Licensed Electrical Contractor Wiring Methods and Materials 2

Question 1

What is the maximum number of 90-degree bends permitted in a single run of rigid metal conduit (RMC) between pull points?

Accepted Answer

Four 90-degree bends

Answer

NEC 358.26 and 344.26 limit conduit runs to the equivalent of four quarter bends (360 total degrees) between pull points, outlets, or junction boxes.

Question 2

Which wiring method is permitted for use in a Class I, Division 1 hazardous location?

Accepted Answer

Rigid metal conduit (RMC)

Answer

NEC Article 501 requires threaded rigid metal conduit or Type MI cable in Class I, Division 1 hazardous locations.

Question 3

When installing Type UF cable underground, what is the minimum burial depth required for a residential branch circuit rated at 120 volts?

Accepted Answer

18 inches

Answer

NEC Table 300.5 requires Type UF cable to be buried a minimum of 24 inches, but under a dwelling unit the depth is 18 inches.

Question 4

Electrical metallic tubing (EMT) is NOT permitted to be used in which of the following locations?

Accepted Answer

Concrete encasement in wet locations

Answer

NEC 358.10 prohibits EMT where subject to severe physical damage or where embedded in concrete in wet locations; RMC or IMC is required instead.

Question 5

What is the minimum size of equipment grounding conductor required for a circuit protected by a 60-ampere overcurrent device using copper conductors?

Accepted Answer

10 AWG

Answer

Per NEC Table 250.122, a 60-ampere overcurrent device requires a minimum 10 AWG copper equipment grounding conductor.

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