6-4
Installation of an Explosion-proof or Dust-ignition-proof Apparatus
(reproduced from the NEC)
CAUTIONS
• Install the apparatus only in hazardous (classified) locations for which the apparatus has been approved.
• The sealing must be a maximum distance of 18 in. (457 mm) from the enclosure.
• Do not open the apparatus enclosure when an explosive atmosphere is present.
1. Class I, Division 1 locations
1.1 Wiring methods
• Threaded rigid metal conduit, threaded steel intermediate metal conduit, or Type MI cable with termina-
tion fittings approved for the location, can be employed
• Threaded joints must be made up of at least five threads fully engaged.
1.2 Sealing
• The sealing must be a maximum distance of 18 in. (457 mm) from the enclosure.
• The sealing of each conduit can be provided with a sealing fitting approved for Class I locations.
• The sealing compound must be approved and must not have a melting point of less than 93°C (200°F).
• The minimum thickness of the sealing compound must not be less than the trade size of the conduit, and
must not under any circumstances be less than 5/8 in. (16 mm).
• Splices and taps must not be made in the fittings.
2. Class I, Division 2 locations
2.1 Wiring methods
• Threaded rigid metal conduit; threaded steel intermediate metal conduit; enclosed gasketed busways; Type
PLTC cable in accordance with the provisions for remote-control, signaling, and power-limited circuits
(see NEC, Article 725); Type ITC cable in cable trays, in raceways, supported by messenger wire, or directly
buried where the cable is listed for this use; or Type MI, MC, MV, or TC cable with approved termination
fittings can be employed.
2.2 Sealing
• Each conduit entering the apparatus enclosure is must be sealed as shown in 1.2.
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