Hazardous Location Wiring Flashcards

Which NEC article covers Class III hazardous locations involving ignitable fibers and flyings?

Answer: Article 503

Article 503 addresses Class III locations where easily ignitable fibers or flyings are present but not likely to be in suspension in hazardous quantities.

In a Class I hazardous location, flexible connections to equipment must use which type of fitting?

Answer: Explosion-proof flexible fittings listed for the location

Flexible connections in Class I locations require fittings specifically listed as explosion-proof to maintain the integrity of the hazardous location wiring system.

What is a Zone 0 hazardous location characterized by?

Answer: Flammable gases present continuously or for long periods

Zone 0 is the most hazardous zone where flammable concentrations exist continuously or for long periods during normal operation.

When sealing Class I conduit runs, the sealing compound must have a minimum thickness equal to the trade size of the conduit or what minimum value?

Answer: 5/8 inch

Per NEC 501.15(C), the sealing compound thickness must not be less than the trade size of the conduit and in no case less than 5/8 inch.

Which type of motor is NOT permitted in a Class I, Division 1 location?

Answer: Open drip-proof motor

Open drip-proof motors expose live parts and arcing contacts to the hazardous atmosphere and are not permitted in Class I, Division 1 locations.

Class II, Group G hazardous locations involve which type of combustible dust?

Answer: Grain dusts, flour, starch, and similar agricultural dusts

Group G includes grain dust, flour, starch, sugar, and other combustible dusts of agricultural origin that are less conductive than metal dusts.

For a Class I, Division 2 location, which of the following wiring methods is acceptable?

Answer: Threaded RMC or IMC

Threaded RMC or IMC is acceptable in Class I, Division 2 locations, along with other methods listed in NEC 501.10(B).