IEC Wiring Methods and Materials 2

Question 1

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

Accepted Answer

6 inches

Answer

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

Question 2

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

Accepted Answer

Type AC cable (BX)

Answer

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).

Question 3

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

Accepted Answer

31%

Answer

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

Question 4

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

Accepted Answer

Direct burial in the earth without conduit

Answer

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

Question 5

What does NEC Article 358 govern?

Accepted Answer

Electrical metallic tubing (EMT)

Answer

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

IEC - Independent Electrical Contractors Practice Test