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Class II, Division 2. In Class II, Division 2 locations, transformers and resistors shall comply with 502.120(B)(1) through (B)(3). Switching Mechanisms. Switching mechanisms (including overcurrent devices) associated with control transformers, solenoids, impedance coils, and resistors shall be p...

Class II, Division 2. In Class II, Division 2 locations, transformers and resistors shall comply with 502.120(B)(1) through (B)(3). Switching Mechanisms. Switching mechanisms (including overcurrent devices) associated with control transformers, solenoids, impedance coils, and resistors shall be provided with enclosures that are dusttight or otherwise identified for the location. Coils and Windings. Where not located in the same enclosure with switching mechanisms, control transformers, solenoids, and impedance coils shall be provided with enclosures that are dusttight or otherwise identified for the location. Resistors. Resistors and resistance devices shall have dust-ignitionproof enclosures that are dusttight or otherwise identified for the location. 502.125 Motors and Generators. (A) Class II, Division 1. In Class II, Division 1 locations, motors, generators, and other rotating electrical machinery shall be in conformance with either of the following: (1) Identified for the location Totally enclosed pipe-ventilated ENHANCED CONTENT Collapse In a pipe-ventilated system, the supply and exhaust of air from/ to outside the Class II area is through a closed pipe system. This prevents accumulation of dust inside the totally enclosed equipment. Class II, Division 2. In Class II, Division 2 locations, motors, generators, and other rotating electrical equipment shall be totally enclosed nonventilated, totally enclosed pipe-ventilated, totally enclosed water-air-cooled, totally enclosed fan-cooled, or dust-ignitionproof, for which maximum full-load external temperature shall be in accordance with 500.8(D)(2) for normal operation when operating in free air (not dust blanketed) and shall have no external openings. Exception: If the authority having jurisdiction believes accumulations of nonconductive, nonabrasive dust will be moderate and if machines can be easily reached for routine cleaning and maintenance, the following shall be permitted to be installed: (1) Standard open-type machines without sliding contacts, centrifugal or other types of switching mechanism (including motor overcurrent, overloading, and overtemperature devices), or integral resistance devices (2) Standard open-type machines with such contacts, switching mechanisms, or resistance devices enclosed within dusttight housings without ventilating or other openings (3) Self-cleaning textile motors of the squirrel-cage type (4) Machines with sealed bearings, bearing isolators, and seals ENHANCED CONTENT Collapse Totally enclosed motors are permitted in Class II, Division 2 locations if the external surface temperatures, without a dust blanket, do not exceed the temperatures indicated under the maximum full-load (normal operation) conditions in500.8(D)(2). Totally enclosed fan-cooled (TEFC) motors should be examined carefully to verify that there are no external openings, even though the motor may be marked TEFC. 502.128 Ventilating Piping. Ventilating pipes for motors, generators, or other rotating electrical machinery, or for enclosures for electrical equipment, shall be of metal not less than 0.53 mm (0.021 in.) in thickness or of equally substantial noncombustible material and shall comply with all of the following: (1) Lead directly to a source of clean air outside of buildings Be screened at the outer ends to prevent the entrance of small animals or birds Be protected against physical damage and against rusting or other corrosive influences Ventilating pipes shall also comply with 502.128(A) and (B). Class II, Division 1. In Class II, Division 1 locations, ventilating pipes, including their connections to motors or to the dust-ignitionproof enclosures for other equipment, shall be dusttight throughout their length. For metal pipes, seams and joints shall comply with one of the following: Be riveted and soldered Be bolted and soldered Be welded Be rendered dusttight by some other equally effective means Class II, Division 2. In Class II, Division 2 locations, ventilating pipes and their connections shall be sufficiently tight to prevent the entrance of appreciable quantities of dust into the ventilated equipment or enclosure and to prevent the escape of sparks, flame, or burning material that might ignite dust accumulations or combustible material in the vicinity. For metal pipes, lock seams and riveted or welded joints shall be permitted; and tight-fitting slip joints shall be permitted where some flexibility is necessary, as at connections to motors. 502.130 Luminaires. ENHANCED CONTENT Collapse All lighting equipment in Class II, Division 1 locations and all portable lighting equipment in a Class II, Division 2 location must be identified for such use. If not identified for use in a Class II location, all fixed lighting equipment in a Class II, Division 2 location must be dusttight. Section 502.130 requires luminaires in Class II locations to be marked to indicate maximum lamp wattage. In addition, lamps must be guarded or protected by their location to prevent damage that could allow the escape of sparks or burning material. Below is an example of a listed luminaire suitable for use in Class II, Group E, F, and G locations. (Courtesy of Eaton, Crouse-Hinds Division) Class II, Division 1. In Class II, Division 1 locations, luminaires for fixed and portable lighting shall comply with 502.130(A)(1) through (A)(4). Marking. Each luminaire shall be identified for the location and shall be clearly marked to indicate the type and maximum wattage of the lamp for which it is designed. Physical Damage. Each luminaire shall be protected against physical damage by a suitable guard or by location. Pendant Luminaires. Pendant luminaires shall be suspended by threaded rigid metal conduit stems, by threaded steel intermediate metal conduit stems, by chains with approved fittings, or by other approved means. For rigid stems longer than 300 mm (12 in.), permanent and effective bracing against lateral displacement shall be provided at a level not more than 300 mm (12 in.) above the lower end of the stem, or flexibility in the form of a fitting or a flexible connector listed for the location shall be provided not more than 300 mm (12 in.) from the point of attachment to the supporting box or fitting. Threaded joints shall be provided with set screws or other effective means to prevent loosening. Where wiring between an outlet box or fitting and a pendant luminaire is not enclosed in conduit, flexible cord listed for hard usage shall be permitted to be used in accordance with 502.10(A)(2)(5). Flexible cord shall not serve as the supporting means for a luminaire. Supports. Boxes, box assemblies, or fittings used for the support of luminaires shall be identified for Class II locations. Class II, Division 2. In Class II, Division 2 locations, luminaires shall comply with 502.130(B)(1) through (B)(5). Portable Lighting Equipment. Portable lighting equipment shall be identified for the location. They shall be clearly marked to indicate the maximum wattage of lamps for which they are designed. Fixed Lighting. Luminaires for fixed lighting shall be provided with enclosures that are dusttight or otherwise identified for the location. Each luminaire shall be clearly marked to indicate the maximum wattage of the lamp that shall be permitted without exceeding an exposed surface temperature in accordance with 500.8(D)(2) under normal conditions of use. Physical Damage. Luminaires for fixed lighting shall be protected from physical damage by suitable guards or by location. Pendant Luminaires. Pendant luminaires shall be suspended by threaded rigid metal conduit stems, by threaded steel intermediate metal conduit stems, by chains with approved fittings, or by other approved means. For rigid stems longer than 300 mm (12 in.), permanent and effective bracing against lateral displacement shall be provided at a level not more than 300 mm (12 in.) above the lower end of the stem, or flexibility in the form of an identified fitting or a flexible connector shall be provided not more than 300 mm (12 in.) from the point of attachment to the supporting box or fitting. Where wiring between an outlet box or fitting and a pendant luminaire is not enclosed in conduit, flexible cord listed for hard usage shall be permitted if terminated with a listed cord connector that maintains the protection technique. Flexible cord shall not serve as the supporting means for a luminaire. Electric-Discharge Lamps. Starting and control equipment for electric-discharge lamps shall comply with the requirements of 502.120(B). 502.135 Utilization Equipment. (A) Class II, Division 1. In Class II, Division 1 locations, all utilization equipment shall be identified for the location. Class II, Division 2. In Class II, Division 2 locations, all utilization equipment shall comply with 502.135(B)(1) through (B)(4). Heaters. Electrically heated utilization equipment shall be identified for the location. Exception: Metal-enclosed radiant heating panel equipment shall be permitted to be dusttight and marked in accordance with 500.8(C). (2) Motors. Motors of motor-driven utilization equipment shall comply with 502.125(B). Switches, Circuit Breakers, and Fuses. Enclosures for switches, circuit breakers, and fuses shall comply with 502.115(B). Transformers, Solenoids, Impedance Coils, and Resistors. Transformers, solenoids, impedance coils, and resistors shall comply with 502.120(B). 502.140 Flexible Cords — Class II, Divisions 1 and 2. (A) Permitted Uses. Flexible cords used in Class II locations shall be permitted as follows: (1) For connection between portable lighting equipment or other portable utilization equipment and the fixed portion of its supply circuit. The flexible cord shall be attached to the utilization equipment with a cord connector listed for the protection technique of the equipment wiring compartment. An attachment plug in accordance with 502.145 shall be employed. Where flexible cord is permitted by 502.10(A)(2) for fixed and mobile electrical utilization equipment; where the flexible cord is protected by location or by a suitable guard from damage; and only in a restricted industrial establishment. For electric submersible pumps with means for removal without entering the wet-pit. The extension of the flexible cord within a suitable raceway between the wet-pit and the power source shall be permitted. For electric mixers intended for travel into and out of open-type mixing tanks or vats. For temporary portable assemblies consisting of receptacles, switches, and other devices that are not considered portable utilization equipment but are individually listed for the location. Installation. Where flexible cords are used, the cords shall comply with all of the following: Be of a type listed for extra-hard usage. Exception to (1): Flexible cord listed for hard usage as permitted by 502.130(A)(3) and (B)(4). Contain, in addition to the conductors of the circuit, an equipment grounding conductor complying with 400.23. Be supported by clamps or by other suitable means in such a manner that there will be no tension on the terminal connections. In Division 1 locations, the cord shall be terminated with a cord connector listed for the location or a listed cord connector installed with a seal listed for the location. In Division 2 locations, the cord shall be terminated with a listed dusttight cord connector. Be of continuous length. Where 502.140(A)(5) is applied, cords shall be of continuous length from the power source to the temporary portable assembly and from the temporary portable assembly to the utilization equipment. 502.145 Receptacles and Attachment Plugs. Receptacles and attachment plugs shall be identified for the location. Class II, Division 1. Receptacles. In Class II, Division 1 locations, receptacles shall be part of the premises wiring. Attachment Plugs. Attachment plugs shall be of the type that provides for connection to the equipment grounding conductor of the flexible cord. Class II, Division 2. Receptacles. In Class II, Division 2 locations, receptacles shall be part of the premises wiring. Attachment Plugs. Attachment plugs shall be of the type that provides for connection to the equipment grounding conductor of the flexible cord. 502.150 Signaling, Alarm, Remote-Control, and Communications Systems; and Meters, Instruments, and Relays. (A) Class II, Division 1. In Class II, Division 1 locations, signaling, alarm, remote-control, and communications systems; and meters, instruments, and relays shall comply with 502.150(A)(1) through (A)(3). Contacts. Enclosures containing contacts shall comply with the requirements of 502.150(A)(1)(a) or (A)(1)(b). Switches, circuit breakers, relays, contactors, fuses, and current-breaking contacts for bells, horns, howlers, sirens, and other devices in which sparks or arcs might be produced shall be provided with enclosures identified for the location. Where current-breaking contacts are immersed in oil or where the interruption of current occurs within a chamber sealed against the entrance of dust, enclosures shall be permitted to be of the general-purpose type. Resistors and Similar Equipment. Enclosures containing resistors shall comply with the requirements of 502.150(A)(2)(a) or (A)(2)(b). Resistors, transformers, choke coils, rectifiers, thermionic tubes, and other heat-generating equipment shall be provided with enclosures identified for the location. Where resistors or similar equipment are immersed in oil or enclosed in a chamber sealed against the entrance of dust, enclosures shall be permitted to be of the general-purpose type. Rotating Machinery. Motors, generators, and other rotating electrical machinery shall comply with 502.125(A). Class II, Division 2. In Class II, Division 2 locations, signaling, alarm, remote-control, and communications systems; and meters, instruments, and relays shall comply with 502.150(B)(1) through (B)(4). Contacts. Enclosures for contacts shall comply with the requirements of 502.150(B)(1)(a) or (B)(1)(b). Contacts shall comply with the requirements of 502.150(A)(1) or be installed in enclosures that are dusttight or otherwise identified for the location. Enclosures in nonincendive circuits shall be permitted to be of the general-purpose type. Transformers and Similar Equipment. The windings and terminal connections of transformers, choke coils, and similar equipment shall comply with 502.120(B)(2). Resistors and Similar Equipment. Resistors, resistance devices, thermionic tubes, rectifiers, and similar equipment shall comply with 502.120(B)(3). Rotating Machinery. Motors, generators, and other rotating electrical machinery shall comply with 502.125(B). Connections. To facilitate replacements, process control instruments shall be permitted to be connected through flexible cord, attachment plug, and receptacle if all of the following conditions apply: Attachment plug and receptacle are listed for use in Class II, Division 2 locations, and listed for use with flexible cords. Exception No. 1 to (1): A Class II, Division 2 listing shall not be required if the circuit involves only nonincendive field wiring. Exception No. 2 to (1): In restricted industrial establishments, the Class II, Division 2 listing shall not be required when the requirements of 502.150(B)(5)(2), (B)(5)(3), and (B)(5)(4) are satisfied and the receptacle carries a label warning against plugging or unplugging when energized. (2) The flexible cord does not exceed 900 mm (3 ft), is of a type listed for extra-hard usage, or, if listed for hard usage, is protected by location. Only necessary receptacles are provided. Unless the attachment plug and receptacle are interlocked mechanically or electrically, or otherwise designed so that they cannot be separated when the contacts are energized, and the contacts cannot be energized when the plug and socket outlet are separated, a switch complying with 502.115(B) is provided so that the attachment plug or receptacle is not depended on to interrupt current. Exception to (4): The switch shall not be required if the circuit is nonincendive field wiring. Article 503 Class III Locations Part I. General 503.1 Scope. This article covers the requirements for electrical and electronic equipment and wiring for all voltages in Class III, Division 1 and Division 2 locations where fire or explosion hazards might exist due to nonmetal combustible fibers/flyings or ignitible fibers/flyings. ENHANCED CONTENT Collapse Class III locations usually include textile mills that process cotton, rayon, and other fabrics, where easily ignitible fibers/flyings are present in the manufacturing process. Sawmills and other woodworking plants, where sawdust, wood shavings, and combustible fibers/flyings are present, also can become hazardous locations. However, if wood flour (dust) is present, the location is a Class II, Group G location and not a Class III location. Fibers/flyings are hazardous not only because they are easily ignited, but also because flames quickly spread through them. Such fires travel with a rapidity approaching an explosion and are commonly called flash fires. Class III, Division 1 applies to locations where material is handled, manufactured, or used. Division 2 applies to locations where material is stored or handled but where no manufacturing processes are performed. Unlike Class I and Class II locations, Class III locations do not have material group designations. 503.5 General. Equipment installed in Class III locations shall be able to function at full rating without developing surface temperatures high enough to cause excessive dehydration or gradual carbonization of accumulated fibers/flyings. Informational Note No. 1: See NFPA 505, Fire Safety Standard for Powered Industrial Trucks Including Type Designations, Areas of Use, Conversions, Maintenance, and Operations, for information on electric trucks. Informational Note No. 2: Organic material that is carbonized or excessively dry is highly susceptible to spontaneous ignition. 503.6 Zone Equipment. Equipment listed and marked in accordance with 506.9(C)(2) for Zone 20 locations and with a temperature marking in accordance with 500.8(D)(3) shall be permitted in Class III, Division 1 locations. Equipment listed and marked in accordance with 506.9(C)(2) for Zone 20, Zone 21, or Zone 22 locations and with a temperature marking in accordance with 500.8(D)(3) shall be permitted in Class III, Division 2 locations. Part II. Wiring 503.10 Wiring Methods. Wiring methods shall comply with 503.10(A) or (B). Informational Note: See Article 100 for the definition of restricted industrial establishment [as applied to hazardous (classified) locations]. (A) Class III, Division 1. General. In Class III, Division 1 locations, the following wiring methods shall be permitted: Rigid metal conduit (RMC), PVC conduit, RTRC conduit, intermediate metal conduit (IMC), electrical metallic tubing (EMT), dusttight wireways, or Type MC or Type MI cable with listed termination fittings. Type PLTC cable or Type PLTC-ER cable used in Class 2 and Class 3 circuits, including installation in cable tray systems. The cable shall be terminated with listed fittings. Type PLTC-ER cable shall include an equipment grounding conductor in addition to a drain wire that might be present. Type ITC cable or Type ITC-ER cable as permitted in 335.4 and terminated with listed fittings. Type ITC-ER cable shall include an equipment grounding conductor in addition to a drain wire. Type MV, Type TC, or Type TC-ER cable, including installation in cable tray systems. Type TC-ER cable shall include an equipment grounding conductor in addition to a drain wire that might be present. The cable shall be terminated with listed fittings. Cablebus. In restricted industrial establishments, listed Type P cable with metal braid armor, with an overall jacket, that is terminated with fittings listed for the location, and installed in accordance with Part II of Article 337. If installed in ladder, ventilated trough, or ventilated channel cable trays, cables shall be installed in a single layer, with a space not less than the larger cable diameter between the two adjacent cables unless otherwise protected against dust buildup resulting in increased heat. Informational Note No. 1: See UL 1309A, Outline of Investigation for Cable for Use in Mobile Installations, for information on construction, testing, and marking of Type P cable. Informational Note No. 2: See ANSI/UL 2225, Cables and Cable-Fittings for Use in Hazardous (Classified) Locations, for information on construction, testing, and marking of cable fittings. (2) Boxes and Fittings. All boxes and fittings shall be dusttight. Flexible Connections. Where flexible connections are necessary, one or more of the following shall be permitted: Dusttight flexible connectors Liquidtight flexible metal conduit (LFMC) with listed fittings Liquidtight flexible nonmetallic conduit (LFNC) with listed fittings and bonded in accordance with 503.30(B) Interlocked armor Type MC cable having an overall jacket of suitable polymeric material and installed with listed dusttight termination fittings Flexible cord in accordance with 503.140 For elevator use, an identified elevator cable of Type EO, Type ETP, or Type ETT, shown under the “use” column in Table 400.4 for “hazardous (classified) locations” and terminated with listed dusttight fittings In restricted industrial establishments, listed Type P cable with metal braid armor, with an overall jacket, that is terminated with fittings listed for the location and installed in accordance with Part II of Article 337 Informational Note: See UL 1309A, Outline of Investigation for Cable for Use in Mobile Installations, for information on construction, testing, and marking of Type P cable. Nonincendive Field Wiring. Nonincendive field wiring shall be permitted using any of the wiring methods permitted for unclassified locations. Nonincendive field wiring systems shall be installed in accordance with the control drawing(s). Simple apparatus, not shown on the control drawing, shall be permitted in a nonincendive field wiring circuit if the simple apparatus does not interconnect the nonincendive field wiring circuit to any other circuit. Informational Note: See Article 100 for the definition of simple apparatus. Separate nonincendive field wiring circuits shall be installed in accordance with one of the following: (1) In separate cables In multiconductor cables where the conductors of each circuit are within a grounded metal shield In multiconductor cables where the conductors of each circuit have insulation with a minimum thickness of 0.25 mm (0.01 in.) Class III, Division 2. Wiring methods in Class III, Division 2 locations shall be in accordance with the following: The wiring shall comply with 503.10(A). In sections, compartments, or areas that do not contain machinery and are used solely for storage, open wiring on insulators shall be permitted where installed in accordance with Part II of Article 398, including the condition required by 398.15(C) that protection be provided where conductors are not run in roof spaces and are well out of reach of sources of physical damage. 503.25 Uninsulated Exposed Parts, Class III, Divisions 1 and 2. There shall be no uninsulated exposed parts, such as electrical conductors, buses, terminals, or components, that operate at more than 30 volts (15 volts in wet locations). These parts shall additionally be protected by a protection technique according to 500.7(E), (F), or (G) that is suitable for the location. Exception: As provided in 503.155. ENHANCED CONTENT Collapse Exposed live parts are permitted in Class III, Division 1 and 2 locations provided the voltage does not exceed 30 volts in dry locations or 15 volts in wet locations. Protection techniques permitted for these parts are intrinsically safe or nonincendive. These techniques limit the circuit’s energy to a level incapable of causing ignition of the hazardous area. 503.30 Grounding and Bonding