501-Class I Locations

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I. General

equipment grounding conductor shall be included to provide for electrical continuity of the raceway system and for grounding of non-current-carrying metal parts.

(b) Type Ml cable with termination fittings listed for the location. Type MI cable shall be installed and sup- ported in a manner to avoid tensile stress at the termination fittings.

(c) In industrial establishments with restricted public access, where the conditions of maintenance and

501.1 Scope. Article 501 covers the requirements for electrical and electronic equipment and wiring for all voltages in Class I, Division 1 and 2 locations where fire or explosion hazards may exist due to flammable gases or vapors or flammable liquids.

FPN: For the requirements for electrical and electronic equipment and wiring for all voltages in Class I, Zone
0, Zone 1, or Zone 2 hazardous (classified) locations where fire or explosion hazards may exist due to flammable gases or vapors or flammable liquids, refer to Article 505.

501.5 Zone Equipment Equipment listed and marked in accordance with 505.9(C)(2) for use in Class I, Zone 0, 1, or 2 locations shall be permitted in Class I, Division 2 locations for the same gas and with a suitable temperature class. Equipment listed and marked in accordance with 505.9(C)(2) for use in Class I, Zone 0 locations shall be permitted in Class I, Division 1 or Division 2 locations for the same gas and with a suitable temperature class.

II. Wiring

501.10 Wiring Methods. Wiring methods shall comply with 501.10(A) or (B).

(A) Class I, Division 1.

(1) General. In Class I, Division 1 locations, the wiring methods in (a) through (d) shall be permitted.

(a) Threaded rigid metal conduit or threaded steel in termediate metal conduit.

Exception: Type PVC conduit and Type RTRC conduit shall be permitted where encased in a concrete envelope a minimum of 50 mm (2 in.) thick and provided with not less than 600 mm (24 in.) of cover measured from the top of the conduit to grade. The concrete encasement shall be permitted to be omitted where subject to the provisions of 514.8, Exception No. 2, and

515.8(A). Threaded rigid metal conduit or threaded steel

intermediate metal conduit shall be used for the last 600

mm (24 in.) of the underground run to emergence or to

the point of connection to the aboveground raceway. An

supervision ensure that only qualified persons service the installation, Type MC-HL cable, listed for use in Class I, Zone 1, or Division 1 locations, with a gas/vaportight continuous corrugated metallic sheath, an overall jacket of suitable polymeric material, a separate equipment grounding conductors) in accordance with 250.122, and provided with termination fittings listed for the application.
FPN: See 330.12 for restrictions on use of Type MC cable. (d) In industrial establishments with restricted public

access, where the conditions of maintenance and

supervision ensure that only qualified persons service
the installation, Type ITC-HL cable, listed for use in Class
I, Zone 1, or Division 1 locations, with a gas/vaportight
continuous corrugated metallic sheath, an overall jacket of suitable polymeric material and provided with termination fittings

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