Article 503 Class III Locations
Equipment listed and marked in accordance with 506.9(C)(2) for Zone 20, 21, or 22 locations and with a temperature class of not greater than T120°C (for equipment that may be overloaded) or not greater than T165°C (for equipment not subject to overloading) shall be permitted in Class III, Division 2 locations.
- Rigid metal conduit (Type RMC), Type PVC conduit, Type RTRC conduit, intermediate metal conduit (Type IMC), electrical metallic tubing (EMT), dusttight wireways, or Type MC or MI cable with listed termination fittings.
- Types PLTC and PLTC-ER cable in accordance with Part II or III of Article 725, 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.
- Types ITC and ITC-ER cable as permitted in 727.4 and terminated with listed fittings. Type ITC-ER cable shall include an equipment grounding conductor in addition to a drain wire.
- Type MV, TC, or 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.
- Dusttight flexible connectors
- Liquidtight flexible metal conduit (Type LFMC) with listed fittings
- Liquidtight flexible nonmetallic conduit (Type LFNC) with listed fittings
- Interlocked armor Type MC cable having an overall jacket of suitable polymeric material and installed with listed dusttight termination fittings
- Flexible cord in compliance with 503.140
- For elevator use, an identified elevator cable of Type EO, ETP, or ETT, shown under the "use" column in Table 400.4 for "hazardous (classified) locations" and terminated with listed dusttight fittings
Informational Note: Simple apparatus is defined in Article 100 Part III.
Separate nonincendive field wiring circuits shall be installed in accordance with one of the following:
- 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.)
Exception: In sections, compartments, or areas used solely for storage and containing no machinery, open wiring on insulators shall be permitted where installed in accordance with Article 398, but only on condition that protection as required by 398.15(C) be provided where conductors are not run in roof spaces and are well out of reach of sources of physical damage.
Exception: As provided in 503.155.
Exception: The specific bonding means shall only be required to the nearest point where the grounded circuit conductor and the grounding electrode conductor are connected together on the line side of the building or structure disconnecting means as specified in 250.32(B) if the branch-circuit overcurrent protection is located on the load side of the disconnecting means.
Exception: In locations where, in the judgment of the authority having jurisdiction, only moderate accumulations of lint or flyings are likely to collect on, in, or in the vicinity of a rotating electrical machine and where such machine is readily accessible for routine cleaning and maintenance, one of the following shall be permitted:
- Self-cleaning textile motors of the squirrel-cage type.
- Standard open-type machines without sliding contacts, centrifugal or other types of switching mechanisms, including motor overload devices
- Standard open-type machines having such contacts, switching mechanisms, or resistance devices enclosed within tight housings without ventilating or other openings
- 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 be sufficiently tight, including their connections, to prevent the entrance of appreciable quantities of fibers/flyings into the ventilated equipment or enclosure and to prevent the escape of sparks, flame, or burning material that might ignite accumulations of fibers/flyings 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.
- Be of a type listed for extra-hard usage
- Contain, in addition to the conductors of the circuit, an equipment grounding conductor complying with 400.23
- Be supported by clamps or other suitable means in such a manner that there will be no tension on the terminal connections
- Be terminated with a listed dusttight cord connector
Exception: In locations where, in the judgment of the authority having jurisdiction, only moderate accumulations of lint or flyings are likely to collect in the vicinity of a receptacle, and where such receptacle is readily accessible for routine, cleaning, general-purpose grounding-type receptacles mounted, so as to minimize the entry of fibers/flyings shall be permitted.