) Minimum Spacing Between Bare Metal Parts
Nominal Voltage Opposite Polarity Where Mounted on the Same Surface Opposite Polarity Where Held Free in Air Live Parts to Ground mm in. mm in. mm in. Not over 125 volts, nominal 19.1 3/4 12.7 1/2 12.7 1/2 Not over 250 volts, nominal 31.8 11/4 19.1 3/4 12.7 1/2 Not over 600 volts, nominal 50.8 2 25.4 1 25.4 1Spacings between motor control center bus terminals and other bare metal parts shall not be less than specified in Table 430.97(D).
430.101 General
Part IX is intended to require disconnecting means capable of disconnecting motors and controllers from the circuit.
430.104 To Be Indicating
The disconnecting means shall plainly indicate whether it is in the open (off) or closed (on) position.
(3) Molded Case Switch
A listed molded case switch.
(E) Isolating Switches
For stationary motors rated at more than 40 hp dc or 100 hp ac, the disconnecting means shall be permitted to be a general-use or isolating switch where plainly marked "Do not operate under load."
(A) General
Exception: A listed unfused motor-circuit switch having a horsepower rating not less than the motor horsepower shall be permitted to have an ampere rating less than 115 percent of the full-load current rating of the motor.
The disconnecting means for motor circuits rated volts, nominal, or less shall have an ampere rating not less than 115 percent of the full-load current rating of the motor.
(B) For Torque Motors
Disconnecting means for a torque motor shall have an ampere rating of at least 115 percent of the motor nameplate current.(C) For Combination Loads
Where two or more motors are used together or where one or more motors are used in combination with other loads, such as resistance heaters, and where the combined load may be simultaneous on a single disconnecting means , the ampere and horsepower ratings of the combined load shall be determined as follows.
(1) Horsepower Rating
The full-load current equivalent to the horsepower rating of each motor shall be selected from Table 430.247, Table 430.248 Table 430.249 , or Table 430.250 . These full-load currents shall be added to the rating in amperes of other loads to obtain an equivalent full-load current for the combined load.
The locked-rotor current equivalent to the horsepower rating of each motor shall be selected from Table 430.251(A) or Table 430.251(B) . The locked-rotor currents shall be added to the rating in amperes of other loads to obtain an equivalent locked-rotor current for the combined load. Where two or more motors or other loads cannot be started simultaneously, the largest sum of locked-rotor currents of a motor or group of motors that can be started simultaneously and the full-load currents of other concurrent loads shall be permitted to be used to determine the equivalent locked-rotor current for the simultaneous combined loads. In cases where different current ratings are obtained when applying these tables, the largest value obtained shall be used.
Exception: Where part of the concurrent load is resistance load, and where the disconnecting means is a switch rated in horsepower and amperes, the switch used shall be permitted to have a horsepower rating that is not less than the combined load of the motor(s), if the ampere rating of the switch is not less than the locked-rotor current of the motor(s) plus the resistance load.
The rating of the disconnecting means shall be determined from the sum of all currents, including resistance loads, at the full-load condition and also at the locked-rotor condition. The combined full-load current and the combined locked-rotor current so obtained shall be considered as a single motor for the purpose of this requirement as follows.
(2) Ampere Rating
Exception: A listed nonfused motor-circuit switch having a horsepower rating equal to or greater than the equivalent horsepower of the combined loads, determined in accordance with 430.110(C)(1) , shall be permitted to have an ampere rating less than 115 percent of the sum of all currents at the full-load condition.
The ampere rating of the disconnecting means shall not be less than 115 percent of the sum of all currents at the full-load condition determined in accordance with 430.110(C)(1)
(B) Type
The device shall be one of the types specified in 430.111(B)(1) , (B)(2), or (B)(3).
(1) Air-Break Switch
An air-break switch, operable directly by applying the hand to a lever or handle.
(3) Oil Switch
An oil switch used on a circuit whose rating does not exceed volts or 100 amperes, or by special permission on a circuit exceeding this capacity where under expert supervision. The oil switch shall be permitted to be both power and manually operable.
430.120 General
The installation provisions of Part I through Part IX are applicable unless modified or supplemented by Part X.
(A) Branch/Feeder Circuit Conductors
Informational Note No. 1: Power conversion equipment can have multiple power ratings and corresponding input currents.
Informational Note No. 2: Circuit conductors on the output of an adjustable-speed drive system are susceptible to breakdown under certain conditions due to the characteristics of the output waveform of the drive. Factors affecting the conductors include but are not limited to the output voltage , frequency, and current, the length of the conductors, the spacing between the conductors, and the dielectric strength of the conductor insulation. Methods to mitigate breakdown include consideration of one or more of these factors.
Circuit conductors supplying power conversion equipment included as part of an adjustable-speed drive system shall have an ampacity not less than 125 percent of the rated input current to the power conversion equipment
(B) Output Conductors
Exception: If the power conversion equipment is listed and marked as "Suitable for Output Motor Conductor Protection," the conductor between the power conversion equipment and the motor shall have an ampacity equal to or greater than the larger of:
Informational Note: The minimum ampacity required of output conductors is often different than that of the conductors supplying the power conversion equipment . See 430.130 and 430.131 for branch circuit protection requirements.
The conductors between the power conversion equipment and the motor shall have an ampacity equal to or larger than 125 percent of the motor full-load current as determined by 430.6(A) or (B).
(C) Bypass Device
For an adjustable-speed drive system that utilizes a bypass device , the conductor ampacity shall not be less than required by 430.6 . The ampacity of circuit conductors supplying power conversion equipment included as part of an adjustable-speed drive system that utilizes a bypass device shall be the larger of either of the following:
(B) Bypass Circuits
For adjustable-speed drive systems that utilize a bypass device to allow motor operation at rated full-load speed, motor overload protection as described in Article 430 , Part III, shall be provided in the bypass circuit.
(A) General
Exception to (2): Thermal memory retention upon shutdown or power loss is not required for continuous duty loads.
Informational Note: The relationship between motor current and motor temperature changes when the motor is operated by an adjustable-speed drive. In certain applications, overheating of motors can occur when operated at reduced speed, even at current levels less than a motor's rated full-load current. The overheating can be the result of reduced motor cooling when its shaft-mounted fan is operating less than rated nameplate RPM. As part of the analysis to determine whether overheating will occur, it is necessary to consider the continuous torque capability curves for the motor given the application requirements. This will assist in determining whether the motor overload protection will be able, on its own, to provide protection against overheating. These overheating protection requirements are only intended to apply to applications where an adjustable-speed drive, as defined in Article 100 , is used.
For motors that utilize external forced air or liquid cooling systems, overtemperature can occur if the cooling system is not operating. Although this issue is not unique to adjustable speed applications, externally cooled motors are most often encountered with such applications. In these instances, overtemperature protection using direct temperature sensing is recommended [i.e., 430.126(A)(1), (A)(3), or (A)(4)], or additional means should be provided to ensure that the cooling system is operating (flow or pressure sensing, interlocking of adjustable-speed drive system and cooling system, etc.).
Adjustable-speed drive systems shall protect against motor overtemperature conditions where the motor is not rated to operate at the nameplate rated current over the speed range required by the application. This protection shall be provided in addition to the conductor protection required in 430.32 . Protection shall be provided by one of the following means.
(B) Multiple Motor Applications
For multiple motor applications, individual motor overtemperature protection shall be provided as required in 430.126(A)
430.128 Disconnecting Means
The disconnecting means shall be permitted to be in the incoming line to the conversion equipment and shall have a rating not less than 115 percent of the rated input current of the conversion unit.
430.221 General
Part XI recognizes the additional hazard due to the use of higher voltages . It adds to or amends the other provisions of this article.
430.223 Raceway Connection to Motors
enclosure.Flexible metal conduit or liquidtight flexible metal conduit not exceeding 1.8 m (6 ft) in length shall be permitted to be employed for raceway connection to a motor terminal
(A) General
Exception: Where a motor is critical to an operation and the motor should operate to failure if necessary to prevent a greater hazard to persons, the sensing device (s) shall be permitted to be connected to a supervised annunciator or alarm instead of interrupting the motor circuit.
Each motor circuit shall include coordinated protection to automatically interrupt overload and fault currents in the motor, the motor-circuit conductors, and the motor control apparatus.
(2) Reclosing
Exception: Automatic reclosing of a circuit shall be permitted where the circuit is exposed to transient faults and where such automatic reclosing does not create a hazard to persons.
Fault-current interrupting devices shall not automatically reclose the circuit.430.231 General
Part XII specifies that live parts shall be protected in an approved manner for the hazard involved.
430.241 General
Part XIII specifies the grounding of exposed noncurrent-carrying metal parts, likely to become energized , of motor and controller frames to prevent a voltage aboveground in the event of accidental contact between energized parts and frames . Insulation, isolation, or guarding are suitable alternatives to grounding of motors under certain conditions.
Part XIV Tables
Table 430.247 Full-Load Current in Amperes, Direct-Current Motors
The following values of full-load currents* are for motors running at base speed.
Horsepower Armature Voltage Rating* 90 Volts 120 Volts 180 Volts 240 Volts 500 Volts 550 Volts 1/4 4.0 3.1 2.0 1.6 1/3 5.2 4.1 2.6 2.0 1/2 6.8 5.4 3.4 2.7 3/4 9.6 7.6 4.8 3.8 1 12.2 9.5 6.1 4.7 11/2 13.2 8.3 6.6 2 17 10.8 8.5 3 25 16 12.2 5 40 27 20 71/2 58 29 13.6 12.2 10 76 38 18 16 15 55 27 24 20 72 34 31 25 89 43 38 30 106 51 46 40 140 67 61 50 173 83 75 60 206 99 90 75 255 123 111 100 341 164 148 125 425 205 185 150 506 246 222 200 675 330 294 *These are average dc quantities. Table 430.248 Full-Load Currents in Amperes, Single-Phase Alternating-Current MotorsThe following values of full-load currents are for motors running at usual speeds and motors with normal torque characteristics. The voltages listed are rated motor voltages . The currents listed shall be permitted for system voltage ranges of 110 to 120 and 220 to 240 volts.
Horsepower 115 Volts 200 Volts 208 Volts 230 Volts 1/6 4.4 2.5 2.4 2.2 1/4 5.8 3.3 3.2 2.9 1/3 7.2 4.1 4.0 3.6 1/2 9.8 5.6 5.4 4.9 3/4 13.8 7.9 7.6 6.9 1 16 9.2 8.8 8.0 11/2 20 11.5 11.0 10 2 24 13.8 13.2 12 3 34 19.6 18.7 17 5 56 32.2 30.8 28 71/2 80 46.0 44.0 40 10 100 57.5 55.0 50 Table 430.249 Full-Load Current, Two-Phase Alternating-Current Motors (4-Wire)The following values of full-load current are for motors running at speeds usual for belted motors and motors with normal torque characteristics. Current in the common conductor of a 2-phase, 3- wire system will be 1.41 times the value given. The voltages listed are rated motor voltages . The currents listed shall be permitted for system voltage ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.
Horsepower Induction-Type Squirrel Cage and Wound Rotor (Amperes) 115 Volts 230 Volts 460 Volts 575 Volts Volts 1/2 4.0 2.0 1.0 0.8 3/4 4.8 2.4 1.2 1.0 1 6.4 3.2 1.6 1.3 11/2 9.0 4.5 2.3 1.8 2 11.8 5.9 3.0 2.4 3 8.3 4.2 3.3 5 13.2 6.6 5.3 71/2 19 9.0 8.0 10 24 12 10 15 36 18 14 20 47 23 19 25 59 29 24 30 69 35 28 40 90 45 36 50 113 56 45 60 133 67 53 14 75 166 83 66 18 100 218 109 87 23 125 270 135 108 28 150 312 156 125 32 200 416 208 167 43 Table 430.250 Full-Load Current, Three-Phase Alternating-Current MotorsThe following values of full-load currents are typical for motors running at speeds usual for belted motors and motors with normal torque characteristics. The voltages listed are rated motor voltages . The currents listed shall be permitted for system voltage ranges of 110 to 120, 220 to 240, 440 to 480, and 550 to 600 volts.
Horsepower Induction-Type Squirrel Cage and Wound Rotor (Amperes) Synchronous-Type Unity Power Factor* (Amperes) 115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts Volts 230 Volts 460 Volts 575 Volts Volts 1/2 4.4 2.5 2.4 2.2 1.1 0.9 3/4 6.4 3.7 3.5 3.2 1.6 1.3 1 8.4 4.8 4.6 4.2 2.1 1.7 11/2 12.0 6.9 6.6 6.0 3.0 2.4 2 13.6 7.8 7.5 6.8 3.4 2.7 3 11.0 10.6 9.6 4.8 3.9 5 17.5 16.7 15.2 7.6 6.1 71/2 25.3 24.2 22 11 9 10 32.2 30.8 28 14 11 15 48.3 46.2 42 21 17 20 62.1 59.4 54 27 22 25 78.2 74.8 68 34 27 53 26 21 30 92 88 80 40 32 63 32 26 40 120 114 104 52 41 83 41 33 50 150 143 130 65 52 104 52 42 60 177 169 154 77 62 16 123 61 49 12 75 221 211 192 96 77 20 155 78 62 15 100 285 273 248 124 99 26 202 101 81 20 125 359 343 312 156 125 31 253 126 101 25 150 414 396 360 180 144 37 302 151 121 30 200 552 528 480 240 192 49 400 201 161 40 250 302 242 60 300 361 289 72 350 414 336 83 400 477 382 95 450 515 412 103 500 590 472 118 *For 90 and 80 percent power factor, the figures shall be multiplied by 1.1 and 1.25, respectively. Table 430.251(A) Conversion Table of Single-Phase Locked-Rotor Currents for Selection of Disconnecting Means and Controllers as Determined from Horsepower and Voltage Rating440.12,For use only with 430.110 440.41 , and 455.8(C)
Rated Horsepower Maximum Locked-Rotor Current in Amperes, Single Phase 115 Volts 208 Volts 230 Volts 1/2 58.8 32.5 29.4 3/4 82.8 45.8 41.4 1 96 53 48 11/2 120 66 60 2 144 80 72 3 204 113 102 5 336 186 168 71/2 480 265 240 10 332 300 Table 430.251(B) Conversion Table of Polyphase Design B, C, and D Maximum Locked-Rotor Currents for Selection of Disconnecting Means and Controllers as Determined from Horsepower and Voltage Rating and Design Letter440.12,For use only with 430.110 440.41 , and 455.8(C)
Rated Horsepower Maximum Motor Locked-Rotor Current in Amperes, Two-and Three-Phase, Design B, C, and D* 115 Volts 200 Volts 208 Volts 230 Volts 460 Volts 575 Volts B, C, D B, C, D B, C, D B, C, D B, C, D B, C, D 1/2 40 23 22.1 20 10 8 3/4 50 28.8 27.6 25 12.5 10 1 60 34.5 33 30 15 12 11/2 80 46 44 40 20 16 2 100 57.5 55 50 25 20 3 73.6 71 64 32 25.6 5 105.8 102 92 46 36.8 71/2 146 140 127 63.5 50.8 10 186.3 179 162 81 64.8 15 267 257 232 116 93 20 334 321 290 145 116 25 420 404 365 183 146 30 500 481 435 218 174 40 667 641 580 290 232 50 834 802 725 363 290 60 962 870 435 348 75 543 434 100 725 580 125 908 726 150 868 200 250 300 350 400 450 500 *Design A motors are not limited to a maximum starting current or locked rotor current.(A) Article 430
These provisions are in addition to, or amendatory of, the provisions of Article 430 and other articles in this Code, which apply except as modified in this article.
440.5 Marking on Controllers
controller shall be marked with the manufacturer's name, trademark, or symbol; identifying designation; voltage ; phase; full-load and locked-rotor current (or horsepower) rating; and other data as may be needed to properly indicate the motor-compressor for which it is suitable.440.8 Single Machine
An air-conditioning or refrigerating system shall be considered to be a single machine under the provisions of 430.87, Exception No. 1, and 430.112 , Exception. The motors shall be permitted to be located remotely from each other.
(1) Ampere Rating
Exception: A listed unfused motor circuit switch, without fuseholders, having a horsepower rating not less than the equivalent horsepower determined in accordance with 440.12(A)(2) shall be permitted to have an ampere rating less than 115 percent of the specified current.
The ampere rating shall be at least 115 percent of the nameplate rated-load current or branch-circuit selection current , whichever is greater.
(2) Full-Load Current Equivalent
Exception: A listed unfused motor circuit switch, without fuseholders, having a horsepower rating not less than the equivalent horsepower determined by 440.12(B)(1) shall be permitted to have an ampere rating less than 115 percent of the sum of all currents.
The ampere rating of the disconnecting means shall be at least 115 percent of the sum of all currents at the rated-load condition determined in accordance with 440.12(B)(1)
(D) Disconnecting Means
Every disconnecting means in the refrigerant motor-compressor circuit between the point of attachment to the feeder and the point of connection to the refrigerant motor-compressor shall comply with the requirements of 440.12
440.31 General
equipment.These articles shall not apply to integral conductors of motors, to motor controllers and the like, or to conductors that form an integral part of approved
Part IV and Article 310 specify ampacities of conductors required to carry the motor current without overheating under the conditions specified, except as modified in 440.6(A) , Exception No. 1.
440.33 Motor-Compressor(s) With or Without Additional Motor Loads
Exception No. 1: Where the circuitry is interlocked so as to prevent the starting and running of a second motor-compressor or group of motor-compressors, the conductor size shall be determined from the largest motor-compressor or group of motor-compressors that is to be operated at a given time.
Exception No. 2: The branch-circuit conductors for room air conditioners shall be in accordance with Part VII of Article 440
Conductors supplying one or more motor-compressor(s) with or without an additional motor load(s) shall have an ampacity not less than the sum of each of the following:
440.34 Combination Load
Exception: Where the circuitry is interlocked so as to prevent simultaneous operation of the motor-compressor(s) and all other loads connected, the conductor size shall be determined from the largest size required for the motor-compressor(s) and other loads to be operated at a given time.
Conductors supplying a motor-compressor load in addition to other load(s) as calculated from Article 220 and other applicable articles shall have an ampacity sufficient for the other load(s) plus the required ampacity for the motor-compressor load determined in accordance with 440.33 or, for a single motor-compressor, in accordance with 440.32
440.60 General
A room air conditioner that is rated 3-phase or rated over 250 volts shall be directly connected to a wiring method recognized in Chapter 3 , and Part VII shall not apply.
Part VII shall apply to electrically energized room air conditioners that control temperature and humidity. For the purpose of Part VII, a room air conditioner (with or without provisions for heating) shall be considered as an ac appliance of the air-cooled window, console, or in-wall type that is installed in the conditioned room and that incorporates a hermetic refrigerant motor-compressor (s). Part VII covers equipment rated not over 250 volts, single phase, and the equipment shall be permitted to be cord-and attachment-plug -connected.
440.64 Supply Cords
Where a flexible cord is used to supply a room air conditioner, the length of such cord shall not exceed 3.0 m (10 ft) for a nominal, 120-volt rating or 1.8 m (6 ft) for a nominal, 208- or 240-volt rating.
445.1 Scope
This article contains installation and other requirements for generators.
445.6 Listing
Exception: One of a kind or custom manufactured generators shall be permitted to be field labeled by a field evaluation body
Informational Note: For additional information, see UL , Standard for Stationary Engine Generator Assemblies.
Stationary generators 600 volts and less shall be listed.
445.10 Location
Informational Note: See NFPA 37, Standard for the Installation and Use of Stationary Combustion Engines and Gas Turbines, for information on the location of generator exhaust.
Generators shall be of a type suitable for the locations in which they are installed. They shall also meet the requirements for motors in 430.14.
445.11 Marking
Nameplates or manufacturer's instructions shall provide the following information for all stationary generators and portable generators rated more than 15 kW:
Marking shall be provided by the manufacturer to indicate whether or not the generator neutral is bonded to its frame . Where the bonding is modified in the field, additional marking shall be required to indicate whether the neutral is bonded to the frame
Each generator shall be provided with a nameplate giving the manufacturer's name, the rated frequency, the number of phases if ac, the rating in kilowatts or kilovolt-amperes, the power factor, the normal volts and amperes corresponding to the rating, and the rated ambient temperature.
(B) Two-Wire Generators
Two- wire , dc generators shall be permitted to have overcurrent protection in one conductor only if the overcurrent device is actuated by the entire current generated other than the current in the shunt field. The overcurrent device shall not open the shunt field.
(C) 65 Volts or Less
Generators operating at 65 volts or less and driven by individual motors shall be considered as protected by the overcurrent device protecting the motor if these devices will operate when the generators are delivering not more than 150 percent of their full-load rated current.
445.15 Guards for Attendants
Where necessary for the safety of attendants, the requirements of 430.233 shall apply.
445.16 Bushings
Where field-installed wiring passes through an opening in an enclosure , a conduit box, or a barrier, a bushing shall be used to protect the conductors from the edges of an opening having sharp edges. The bushing shall have smooth, well-rounded surfaces where it may be in contact with the conductors. If used where oils, grease, or other contaminants may be present, the bushing shall be made of a material not deleteriously affected.
445.17 Generator Terminal Housings
Exception: This section shall not apply to generators rated over 600 volts.
Generator terminal housings shall comply with 430.12 . Where a horsepower rating is required to determine the required minimum size of the generator terminal housing, the full-load current of the generator shall be compared with comparable motors in Table 430.247 through Table 430.250 . The higher horsepower rating of Table 430.247 and Table 430.250 shall be used whenever the generator selection is between two ratings.
(C) Remote Emergency Shutdown
Generators with greater than 15 kW rating shall be provided with a remote emergency stop switch to shut down the prime mover . The remote emergency stop switch shall be located outside the equipment room or generator enclosure and shall also meet the requirements of 445.18(B) (1) and (B)(2).
450.2 Definition
Transformer. An individual transformer, single-or polyphase,An individual transformer, single-or polyphase, identified by a single nameplate, unless otherwise indicated in this article.
The definitions in this section shall apply only within this article.
(A) Overcurrent Protection
Exception: Where the rated input current of the autotransformer is less than 9 amperes, an overcurrent device rated or set at not more than 167 percent of the input current shall be permitted.
FIGURE 450.4(A) Autotransformer.
Each autotransformer volts, nominal, or less shall be protected by an individual overcurrent device installed in series with each ungrounded input conductor. Such overcurrent device shall be rated or set at not more than 125 percent of the rated full-load input current of the autotransformer. Where this calculation does not correspond to a standard rating of a fuse or nonadjustable circuit breaker and the rated input current is 9 amperes or more, the next higher standard rating described in 240.6 shall be permitted. An overcurrent device shall not be installed in series with the shunt winding (the winding common to both the input and the output circuits) of the autotransformer between Points A and B as shown in Figure 450.4(A).
(1) Connections
The transformer shall be directly connected to the ungrounded phase conductors and shall not be switched or provided with overcurrent protection that is independent of the main switch and common-trip overcurrent protection for the 3-phase, 4- wire system.
(2) Overcurrent Protection
An overcurrent sensing device shall be provided that will cause the main switch or common-trip overcurrent protection referred to in 450.5(A)(1) to open if the load on the autotransformer reaches or exceeds 125 percent of its continuous current per-phase or neutral rating. Delayed tripping for temporary overcurrents sensed at the autotransformer overcurrent device shall be permitted for the purpose of allowing proper operation of branch or feeder protective devices on the 4- wire system.
(3) Transformer Fault Sensing
Informational Note: This can be accomplished by the use of two subtractive-connected donut-type current transformers installed to sense and signal when an unbalance occurs in the line current to the autotransformer of 50 percent or more of rated current.
A fault-sensing system that causes the opening of a main switch or common-trip overcurrent device for the 3-phase, 4- wire system shall be provided to guard against single-phasing or internal faults.
(4) Rating
The autotransformer shall have a continuous neutral-current rating that is not less than the maximum possible neutral unbalanced load current of the 4- wire system.
(1) Rating
The autotransformer shall have a continuous neutral-current rating not less than the specified ground- fault current
450.6 Secondary Ties
As used in this section, the word transformer means a transformer or a bank of transformers operating as a unit.
As used in this article, a secondary tie is a circuit operating at volts, nominal, or less between phases that connects two power sources or power supply points, such as the secondaries of two transformers. The tie shall be permitted to consist of one or more conductors per phase or neutral. Conductors connecting the secondaries of transformers in accordance with 450.7 shall not be considered secondary ties.
(1) Loads at Transformer Supply Points Only
Where all loads are connected at the transformer supply points at each end of the tie and overcurrent protection is not provided in accordance with Parts I, II, and VIII of Article 240 , the ampacity of the tie shall not be less than 67 percent of the rated secondary current of the highest rated transformer supplying the secondary tie system.
(2) Loads Connected Between Transformer Supply Points
Exception: Tie circuits comprised of multiple conductors per phase shall be permitted to be sized and protected in accordance with 450.6(A)(4)
Where load is connected to the tie at any point between transformer supply points and overcurrent protection is not provided in accordance with Parts I, II, and VIII of Article 240 , the ampacity of the tie shall not be less than 100 percent of the rated secondary current of the highest rated transformer supplying the secondary tie system.
(4) Interconnection of Phase Conductors Between Transformer Supply Points
(a) Interconnected. The conductors shall be interconnected in order to establish a load supply point, and the protective device specified in 450.6(A)(3) shall be provided in each ungrounded tie conductor at this point on both sides of the interconnection. The means of interconnection shall have an ampacity not less than the load to be served.
(b) Not Interconnected. The loads shall be connected to one or more individual conductors of a paralleled conductor tie without interconnecting the conductors of each phase or neutral and without the protection specified in 450.6(A)(3) at load connection points. Where this is done, the tie conductors of each phase or neutral shall have a combined capacity ampacity of not less than 133 percent of the rated secondary current of the highest rated transformer supplying the secondary tie system, the total load of such taps shall not exceed the rated secondary current of the highest rated transformer, and the loads shall be equally divided on each phase and on the individual conductors of each phase as far as practicable.
Where the tie consists of more than one conductor per phase or neutral, the conductors of each phase or neutral shall comply with 450.6(A)(4)(a) or (A)(4)(b).
(5) Tie Circuit Control
Where the operating voltage exceeds 150 volts to ground , secondary ties provided with limiters shall have a switch at each end that, when open, de-energizes the associated tie conductors and limiters. The current rating of the switch shall not be less than the rated current ampacity of the conductors connected to the switch. It shall be capable of interrupting its rated current, and it shall be constructed so that it will not open under the magnetic forces resulting from short-circuit current.
(B) Overcurrent Protection for Secondary Connections
Where secondary ties are used, an overcurrent device rated or set at not more than 250 percent of the rated secondary current of the transformers shall be provided in the secondary connections of each transformer supplying the tie system. In addition, an automatic circuit breaker actuated by a reverse-current relay set to open the circuit at not more than the rated secondary current of the transformer shall be provided in the secondary connection of each transformer.
450.7 Parallel Operation
Transformers shall be permitted to be operated in parallel and switched as a unit, provided the overcurrent protection for each transformer meets the requirements of 450.3(A) for primary and secondary protective devices over volts, or 450.3(B) for primary and secondary protective devices volts or less.
(A) Mechanical Protection
Appropriate provisions shall be made to minimize the possibility of damage to transformers from external causes where the transformers are exposed to physical damage.
(B) Case or Enclosure
Dry-type transformers shall be provided with a noncombustible moisture-resistant case or enclosure that provides protection against the accidental insertion of foreign objects.
450.9 Ventilation
Informational Note No. 1: See IEEE C57.12.00-, General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers, and IEEE C57.12.01-, General Requirements for Dry-Type Distribution and Power Transformers.
Informational Note No. 2: Additional losses occur in some transformers where nonsinusoidal currents are present, resulting in increased heat in the transformer above its rating. See IEEE C57.110-, Recommended Practice for Establishing Liquid-Filled and Dry-Type Power and Distribution Transformer Capability When Supplying Nonsinusoidal Load Currents, where transformers are utilized with nonlinear loads
Transformers with ventilating openings shall be installed so that the ventilating openings are not blocked by walls or other obstructions. The required clearances shall be clearly marked on the transformer. Transformer top surfaces that are horizontal and readily accessible shall be marked to prohibit storage.
The ventilation shall dispose of the transformer full-load heat losses without creating a temperature rise that is in excess of the transformer rating.
(A) General
Each transformer shall be provided with a nameplate giving the following information:
(B) Source Marking
A transformer shall be permitted to be supplied at the marked secondary voltage , provided that the installation is in accordance with the manufacturer's instructions.
450.13 Accessibility
All transformers and transformer vaults shall be readily accessible to qualified personnel for inspection and maintenance or shall meet the requirements of 450.13(A) or 450.13(B)
(A) Open Installations
Dry-type transformers volts, nominal, or less, located in the open on walls, columns, or structures, shall not be required to be readily accessible
(B) Hollow Space Installations
Dry-type transformers volts, nominal, or less and not exceeding 50 kVA shall be permitted in hollow spaces of buildings not permanently closed in by structure, provided they meet the ventilation requirements of 450.9 and separation from combustible materials requirements of 450.21(A) . Transformers so installed shall not be required to be readily accessible
450.14 Disconnecting Means
Transformers, other than Class 2 or Class 3 transformers, shall have a disconnecting means located either in sight of the transformer or in a remote location. Where located in a remote location, the disconnecting means shall be lockable open in accordance with 110.25 , and its location shall be field marked on the transformer.
(A) Not Over /2 kVA
1/2 kVA or less shall have a separation of at least 300 mm (12 in.) from combustible material unless separated from the combustible material by a fire-resistant, heat-insulated barrier.Exception: This rule shall not apply to transformers rated for volts, nominal, or less that are completely enclosed , except for ventilating openings.
Dry-type transformers installed indoors and rated 112kVA or less shall have a separation of at least 300 mm (12 in.) from combustible material unless separated from the combustible material by a fire-resistant, heat-insulated barrier.
(B) Over /2 kVA
1/2 kVA rating shall be installed in a transformer room of fire-resistant construction having a minimum fire rating of 1 hour.Exception No. 1: Transformers with Class 155 or higher insulation systems and separated from combustible material by a fire-resistant, heat-insulating barrier or by not less than 1.83 m (6 ft) horizontally and 3.7 m (12 ft) vertically.
Exception No. 2: Transformers with Class 155 or higher insulation systems and completely enclosed except for ventilating openings.
Informational Note: See ASTM E11918a, Standard Test Methods for Fire Tests of Building Construction and Materials.
Individual dry-type transformers of more than 112kVA rating shall be installed in a transformer room of fire-resistant construction having a minimum fire rating of 1 hour.
(C) Over 35,000 Volts
Dry-type transformers rated over 35,000 volts shall be installed in a vault complying with Part III of this article.
450.22 Dry-Type Transformers Installed Outdoors
enclosure. 1/2 kVA shall not be located within 300 mm (12 in.) of combustible materials of buildings unless the transformer has Class 155 insulation systems or higher and is completelyTransformers exceeding 112kVA shall not be located within 300 mm (12 in.) of combustible materials of buildings unless the transformer has Class 155 insulation systems or higher and is completely enclosed except for ventilating openings.
Dry-type transformers installed outdoors shall have a weatherproof
450.23 Less-Flammable Liquid-Insulated Transformers
Transformers insulated with listed less-flammable liquids that have a fire point of not less than 300°C shall be permitted to be installed in accordance with 450.23(A) or 450.23(B)
(A) Indoor Installations
Informational Note: Such restrictions can include, but are not limited to, maximum pressure of the tank, use of a pressure relief valve, appropriate fuse types, and proper sizing of overcurrent protection.
Indoor installations shall be permitted in accordance with one of the following:
(B) Outdoor Installations
Informational Note No. 1: Installations adjacent to combustible material, fire escapes, or door and window openings can require additional safeguards such as those listed in 450.27
Informational Note No. 2: Such restrictions can include, but are not limited to: maximum pressure of the tank, use of a pressure relief valve, appropriate fuse types, and proper sizing of overcurrent protection.
Informational Note No. 1: As used in this section, Type I and Type II buildings refers to Type I and Type II building construction as defined in NFPA 220-, Standard on Types of Building Construction. Combustible materials refers to those materials not classified as noncombustible or limited-combustible as defined in NFPA 220-, Standard on Types of Building Construction.
Informational Note No. 2: See definition of Listed in Article 100
Less-flammable liquid-filled transformers shall be permitted to be installed outdoors, attached to, adjacent to, or on the roof of buildings, if installed in accordance with (1) or (2).
450.24 Nonflammable Fluid-Insulated Transformers
Informational Note: Safety may be increased if fire hazard analyses are performed for such transformer installations.
For the purposes of this section, a nonflammable dielectric fluid is one that does not have a flash point or fire point and is not flammable in air.
Transformers insulated with a dielectric fluid identified as nonflammable shall be permitted to be installed indoors or outdoors. Such transformers installed indoors and rated over 35,000 volts shall be installed in a vault. Such transformers installed indoors shall be furnished with a liquid confinement area and a pressure-relief vent. The transformers shall be furnished with a means for absorbing any gases generated by arcing inside the tank, or the pressure-relief vent shall be connected to a chimney or flue that will carry such gases to an environmentally safe area.
450.25 Askarel-Insulated Transformers Installed Indoors
Askarel -insulated transformers installed indoors and rated over 25 kVA shall be furnished with a pressure-relief vent. Where installed in a poorly ventilated place, they shall be furnished with a means for absorbing any gases generated by arcing inside the case, or the pressure-relief vent shall be connected to a chimney or flue that carries such gases outside the building. Askarel -insulated transformers rated over 35,000 volts shall be installed in a vault.450.26 Oil-Insulated Transformers Installed Indoors
Exception No. 1: Where the total capacity does not exceed /2 kVA, the vault specified in Part III of this article shall be permitted to be constructed of reinforced concrete that is not less than 100 mm (4 in.) thick.
Exception No. 2: Where the nominal voltage does not exceed , a vault shall not be required if suitable arrangements are made to prevent a transformer oil fire from igniting other materials and the total capacity in one location does not exceed 10 kVA in a section of the building classified as combustible or 75 kVA where the surrounding structure is classified as fire-resistant construction.
Exception No. 3: Electric furnace transformers that have a total rating not exceeding 75 kVA shall be permitted to be installed without a vault in a building or room of fire-resistant construction, provided suitable arrangements are made to prevent a transformer oil fire from spreading to other combustible material.
Exception No. 4: A transformer that has a total rating not exceeding 75 kVA and a supply voltage of volts or less that is an integral part of charged-particle-accelerating equipment shall be permitted to be installed without a vault in a building or room of noncombustible or fire-resistant construction, provided suitable arrangements are made to prevent a transformer oil fire from spreading to other combustible material.
Exception No. 5: Transformers shall be permitted to be installed in a detached building that does not comply with Part III of this article if neither the building nor its contents present a fire hazard to any other building or property, and if the building is used only in supplying electric service and the interior is accessible only to qualified persons.
Exception No. 6: Oil-insulated transformers shall be permitted to be used without a vault in portable and mobile surface mining equipment (such as electric excavators) if each of the following conditions is met:
Oil-insulated transformers installed indoors shall be installed in a vault constructed as specified in Part III of this article.
450.27 Oil-Insulated Transformers Installed Outdoors
In cases where the transformer installation presents a fire hazard, one or more of the following safeguards shall be applied according to the degree of hazard involved:
Oil enclosures shall be permitted to consist of fire-resistant dikes, curbed areas or basins, or trenches filled with coarse, crushed stone. Oil enclosures shall be provided with trapped drains where the exposure and the quantity of oil involved are such that removal of oil is important.
Informational Note: For additional information on transformers installed on poles or structures or under ground , see ANSI/IEEE C2, National Electrical Safety Code.
Combustible material, combustible buildings, and parts of buildings, fire escapes, and door and window openings shall be safeguarded from fires originating in oil-insulated transformers installed on roofs, attached to or adjacent to a building or combustible material.
450.28 Modification of Transformers
When modifications are made to a transformer in an existing installation that change the type of the transformer with respect to Part II of this article, such transformer shall be marked to show the type of insulating liquid installed, and the modified transformer installation shall comply with the applicable requirements for that type of transformer.
450.41 Location
Vaults shall be located where they can be ventilated to the outside air without using flues or ducts wherever such an arrangement is practicable.
450.42 Walls, Roofs, and Floors
Exception: Where transformers are protected with automatic sprinkler, water spray, carbon dioxide, or halon, construction of 1-hour rating shall be permitted.
Informational Note No. 1: For additional information, see ASTM E119-18a, Methods for Fire Tests of Building Construction and Materials.
Informational Note No. 2: A typical 3-hour construction is 150 mm (6 in.) thick reinforced concrete.
The walls and roofs of vaults shall be constructed of materials that have approved structural strength for the conditions with a minimum fire resistance of 3 hours. The floors of vaults in contact with the earth shall be of concrete that is not less than 100 mm (4 in.) thick, but, where the vault is constructed with a vacant space or other stories below it, the floor shall have approved structural strength for the load imposed thereon and a minimum fire resistance of 3 hours. For the purposes of this section, studs and wallboard construction shall not be permitted.
450.43 Doorways
Vault doorways shall be protected in accordance with 450.43(A) , (B), and (C).
(A) Type of Door
Exception: Where transformers are protected with automatic sprinkler, water spray, carbon dioxide, or halon, construction of 1-hour rating shall be permitted.
Informational Note: For additional information, see NFPA 80-, Standard for Fire Doors and Other Opening Protectives.
Each doorway leading into a vault from the building interior shall be provided with a tight- fitting door that has a minimum fire rating of 3 hours. The authority having jurisdiction shall be permitted to require such a door for an exterior wall opening where conditions warrant.
(B) Sills
A door sill or curb that is of an approved height that will confine the oil from the largest transformer within the vault shall be provided, and in no case shall the height be less than 100 mm (4 in.).
(C) Locks
Doors shall be equipped with locks, and doors shall be kept locked, with access being allowed only to qualified persons. Personnel doors shall open in the direction of egress and be equipped with listed fire exit hardware.
(A) Location
Ventilation openings shall be located as far as possible from doors, windows, fire escapes, and combustible material.
(B) Arrangement
A vault ventilated by natural circulation of air shall be permitted to have roughly half of the total area of openings required for ventilation in one or more openings near the floor and the remainder in one or more openings in the roof or in the sidewalls near the roof, or all of the area required for ventilation shall be permitted in one or more openings in or near the roof.
(C) Size
2 (3 in.2) per kVA of transformer capacity in 2 (1 ft2) for any capacity under 50 kVA.For a vault ventilated by natural circulation of air to an outdoor area, the combined net area of all ventilating openings, after deducting the area occupied by screens, gratings, or louvers, shall not be less than mm(3 in.) per kVA of transformer capacity in service , and in no case shall the net area be less than 0.1 m(1 ft) for any capacity under 50 kVA.
(D) Covering
Ventilation openings shall be covered with durable gratings, screens, or louvers, according to the treatment required in order to avoid unsafe conditions.
(E) Dampers
1/2 hours.Informational Note: See ANSI/UL 555-, Standard for Fire Dampers.
All ventilation openings to the indoors shall be provided with automatic closing fire dampers that operate in response to a vault fire. Such dampers shall possess a standard fire rating of not less than 1 hours.
(F) Ducts
Ventilating ducts shall be constructed of fire-resistant material.
450.46 Drainage
Where practicable, vaults containing more than 100 kVA transformer capacity shall be provided with a drain or other means that will carry off any accumulation of oil or water in the vault unless local conditions make this impracticable. The floor shall be pitched to the drain where provided.
450.47 Water Pipes and Accessories
Any pipe or duct system foreign to the electrical installation shall not enter or pass through a transformer vault. Piping or other facilities provided for vault fire protection, or for transformer cooling, shall not be considered foreign to the electrical installation.
450.48 Storage in Vaults
Materials shall not be stored in transformer vaults.
455.1 Scope
This article covers the installation and use of phase converters
455.3 Other Articles
Phase converters shall comply with this article and with the applicable provisions of other articles of this Code.455.4 Marking
Each phase converter shall be provided with a permanent nameplate indicating the following:
(A) Ampacity
Informational Note: Single-phase conductors sized to prevent a voltage drop not exceeding 3 percent from the source of supply to the phase converter may help ensure proper starting and operation of motor loads.
The ampacity of the single-phase supply conductors shall be determined by 455.6(A)(1) or (A)(2).
(1) Variable Loads
Where the loads to be supplied are variable, the conductor ampacity shall not be less than 125 percent of the phase converter nameplate single-phase input full-load amperes.
(A) Variable Loads
Where the loads to be supplied are variable, overcurrent protection shall be set at not more than 125 percent of the phase converter nameplate single-phase input full-load amperes.
(B) Type
The disconnecting means shall be a switch rated in horsepower, a circuit breaker , or a molded-case switch. Where only nonmotor loads are served, an ampere-rated switch shall be permitted.
(C) Rating
The ampere rating of the disconnecting means shall not be less than 115 percent of the rated maximum single-phase input full-load amperes or, for specific fixed loads, shall be permitted to be selected from 455.8(C)(1) or (C)(2).
(1) Current Rated Disconnect
The disconnecting means shall be a circuit breaker or molded-case switch with an ampere rating not less than 250 percent of the sum of the following:
(2) Horsepower Rated Disconnect
The disconnecting means shall be a switch with a horsepower rating. The equivalent locked rotor current of the horsepower rating of the switch shall not be less than 200 percent of the sum of the following:
455.23 Capacitors
Capacitors that are not an integral part of the rotary-phase conversion system but are installed for a motor load shall be connected to the line side of that motor overload protective device
460.1 Scope
Surge capacitors or capacitors included as a component part of other apparatus and conforming with the requirements of such apparatus are excluded from these requirements.
This article also covers the installation of capacitors in hazardous (classified) locations as modified by Articles 501 through 503
This article covers the installation of capacitors on electrical circuits.
460.2 Definitions
Safe Zone. Low probability of damage other than a slight swelling of the capacitor case, asLow probability of damage other than a slight swelling of the capacitor case, as identified by the case rupture curve of the capacitor.
The definition in this section shall apply only within this article.
(B) Accidental Contact
Where capacitors are accessible to unauthorized and unqualified persons, they shall be enclosed , located, or guarded so that persons cannot come into accidental contact or bring conducting materials into accidental contact with exposed energized parts, terminals , or buses associated with them. However, no additional guarding is required for enclosures accessible only to authorized and qualified persons.
460.6 Discharge of Stored Energy
Capacitors shall be provided with a means of discharging stored energy.
(A) Time of Discharge
The residual voltage of a capacitor shall be reduced to 50 volts, nominal, or less within 1 minute after the capacitor is disconnected from the source of supply.
(B) Means of Discharge
The discharge circuit shall be either permanently connected to the terminals of the capacitor or capacitor bank or provided with automatic means of connecting it to the terminals of the capacitor bank on removal of voltage from the line. Manual means of switching or connecting the discharge circuit shall not be used.
(A) Ampacity
The ampacity of capacitor circuit conductors shall not be less than 135 percent of the rated current of the capacitor. The ampacity of conductors that connect a capacitor to the terminals of a motor or to motor circuit conductors shall not be less than one-third the ampacity of the motor circuit conductors and in no case less than 135 percent of the rated current of the capacitor.
460.12 Marking
Each capacitor shall be provided with a nameplate giving the name of the manufacturer, rated voltage , frequency, kilovar or amperes, number of phases, and, if filled with a combustible liquid, the volume of liquid. Where filled with a nonflammable liquid, the nameplate shall so state. The nameplate shall also indicate whether a capacitor has a discharge device inside the case.
(A) Load Current
Group-operated switches shall be used for capacitor switching and shall be capable of the following:
(1) General
A means shall be installed to isolate from all sources of voltage each capacitor, capacitor bank, or capacitor installation that will be removed from service as a unit. The isolating means shall provide a visible gap in the electrical circuit adequate for the operating voltage
(C) Additional Requirements for Series Capacitors
The proper switching sequence shall be ensured by use of one of the following:
(C) Protected Individually or in Groups
Capacitors shall be permitted to be protected individually or in groups.
460.26 Identification
Each capacitor shall be provided with a permanent nameplate giving the manufacturer's name, rated voltage , frequency, kilovar or amperes, number of phases, and the volume of liquid identified as flammable, if such is the case.
(A) Means to Reduce the Residual Voltage
A means shall be provided to reduce the residual voltage of a capacitor to 50 volts or less within 5 minutes after the capacitor is disconnected from the source of supply.
(B) Connection to Terminals
A discharge circuit shall be either permanently connected to the terminals of the capacitor or provided with automatic means of connecting it to the terminals of the capacitor bank after disconnection of the capacitor from the source of supply. The windings of motors, transformers, or other equipment directly connected to capacitors without a switch or overcurrent device interposed shall meet the requirements of 460.28(A)
470.1 Scope
Exception: Resistors and reactors that are component parts of other apparatus.
This article also covers the installation of resistors and reactors in hazardous (classified) locations as modified by Articles 501 through 504
This article covers the installation of separate resistors and reactors on electrical circuits.
470.2 Location
Resistors and reactors shall not be placed where exposed to physical damage.
470.3 Space Separation
A thermal barrier shall be required if the space between the resistors and reactors and any combustible material is less than 305 mm (12 in.).
(A) Protected Against Physical Damage
Resistors and reactors shall be protected against physical damage.
(C) Combustible Materials
Resistors and reactors shall not be installed in close enough proximity to combustible materials to constitute a fire hazard and shall have a clearance of not less than 305 mm (12 in.) from combustible materials.
(D) Clearances
Clearances from resistors and reactors to grounded surfaces shall be adequate for the voltage involved.
(E) Temperature Rise From Induced Circulating Currents
Metallic enclosures of reactors and adjacent metal parts shall be installed so that the temperature rise from induced circulating currents is not hazardous to personnel or does not constitute a fire hazard.
470.20 Oil-Filled Reactors
Installation of oil-filled reactors, in addition to the above requirements, shall comply with applicable requirements of Article 450
480.1 Scope
Informational Note: The following standards are frequently referenced for the installation of stationary batteries:
This article applies to all stationary installations of storage batteries
(A) Corrosion Prevention
Informational Note: The battery manufacturer's installation and instruction manual can be used for guidance for acceptable materials.
Where mating dissimilar metals, antioxidant material suitable for the battery connection shall be used where recommended by the battery manufacturer.
(C) Battery Terminals
Informational Note: Conductors are commonly pre-formed to eliminate stress on battery terminations. Fine stranded cables may also eliminate the stress on battery terminations. See the manufacturer's instructions for guidance.
Electrical connections to the battery, and the cable (s) between cells on separate levels or racks, shall not put mechanical strain on the battery terminals Terminal plates shall be used where practicable.
(C) Disconnection of Series Battery Circuits
Battery circuits exceeding 240 volts dc nominal between conductors or to ground and subject to field servicing shall have provisions to disconnect the series-connected strings into segments not exceeding 240 volts dc nominal for maintenance by qualified persons. Non-load-break bolted or plug-in disconnects shall be permitted.
(E) Busway
Where a dc busway system is installed, the disconnecting means shall be permitted to be incorporated into the busway.
480.9 Battery Support Systems
For battery chemistries with corrosive electrolyte , the structure that supports the battery shall be resistant to deteriorating action by the electrolyte . Metallic structures shall be provided with nonconducting support members for the cells , or shall be constructed with a continuous insulating material. Paint alone shall not be considered as an insulating material.
(A) Ventilation
Informational Note No. 1: See NFPA 1 -, Fire Code, Chapter 52, for ventilation considerations for specific battery chemistries.
Informational Note No. 2: Some battery technologies do not require ventilation.
Informational Note No. 3: For additional information on the ventilation of stationary battery systems , see IEEE Std -/ASHRAE Guideline 21- Guide for the Ventilation and Thermal Management of Batteries for Stationary Applications.
Provisions appropriate to the battery technology shall be made for sufficient diffusion and ventilation of gases from the battery, if present, to prevent the accumulation of an explosive mixture.
(D) Top Terminal Batteries
Informational Note: IEEE -, IEEE Recommended Practice for Installation Design and Installation of Valve-Regulated Lead-Acid Batteries for Stationary Applications, provides guidance for top clearance of valve-regulated lead-acid batteries, which are commonly used in battery cabinets
Where top terminal batteries are installed on tiered racks or on shelves of battery cabinets , working space in accordance with the battery manufacturer's instructions shall be provided between the highest point on a cell and the row, shelf, or ceiling above that point.
(E) Egress
Personnel doors intended for entrance to, and egress from, rooms designated as battery rooms shall open in the direction of egress and shall be equipped with listed panic or listed fire exit hardware.
(F) Piping in Battery Rooms
Gas piping shall not be permitted in dedicated battery rooms.
(A) Vented Cells
Informational Note: A flame arrester prevents destruction of the cell due to ignition of gases within the cell by an external spark or flame.
Each vented cell shall be equipped with a flame arrester.
(B) Sealed Cells
Where the battery is constructed such that an excessive accumulation of pressure could occur within the cell during operation, a pressure-release vent shall be provided.
490.1 Scope
Informational Note No. 1: See NFPA 70E-, Standard for Electrical Safety in the Workplace, for electrical safety requirements for employee workplaces.
Informational Note No. 2: For further information on hazard signs and labels, see ANSI Z535.4-, Product Signs and Safety Labels.
Informational Note No. 3: For information regarding power distribution apparatus, see IEEE .5-, Recommended Practice for the Application of Power Distribution Apparatus in Industrial and Commercial Power Systems.
This article covers the general requirements for equipment operating at more than volts, nominal.
490.2 Definition
High Voltage. A potential difference of more than volts, nominal.A potential difference of more than volts, nominal.
The definition in this section shall apply only within this article.
(2) Operating Characteristics
(5) Retrofit Trip Units
Retrofit trip units shall be listed for use with the specific circuit breaker with which it is installed.
(1) Use
Where fuses are used to protect conductors and equipment , a fuse shall be placed in each ungrounded conductor. Two power fuses shall be permitted to be used in parallel to protect the same load if both fuses have identical ratings and both fuses are installed in an identified common mounting with electrical connections that divide the current equally. Power fuses of the vented type shall not be used indoors, underground, or in metal enclosures unless identified for the use.
(5) Fuses
Fuses that expel flame in opening the circuit shall be designed or arranged so that they function properly without hazard to persons or property.(6) Fuseholders
DANGER DISCONNECT CIRCUIT BEFORE REPLACING FUSES
Exception: Fuses and fuseholders designed to permit fuse replacement by qualified persons using identified equipment without de-energizing the fuseholder shall be permitted.
Fuseholders shall be designed or installed so that they are de- energized while a fuse is being replaced. A field-applied permanent and legible sign, in accordance with 110.21(B) , shall be installed immediately adjacent to the fuseholders and shall be worded as follows:
(1) Installation
Cutouts shall be located so that they may be readily and safely operated and re-fused, and so that the exhaust of the fuses does not endanger persons. Distribution cutouts shall not be used indoors, underground, or in metal enclosures
(2) Operation
Where fused cutouts are not suitable to interrupt the circuit manually while carrying full load, an approved means shall be installed to interrupt the entire load. Unless the fused cutouts are interlocked with the switch to prevent opening of the cutouts under load, a conspicuous sign shall be placed at such cutouts identifying that they shall not be operated under load.
(4) Voltage Rating
The maximum voltage rating of cutouts shall not be less than the maximum circuit voltage
(5) Identification
Distribution cutouts shall have on their body, door, or fuse tube a permanent and legible nameplate or identification showing the manufacturer's type or designation, continuous current rating, maximum voltage rating, and interrupting rating
(6) Fuse Links
Fuse links shall have a permanent and legible identification showing continuous current rating and type.(7) Structure Mounted Outdoors
The height of cutouts mounted outdoors on structures shall provide safe clearance between lowest energized parts (open or closed position) and standing surfaces, in accordance with 110.34(E)
(1) Continuous Current Rating
The continuous current rating of oil-filled cutouts shall not be less than the maximum continuous current through the cutout.
(3) Voltage Rating
The maximum voltage rating of oil-filled cutouts shall not be less than the maximum circuit voltage
(4) Fault Closing Rating
Oil-filled cutouts shall have a fault closing rating not less than the maximum asymmetrical fault current that can occur at the cutout location, unless suitable interlocks or operating procedures preclude the possibility of closing into a fault.
(5) Identification
Oil-filled cutouts shall have a permanent and legible nameplate showing the rated continuous current, rated maximum voltage , and rated interrupting current.
(6) Fuse Links
Fuse links shall have a permanent and legible identification showing the rated continuous current.(7) Location
Cutouts shall be located so that they are readily and safely accessible for re-fusing, with the top of the cutout not over 1.5 m (5 ft) above the floor or platform.
(8) Enclosure
Suitable barriers or enclosures shall be provided to prevent contact with nonshielded cables or energized parts of oil-filled cutouts.
(E) Load Interrupters
Where more than one switch is installed with interconnected load terminals to provide for alternate connection to different supply conductors, each switch shall be provided with a warning sign identifying the presence of more than one source. Each warning sign or label shall comply with 110.21
Load-interrupter switches shall be permitted if suitable fuses or circuit breakers are used in conjunction with these devices to interrupt available fault currents . Where these devices are used in combination, they shall be coordinated electrically so that they will safely withstand the effects of closing, carrying, or interrupting all possible currents up to the assigned maximum short-circuit rating.
(1) Continuous Current Rating
The continuous current rating of interrupter switches shall equal or exceed the maximum continuous current at the point of installation.
(2) Voltage Rating
The maximum voltage rating of interrupter switches shall equal or exceed the maximum circuit voltage
(3) Identification
Interrupter switches shall have a permanent and legible nameplate including the following information: manufacturer's type or designation, continuous current rating, interrupting current rating, fault closing rating, maximum voltage rating.
(4) Switching of Conductors
The switching mechanism shall be arranged to be operated from a location where the operator is not exposed to energized parts and shall be arranged to open all ungrounded conductors of the circuit simultaneously with one operation. Switches shall be arranged to be locked in the open position. Metal- enclosed switches shall be operable from outside the enclosure
(5) Stored Energy for Opening
The stored-energy operator shall be permitted to be left in the uncharged position after the switch has been closed if a single movement of the operating handle charges the operator and opens the switch.
(6) Supply Terminals
The supply terminals of fused interrupter switches shall be installed at the top of the switch enclosure , or, if the terminals are located elsewhere, the equipment shall have barriers installed so as to prevent persons from accidentally contacting energized parts or dropping tools or fuses into energized parts.
490.23 Voltage Regulators
Proper switching sequence for regulators shall be ensured by use of one of the following:
490.24 Minimum Space Separation
Table 490.24 Minimum Clearance of Live Parts Nominal Voltage Rating (kV) Impulse Withstand, Basic Impulse Level B.I.L (kV) Minimum Clearance of Live Parts Phase-to-Phase Phase-to-Ground Indoors Outdoors Indoors Outdoors Indoors Outdoors mm in. mm in. mm in. mm in. 2.44.16 60 95 115 4.5 180 7 80 3.0 155 6 7.2 75 95 140 5.5 180 7 105 4.0 155 6 13.8 95 110 195 7.5 305 12 130 5.0 180 7 14.4 110 110 230 9.0 305 12 170 6.5 180 7 23 125 150 270 10.5 385 15 190 7.5 255 10 34.5 150 150 320 12.5 385 15 245 9.5 255 10 200 200 460 18.0 460 18 335 13.0 335 13 46 200 460 18 335 13 250 535 21 435 17 69 250 535 21 435 17 350 790 31 635 25 115 550 53 42 138 550 53 42 650 63 50 161 650 63 50 750 72 58 230 750 72 58 900 89 71 105 83 Note: The values given are the minimum clearance for rigid parts and bare conductors under favorable service conditions. They shall be increased for conductor movement or under unfavorable service conditions or wherever space limitations permit. The selection of the associated impulse withstand voltage for a particular system voltage is determined by the characteristics of the surge protective equipment.In field-fabricated installations, the minimum air separation between bare live conductors and between such conductors and adjacent grounded surfaces shall not be less than the values given in Table 490.24. These values shall not apply to interior portions or exterior terminals of equipment designed, manufactured, and tested in accordance with accepted national standards.
490.25 Backfeed
Installations where the possibility of backfeed exists shall comply with 490.25(A) and (B), which follow.
(B) Diagram
A permanent and legible single-line diagram of the local switching arrangement, clearly identifying each point of connection to the high- voltage section, shall be provided within sight of each point of connection.
490.30 General
Part III covers assemblies of switchgear and industrial control equipment including, but not limited to, switches and interrupting devices and their control , metering, protection, and regulating equipment where they are an integral part of the assembly, with associated interconnections and supporting structures.
490.31 Arrangement of Devices in Assemblies
Arrangement of devices in assemblies shall be such that individual components can safely perform their intended function without adversely affecting the safe operation of other components in the assembly.
490.38 Door Stops and Cover Plates
2 (12 ft2) in area or 27 kg (60 lb) in weight, unless they are hinged and bolted or locked.External hinged doors or covers shall be provided with stops to hold them in the open position. Cover plates intended to be removed for inspection of energized parts or wiring shall be equipped with lifting handles and shall not exceed 1.1 m(12 ft) in area or 27 kg (60 lb) in weight, unless they are hinged and bolted or locked.
490.39 Gas Discharge From Interrupting Devices
Gas discharged during operating of interrupting devices shall be directed so as not to endanger personnel.
490.40 Visual Inspection Windows
Windows intended for visual inspection of disconnecting switches or other devices shall be of suitable transparent material.
490.42 Interlocks Interrupter Switches
Interrupter switches equipped with stored energy mechanisms shall have mechanical interlocks to prevent access to the switch compartment unless the stored energy mechanism is in the discharged or blocked position.
490.43 Stored Energy for Opening
The stored energy operator shall be permitted to be left in the uncharged position after the switch has been closed if a single movement of the operating handle charges the operator and opens the switch.
(A) Supply Terminals
The supply terminals of fused interrupter switches shall be installed at the top of the switch enclosure or, if the terminals are located elsewhere, the equipment shall have barriers installed so as to prevent persons from accidentally contacting energized parts or dropping tools or fuses into energized parts.
(B) Backfeed
Where fuses can be energized by backfeed, a sign shall be placed on the enclosure door identifying this hazard.
(C) Switching Mechanism
The switching mechanism shall be arranged to be operated from a location outside the enclosure where the operator is not exposed to energized parts and shall be arranged to open all ungrounded conductors of the circuit simultaneously with one operation. Switches shall be lockable open in accordance with 110.25
(A) Circuit Breakers
Circuit breakers equipped with stored energy mechanisms shall be designed to prevent the release of the stored energy unless the mechanism has been fully charged.(B) Mechanical Interlocks
Mechanical interlocks shall be provided in the housing to prevent the complete withdrawal of the circuit breaker from the housing when the stored energy mechanism is in the fully charged position, unless a suitable device is provided to block the closing function of the circuit breaker before complete withdrawal.
490.46 Circuit Breaker Locking
Circuit breakers shall be capable of being locked in the open position or, if they are installed in a drawout mechanism, that mechanism shall be capable of being locked in such a position that the mechanism cannot be moved into the connected position. In either case, the provision for locking shall be lockable open in accordance with 110.25(B) Diagram
Exception: Where the equipment consists solely of a single cubicle or metal- enclosed substation containing only one high- voltage switching device , diagrams shall not be required.
A permanent, single-line diagram of the switchgear shall be provided in a readily visible location within the same room or enclosed area with the switchgear , and this diagram shall clearly identify interlocks, isolation means, and all possible sources of voltage to the installation under normal or emergency conditions, and the marking on the switchgear shall cross-reference the diagram.
(B) Other Requirements
The requirements of this part shall be additional to, or amendatory of, those prescribed in Articles 100 through 725 of this Code. Special attention shall be paid to Article 250
490.52 Overcurrent Protection
Motors driving single or multiple dc generators supplying a system operating on a cyclic load basis do not require overload protection, provided that the thermal rating of the ac drive motor cannot be exceeded under any operating condition. The branch-circuit protective device (s) shall provide short-circuit and locked-rotor protection and shall be permitted to be external to the equipment
490.54 Collector Rings
The collector ring assemblies on revolving-type machines (shovels, draglines, etc.) shall be guarded to prevent accidental contact with energized parts by personnel on or off the machine.
490.70 General
The provisions of Part V shall apply to boilers operating over volts, nominal, in which heat is generated by the passage of current between electrodes through the liquid being heated.
(A) Rating
Each boiler shall be supplied from an individual branch circuit rated not less than 100 percent of the total load.
(B) Common-Trip Fault-Interrupting Device
The circuit shall be protected by a 3-phase, common-trip fault-interrupting device , which shall be permitted to automatically reclose the circuit upon removal of an overload condition but shall not reclose after a fault condition.
(C) Phase-Fault Protection
Phase-fault protection shall be provided in each phase, consisting of a separate phase- overcurrent relay connected to a separate current transformer in the phase.
(D) Ground Current Detection
1/2 percent of the boiler full-load current for 10 seconds or exceeds an instantaneous value of 25 percent of the boiler full-load current.Means shall be provided for detection of the sum of the neutral conductor and equipment grounding conductor currents and shall trip the circuit-interrupting device if the sum of those currents exceeds the greater of 5 amperes or 7percent of the boiler full-load current for 10 seconds or exceeds an instantaneous value of 25 percent of the boiler full-load current.
490.73 Pressure and Temperature Limit Control
Each boiler shall be equipped with a means to limit the maximum temperature, pressure, or both, by directly or indirectly interrupting all current flow through the electrodes. Such means shall be in addition to the temperature, pressure, or both, regulating systems and pressure relief or safety valves.
If you want to learn more, please visit our website Type W Portable Power Cables.