Wiring Methods and Materials Flashcards

What is the minimum bending radius for a 1-inch rigid metal conduit (RMC)?

Answer: 6 inches

NEC Table 344.24 requires a minimum bending radius of 6 times the trade size for 1-inch RMC, which equals 6 inches.

Which wiring method is specifically prohibited in commercial kitchens above a suspended ceiling where the space is used as a return air plenum?

Answer: Type AC cable (BX)

Type AC cable (BX) is not listed for use in plenum spaces; only wiring methods with plenum-rated cables or raceways are permitted per NEC 300.22(C).

When installing conductors in a conduit, what is the maximum fill percentage allowed for three or more conductors?

Answer: 31%

NEC Chapter 9, Table 1 limits conduit fill to 40% for two conductors and 31% for three or more conductors.

Type UF cable is specifically designed and listed for which application?

Answer: Direct burial in the earth without conduit

Type UF (Underground Feeder) cable is listed for direct burial applications per NEC Article 340.

What does NEC Article 358 govern?

Answer: Electrical metallic tubing (EMT)

NEC Article 358 covers the installation requirements for Electrical Metallic Tubing (EMT).

When securing nonmetallic-sheathed cable (NM) to a box, within how many inches of the box must a cable clamp or fitting be installed?

Answer: 12 inches

NEC 334.30(B) requires NM cable to be secured within 12 inches of a box or fitting where a clamp or fitting is required.

What is the minimum cover requirement for Schedule 80 PVC conduit installed under a residential driveway?

Answer: 12 inches

NEC Table 300.5 requires only 12 inches of cover for rigid nonmetallic conduit (Schedule 80) under a residential driveway.