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Chapter 4 Equipment for General Use
480.7(G)(1)
Plaques or directories shall be installed in accordance with 705.10. Exception: This requirement does not apply where a disconnect in 480.7(A) is not required. [480.7(G)(1)](https://2023.antflix.net#480.7(G)(1))
https://2023.antflix.net#480.7(G)(1)
Chapter 4 Equipment for General Use
480.7(G)(2)
A permanent plaque or directory shall be installed in accordance with 710.10. [480.7(G)(2)](https://2023.antflix.net#480.7(G)(2))
https://2023.antflix.net#480.7(G)(2)
Chapter 4 Equipment for General Use
480.8
Batteries constructed of an electrically conductive container shall have insulating support if a voltage is present between the container and ground. [480.8](https://2023.antflix.net#480.8)
https://2023.antflix.net#480.8
Chapter 4 Equipment for General Use
480.9
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 sh...
https://2023.antflix.net#480.9
Chapter 4 Equipment for General Use
480.10
Battery locations shall conform to 480.10(A) through (G). [480.10](https://2023.antflix.net#480.10)
https://2023.antflix.net#480.10
Chapter 4 Equipment for General Use
480.10(A)
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. Informational Note No. 1: See NFPA 1-2021, Fire Code, Chapter 52, for ventilation considerations for specific battery chemis...
https://2023.antflix.net#480.10(A)
Chapter 4 Equipment for General Use
480.10(B)
Guarding of live parts shall comply with 110.27. [480.10(B)](https://2023.antflix.net#480.10(B))
https://2023.antflix.net#480.10(B)
Chapter 4 Equipment for General Use
480.10(C)
Spaces about stationary standby batteries shall comply with 110.26 and 110.34. Working space shall be measured from the edge of the battery cabinet, racks, or trays. For battery racks, there shall be a minimum clearance of 25 mm (1 in.) between a cell container and any wall or structure on the side not requiring access...
https://2023.antflix.net#480.10(C)
Chapter 4 Equipment for General Use
480.10(D)
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. Informational Note: See IEEE 1187-2013, IEEE Recom...
https://2023.antflix.net#480.10(D)
Chapter 4 Equipment for General Use
480.10(E)
Personnel doors intended for entrance to, and egress from, rooms designated as battery rooms shall open at least 90 degrees in the direction of egress and shall be equipped with listed panic or listed fire exit hardware. [480.10(E)](https://2023.antflix.net#480.10(E))
https://2023.antflix.net#480.10(E)
Chapter 4 Equipment for General Use
480.10(F)
Gas piping shall not be permitted in dedicated battery rooms. [480.10(F)](https://2023.antflix.net#480.10(F))
https://2023.antflix.net#480.10(F)
Chapter 4 Equipment for General Use
480.10(G)
Illumination shall be provided for working spaces containing stationary standby batteries. The lighting outlets shall not be controlled by automatic means only. Additional lighting outlets shall not be required where the work space is illuminated by an adjacent light source. The location of luminaires shall not result ...
https://2023.antflix.net#480.10(G)
Chapter 4 Equipment for General Use
480.11(A)
Each vented cell shall be equipped with a flame arrester. Informational Note: A flame arrester prevents destruction of the cell due to ignition of gases within the cell by an external spark or flame. [480.11(A)](https://2023.antflix.net#480.11(A))
https://2023.antflix.net#480.11(A)
Chapter 4 Equipment for General Use
480.11(B)
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. [480.11(B)](https://2023.antflix.net#480.11(B))
https://2023.antflix.net#480.11(B)
Chapter 4 Equipment for General Use
480.12
Flexible cables, as identified in Table 400.4, in sizes 2/0 AWG and larger shall be permitted within the battery enclosure from battery terminals to a nearby junction box where they shall be connected to an approved wiring method. Flexible battery cables shall also be permitted between batteries and cells within the ba...
https://2023.antflix.net#480.12
Chapter 4 Equipment for General Use
480.13
Battery circuits exceeding 100 volts between the conductors or to ground shall be permitted to operate with ungrounded conductors, provided a ground-fault detector and indicator is installed to monitor for ground faults. [480.13](https://2023.antflix.net#480.13)
https://2023.antflix.net#480.13
Chapter 4 Equipment for General Use
495.1
This article covers the general requirements for equipment operating at more than 1000 volts ac, 1500 volts dc, nominal. Informational Note No. 1: See NFPA 70E-2021, Standard for Electrical Safety in the Workplace, for electrical safety requirements for employee workplaces. Informational Note No. 2: See ANSI Z535.4-201...
https://2023.antflix.net#495.1
Chapter 4 Equipment for General Use
495.2
Except as modified within this article, reconditioned equipment shall not be permitted. [495.2](https://2023.antflix.net#495.2)
https://2023.antflix.net#495.2
Chapter 4 Equipment for General Use
495.3(A)
Installation of electrical equipment containing more than 38 L (10 gal) of flammable oil per unit shall meet the requirements of Parts II and III of Article 450. [495.3(A)](https://2023.antflix.net#495.3(A))
https://2023.antflix.net#495.3(A)
Chapter 4 Equipment for General Use
495.3(B)
Enclosures in damp or wet locations shall meet the requirements of 312.2. [495.3(B)](https://2023.antflix.net#495.3(B))
https://2023.antflix.net#495.3(B)
Chapter 4 Equipment for General Use
495.22
Means shall be provided to completely isolate an item of equipment from all ungrounded conductors. The use of isolating switches shall not be required where there are other ways of de-energizing the equipment for inspection and repairs, such as draw-out-type switchgear units and removable truck panels. Isolating switch...
https://2023.antflix.net#495.22
Chapter 4 Equipment for General Use
495.23
Proper switching sequence for regulators shall be ensured by use of one of the following: Mechanically sequenced regulator bypass switch(es)Mechanical interlocksSwitching procedure prominently displayed at the switching location [495.23](https://2023.antflix.net#495.23)
https://2023.antflix.net#495.23
Chapter 4 Equipment for General Use
495.24
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 495.24. These values shall not apply to interior portions or exterior terminals of equipment designed, manufactured, and ...
https://2023.antflix.net#495.24
Chapter 4 Equipment for General Use
495.25
Installations where the possibility of back-feed exists shall comply with 495.25(A) and (B). [495.25](https://2023.antflix.net#495.25)
https://2023.antflix.net#495.25
Chapter 4 Equipment for General Use
495.25(A)
A permanent sign in accordance with 110.21(B) shall be installed on the disconnecting means enclosure or immediately adjacent to open disconnecting means with the following words or equivalent: DANGER - CONTACTS ON EITHER SIDE OF THIS DEVICE MAY BE ENERGIZED BY BACKFEED. [495.25(A)](https://2023.antflix.net#495.25(A))
https://2023.antflix.net#495.25(A)
Chapter 4 Equipment for General Use
495.25(B)
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. [495.25(B)](https://2023.antflix.net#495.25(B))
https://2023.antflix.net#495.25(B)
Chapter 4 Equipment for General Use
495.30
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. [495....
https://2023.antflix.net#495.30
Chapter 4 Equipment for General Use
495.31
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. [495.31](https://2023.antflix.net#495.31)
https://2023.antflix.net#495.31
Chapter 4 Equipment for General Use
495.32
Where access for other than visual inspection is required to a compartment that contains energized high-voltage parts, barriers shall be provided to prevent accidental contact by persons, tools, or other equipment with energized parts. Exposed live parts shall only be permitted in compartments accessible to qualified p...
https://2023.antflix.net#495.32
Chapter 4 Equipment for General Use
495.33
Energized bare parts mounted on doors shall be guarded where the door must be opened for maintenance of equipment or removal of draw-out equipment. [495.33](https://2023.antflix.net#495.33)
https://2023.antflix.net#495.33
Chapter 4 Equipment for General Use
495.34
The unobstructed space opposite terminals or opposite race-ways or cables entering a switchgear or control assembly shall be approved for the type of conductor and method of termination. [495.34](https://2023.antflix.net#495.34)
https://2023.antflix.net#495.34
Chapter 4 Equipment for General Use
495.35(A)
Doors that would provide unqualified persons access to high-voltage energized parts shall be locked. Permanent signs in accordance with 110.21(B) shall be installed on panels or doors that provide access to live parts over 1000 volts and shall read DANGER - HIGH VOLTAGE - KEEP OUT. [495.35(A)](https://2023.antflix.net#...
https://2023.antflix.net#495.35(A)
Chapter 4 Equipment for General Use
495.35(B)
Where operating at 1000 volts, nominal, or less, control equipment, relays, motors, and the like shall not be installed in compartments with high-voltage parts or high-voltage wiring, unless both of the following apply: The access means is interlocked with the high-voltage switch or disconnecting means to prevent the a...
https://2023.antflix.net#495.35(B)
Chapter 4 Equipment for General Use
495.35(C)
High-voltage instrument or control transformers and space heaters shall be permitted to be installed in the high-voltage compartment without access restrictions beyond those that apply to the high-voltage compartment generally. [495.35(C)](https://2023.antflix.net#495.35(C))
https://2023.antflix.net#495.35(C)
Chapter 4 Equipment for General Use
495.37
The metal cases or frames, or both, such as those of instruments, relays, meters, and instrument and control transformers, located in or on switchgear or control assemblies, and the frames of switchgear and control assemblies shall be connected to an equipment grounding conductor or, where permitted, the grounded condu...
https://2023.antflix.net#495.37
Chapter 4 Equipment for General Use
495.38
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 nr (12 ft2) in area or 27 kg (60 lb) in weight, unless they are hinged and bolte...
https://2023.antflix.net#495.38
Chapter 4 Equipment for General Use
495.39
Gas discharged during operating of interrupting devices shall be directed so as not to endanger personnel. [495.39](https://2023.antflix.net#495.39)
https://2023.antflix.net#495.39
Chapter 4 Equipment for General Use
495.40
Windows intended for visual inspection of disconnecting switches or other devices shall be of suitable transparent material. [495.40](https://2023.antflix.net#495.40)
https://2023.antflix.net#495.40
Chapter 4 Equipment for General Use
495.41
Routinely operated industrial control equipment shall meet the requirements of 495.41 (A) unless infrequently operated, as covered in 495.41 (B). [495.41](https://2023.antflix.net#495.41)
https://2023.antflix.net#495.41
Chapter 4 Equipment for General Use
495.41(A)
Control and instrument transfer switch handles or push buttons shall be in a readily accessible location at an elevation of not over 2.0 m (6 ft 7 in.). Exception: Operating handles requiring more than 23 kg (50 lb) of force shall be located no higher than 1.7 m (66 in.) in either the open or closed position. [495.41(A...
https://2023.antflix.net#495.41(A)
Chapter 4 Equipment for General Use
495.41(B)
Where operating handles for such devices as draw-out fuses, fused potential or control transformers and their primary disconnects, and bus transfer and isolating switches are only operated infrequently, the handles shall be permitted to be located where they are safely operable and serviceable from a portable platform....
https://2023.antflix.net#495.41(B)
Chapter 4 Equipment for General Use
495.42
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. [495.42](https://2023.antflix.net#495.42)
https://2023.antflix.net#495.42
Chapter 4 Equipment for General Use
495.43
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. [495.43](https://2023.antflix.net#495.43)
https://2023.antflix.net#495.43
Chapter 4 Equipment for General Use
495.44(A)
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 to prevent persons from accidentally contacting energized parts or dropping tools or fuses into energized parts. [495.44(A)](ht...
https://2023.antflix.net#495.44(A)
Chapter 4 Equipment for General Use
495.44(B)
Where fuses can be energized by backfeed, a sign shall be placed on the enclosure door identifying this hazard. [495.44(B)](https://2023.antflix.net#495.44(B))
https://2023.antflix.net#495.44(B)
Chapter 4 Equipment for General Use
495.44(C)
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. [495.44...
https://2023.antflix.net#495.44(C)
Chapter 4 Equipment for General Use
495.45(A)
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. [495.45(A)](https://2023.antflix.net#495.45(A))
https://2023.antflix.net#495.45(A)
Chapter 4 Equipment for General Use
495.45(B)
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. [495....
https://2023.antflix.net#495.45(B)
Chapter 4 Equipment for General Use
495.46
Circuit breakers shall be capable of being locked in the open position or, if they are installed in a draw-out 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...
https://2023.antflix.net#495.46
Chapter 4 Equipment for General Use
495.47
Switchgear installed as high-voltage service equipment shall include a ground bus for the connection of service cable shields and to facilitate the attachment of safety grounds for personnel protection. This bus shall be extended into the compartment where the service conductors are terminated. Where the compartment do...
https://2023.antflix.net#495.47
Chapter 4 Equipment for General Use
495.48(A)
Substations shall be designed by a qualified licensed professional engineer. Where components or the entirety of the substation is listed by a qualified electrical testing laboratory, documentation of internal design features subject to the listing investigation shall not be required. The design shall address but not b...
https://2023.antflix.net#495.48(A)
Chapter 4 Equipment for General Use
495.48(B)
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 shall clearly identify the following: InterlocksIsolation meansAll possible sources of voltage to the installation under normal or emergency conditionsThe mark...
https://2023.antflix.net#495.48(B)
Chapter 4 Equipment for General Use
495.49
Reconditioned switchgear, or sections of switchgear, shall be permitted. 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. [495.49](https://2023.antflix.net#495.49)
https://2023.antflix.net#495.49
Chapter 4 Equipment for General Use
495.61(A)
The provisions of this part shall apply to installations and use of high-voltage power distribution and utilization equipment that is portable, mobile, or both, and include but not be limited to the following: Substations and switch houses mounted on skidsTrailers or carsMobile shovelsDraglinesCranesHoistsDrillsDredges...
https://2023.antflix.net#495.61(A)
Chapter 4 Equipment for General Use
495.61(B)
Grounding and bonding shall be in accordance with Part X of Article 250. [495.61(B)](https://2023.antflix.net#495.61(B))
https://2023.antflix.net#495.61(B)
Chapter 4 Equipment for General Use
495.61(C)
Approved enclosures or guarding, or both, shall be provided to protect portable and mobile equipment from physical damage. [495.61(C)](https://2023.antflix.net#495.61(C))
https://2023.antflix.net#495.61(C)
Chapter 4 Equipment for General Use
495.61(D)
Disconnecting means shall be installed for mobile and portable high-voltage equipment according to the requirements of Part VIII of Article 230 and shall disconnect all ungrounded conductors. [495.61(D)](https://2023.antflix.net#495.61(D))
https://2023.antflix.net#495.61(D)
Chapter 4 Equipment for General Use
495.62
Motors driving single or multiple dc generators supplying a system operating on a cyclic load basis shall not require overload protection if 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 pro...
https://2023.antflix.net#495.62
Chapter 4 Equipment for General Use
495.63
All energized switching and control parts shall be enclosed in grounded metal cabinets or enclosures. These cabinets or enclosures shall be marked DANGER - HIGH VOLTAGE - KEEP OUT and shall be locked so that only authorized and qualified persons can enter. The danger marking(s) or label(s) shall comply with 110.21(B). ...
https://2023.antflix.net#495.63
Chapter 4 Equipment for General Use
495.64
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. [495.64](https://2023.antflix.net#495.64)
https://2023.antflix.net#495.64
Chapter 4 Equipment for General Use
495.65
A metallic enclosure shall be provided on the mobile machine for enclosing the terminals of the power cable. The enclosure shall include terminal connections to the machine frame for the equipment grounding conductor. Ungrounded conductors shall be attached to insulators or be terminated in approved high-voltage cable ...
https://2023.antflix.net#495.65
Chapter 4 Equipment for General Use
495.66
Flexible high-voltage cable supplying power to portable or mobile equipment shall comply with the grounding and bonding requirements in Parts V, VI, and X of Article 250 and the flexible cable requirements in Part III of Article 400. [495.66](https://2023.antflix.net#495.66)
https://2023.antflix.net#495.66
Chapter 4 Equipment for General Use
495.70
The provisions of Part V shall apply to boilers operating over 1000 volts, nominal, in which heat is generated by the passage of current between electrodes through the liquid being heated. [495.70](https://2023.antflix.net#495.70)
https://2023.antflix.net#495.70
Chapter 4 Equipment for General Use
495.71
Boilers shall be supplied only from a 3-phase, 4-wire solidly grounded wye system, or from isolating transformers arranged to provide such a system. Control circuit voltages shall not exceed 150 volts, shall be supplied from a grounded system, and shall have the controls in the ungrounded conductor. [495.71](https://20...
https://2023.antflix.net#495.71
Chapter 4 Equipment for General Use
495.72(A)
Each boiler shall be supplied from an individual branch circuit rated not less than 100 percent of the total load. [495.72(A)](https://2023.antflix.net#495.72(A))
https://2023.antflix.net#495.72(A)
Chapter 4 Equipment for General Use
495.72(B)
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. [495.72(B)](https://2023.antflix.net#495.72(B))
https://2023.antflix.net#495.72(B)
Chapter 4 Equipment for General Use
495.72(C)
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. [495.72(C)](https://2023.antflix.net#495.72(C))
https://2023.antflix.net#495.72(C)
Chapter 4 Equipment for General Use
495.72(D)
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 7 1/2 percent of the boiler full-load current for 10 seconds or exceeds an instantaneous va...
https://2023.antflix.net#495.72(D)
Chapter 4 Equipment for General Use
495.72(E)
The grounded neutral conductor shall be as follows: Connected to the pressure vessel containing the heating elementsInsulated for not less than 1000 voltsHave not less than the ampacity of the largest ungrounded branch-circuit conductorInstalled with the ungrounded conductors in the same raceway, cable, or cable tray, ...
https://2023.antflix.net#495.72(E)
Chapter 4 Equipment for General Use
495.73
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 heating elements. Such means shall be in addition to the temperature, pressure, or both, regulating systems and pressure relief or safety valves. [495.73](h...
https://2023.antflix.net#495.73
Chapter 4 Equipment for General Use
495.74
All exposed non-current-carrying metal parts of the boiler and associated exposed metal structures or equipment shall be bonded to the pressure vessel or to the neutral conductor to which the vessel is connected in accordance with 250.102, except the ampacity of the bonding jumper shall not be less than the ampacity of...
https://2023.antflix.net#495.74
Chaptewr 5 Special Occupancies
500.1(A)
This article covers area classification and general requirements for electrical and electronic equipment and wiring rated at all voltages where fire or explosion hazards might exist due to flammable gases, flammable liquid—produced vapors, combustible liquid—produced vapors, combustible dusts, combustible fibers/flying...
https://2023.antflix.net#500.1(A)
Chaptewr 5 Special Occupancies
500.1(B)
This article does not cover electrical and electronic equipment and wiring rated at all voltages for the following: Zone 0, Zone 1, or Zone 2 hazardous (classified) locationsZone 20, Zone 21, or Zone 22 hazardous (classified) locationsLocations subject to the unique risk and explosion hazards associated with explosives...
https://2023.antflix.net#500.1(B)
Chaptewr 5 Special Occupancies
500.4
Areas designated as hazardous (classified) locations or determined to be unclassified shall be documented on an area classification drawing and other associated documentation. This documentation shall be available to the authority having jurisdiction (AHJ) and those authorized to design, install, inspect, maintain, or ...
https://2023.antflix.net#500.4
Chaptewr 5 Special Occupancies
500.5(A)(1)
Locations shall be classified depending on the properties of the flammable gas, flammable liquid—produced vapor, combustible liquid—produced vapors, combustible dusts, or fibers/flyings that could be present, and the likelihood that a flammable or combustible concentration or quantity is present. Each room, section, or...
https://2023.antflix.net#500.5(A)(1)
Chaptewr 5 Special Occupancies
500.5(A)(2)
Refrigerant machinery rooms that contain ammonia refrigeration systems and are equipped with adequate mechanical ventilation that operates continuously or is initiated by a detection system at a concentration not exceeding 150 ppm shall be permitted to be classified as "unclassified" locations. Informational Note: See ...
https://2023.antflix.net#500.5(A)(2)
Chaptewr 5 Special Occupancies
500.5(B)
Class I locations are those in which flammable gases, flammable liquid—produced vapors, or combustible liquid—produced vapors are or may be present in the air in quantities sufficient to produce explosive or ignitible mixtures. Class I locations shall include those specified in 500.5(B)(1) and (B)(2). [500.5(B)](https:...
https://2023.antflix.net#500.5(B)
Chaptewr 5 Special Occupancies
500.5(B)(1)
A Class I, Division 1 location is a location: In which ignitible concentrations of flammable gases, flammable liquid—produced vapors, or combustible liquid—produced vapors can exist under normal operating conditions, orIn which ignitible concentrations of such flammable gases, flammable liquid—produced vapors, or combu...
https://2023.antflix.net#500.5(B)(1)
Chaptewr 5 Special Occupancies
500.5(B)(2)
A Class I, Division 2 location is a location: In which volatile flammable gases, flammable liquid-produced vapors, or combustible liquid—produced vapors are handled, processed, or used, but in which the liquids, vapors, or gases will normally be confined within closed containers or closed systems from which they can es...
https://2023.antflix.net#500.5(B)(2)
Chaptewr 5 Special Occupancies
500.5(C)
Class II locations are those that are hazardous because of the presence of combustible dust. Class II locations shall include those specified in 500.5(C)(1) and (C)(2). [500.5(C)](https://2023.antflix.net#500.5(C))
https://2023.antflix.net#500.5(C)
Chaptewr 5 Special Occupancies
500.5(C)(1)
A Class II, Division 1 location is a location: In which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitible mixtures, orWhere mechanical failure or abnormal operation of machinery or equipment might cause such explosive or ignitible mixtures to be ...
https://2023.antflix.net#500.5(C)(1)
Chaptewr 5 Special Occupancies
500.5(C)(2)
A Class II, Division 2 location is a location: In which combustible dust due to abnormal operations may be present in the air in quantities sufficient to produce explosive or ignitible mixtures; orWhere combustible dust accumulations are present but are normally insufficient to interfere with the normal operation of el...
https://2023.antflix.net#500.5(C)(2)
Chaptewr 5 Special Occupancies
500.5(D)
Class III locations shall be locations meeting the requirements of 500.5(D)(1) and (D)(2). [500.5(D)](https://2023.antflix.net#500.5(D))
https://2023.antflix.net#500.5(D)
Chaptewr 5 Special Occupancies
500.5(D)(1)
Class III, Division 1 locations shall include those locations specified in 500.5(D)(1)(a) and (D)(1)(b). Combustible Fibers/Flyings. Locations where nonmetal combustible fibers/flyings are in the air under normal operating conditions in quantities sufficient to produce explosible mixtures or where mechanical failure or...
https://2023.antflix.net#500.5(D)(1)
Chaptewr 5 Special Occupancies
500.5(D)(2)
Class III, Division 2 locations shall include those locations specified in 500.5(D)(2)(a) and (D)(2)(b). Combustible Fibers/Flyings. Locations where nonmetal combustible fibers/flyings might be present in the air in quantities sufficient to produce explosible mixtures due to abnormal operations or where accumulations o...
https://2023.antflix.net#500.5(D)(2)
Chaptewr 5 Special Occupancies
500.6(A)
Class I groups shall be in accordance with 500.6(A)(1) through (A)(4). Informational Note No. 1: The explosion characteristics of air mixtures of gases or vapors vary with the specific material involved. For Class I locations, Groups A, B, C, and D, the classification involves determinations of maximum explosion pressu...
https://2023.antflix.net#500.6(A)
Chaptewr 5 Special Occupancies
500.6(A)(1)
Acetylene. [497:3.3.5.1.1] [500.6(A)(1)](https://2023.antflix.net#500.6(A)(1))
https://2023.antflix.net#500.6(A)(1)
Chaptewr 5 Special Occupancies
500.6(A)(2)
Flammable gas, flammable liquid—produced vapor, or combustible liquid—produced vapor mixed with air that may burn or explode, having either a maximum experimental safe gap (MESG) value less than or equal to 0.45 mm or a minimum igniting current ratio (MIC ratio) less than or equal to 0.40. [497:3.3.5.1.2] Informational...
https://2023.antflix.net#500.6(A)(2)
Chaptewr 5 Special Occupancies
500.6(A)(3)
Flammable gas, flammable liquid—produced vapor, or combustible liquid—produced vapor mixed with air that may burn or explode, having either a maximum experimental safe gap (MESG) value greater than 0.45 mm and less than or equal to 0.75 mm, or a minimum igniting current (MIC) ratio greater than 0.40 and less than or eq...
https://2023.antflix.net#500.6(A)(3)
Chaptewr 5 Special Occupancies
500.6(A)(4)
Flammable gas, flammable liquid—produced vapor, or combustible liquid—produced vapor mixed with air that may burn or explode, having either a maximum experimental safe gap (MESG) value greater than 0.75 mm or a minimum igniting current (MIC) ratio greater than 0.80. [497:3.3.5.1.4] Informational Note No. 1: A typical C...
https://2023.antflix.net#500.6(A)(4)
Chaptewr 5 Special Occupancies
500.6(B)
Combustible dust shall be grouped in accordance with 500.6(B)(1) through (B)(3). [500.6(B)](https://2023.antflix.net#500.6(B))
https://2023.antflix.net#500.6(B)
Chaptewr 5 Special Occupancies
500.6(B)(1)
Atmospheres containing combustible metal dusts, including aluminum, magnesium, and their commercial alloys, or other combustible dusts whose particle size, abrasiveness, and conductivity present similar hazards in the use of electrical equipment. [499:3.3.8.1.1] Informational Note: Certain metal dusts may have characte...
https://2023.antflix.net#500.6(B)(1)
Chaptewr 5 Special Occupancies
500.6(B)(2)
Atmospheres containing combustible carbonaceous dusts that have more than 8 percent total entrapped volatiles (see ASTM D3175-2017, Standard Test Method for Volatile Matter in the Analysis Sample of Coal and Coke, for coal and coke dusts) or that have been sensitized by other materials so that they present an explosion...
https://2023.antflix.net#500.6(B)(2)
Chaptewr 5 Special Occupancies
500.6(B)(3)
Atmospheres containing combustible dusts not included in Group E or Group F, including flour, grain, wood, plastic, and chemicals. [499:3.3.8.1.3] Informational Note No. 1: See NFPA 499, Recommended Practice for the Classification of Combustible Dusts and of Hazardous (Classified) Locations for Electrical Installations...
https://2023.antflix.net#500.6(B)(3)
Chaptewr 5 Special Occupancies
500.6(C)
Combustible fibers/flyings shall not be further grouped. [500.6(C)](https://2023.antflix.net#500.6(C))
https://2023.antflix.net#500.6(C)
Chaptewr 5 Special Occupancies
500.6(D)
Ignitible fibers/flyings shall not be further grouped. [500.6(D)](https://2023.antflix.net#500.6(D))
https://2023.antflix.net#500.6(D)
Chaptewr 5 Special Occupancies
500.7
Electrical and electronic equipment in hazardous (classified) locations shall be protected by one or more of the techniques in 500.7(A) through (P). Suitability of the protection techniques for specific hazardous locations is shown in Chapter 9, Table 13. [500.7](https://2023.antflix.net#500.7)
https://2023.antflix.net#500.7
Chaptewr 5 Special Occupancies
500.7(A)
This protection technique shall be permitted for equipment in Class I, Division 1 or 2 locations. [500.7(A)](https://2023.antflix.net#500.7(A))
https://2023.antflix.net#500.7(A)
Chaptewr 5 Special Occupancies
500.7(B)
This protection technique shall be permitted for equipment in Class II, Division 1 or 2 locations. [500.7(B)](https://2023.antflix.net#500.7(B))
https://2023.antflix.net#500.7(B)
Chaptewr 5 Special Occupancies
500.7(C)
This protection technique shall be permitted for equipment in Class II, Division 2 or Class III, Division 1 or 2 locations. [500.7(C)](https://2023.antflix.net#500.7(C))
https://2023.antflix.net#500.7(C)