CEI Commercial & Industrial Systems 3

Question 1

In an industrial plant, a 200A feeder supplies a subpanel. The feeder conductors are 3/0 AWG THWN copper in conduit. What is the allowable ampacity of these conductors at 75°C?

Accepted Answer

200A

Answer

Per NEC Table 310.16, 3/0 AWG THWN copper has an allowable ampacity of 200A at 75°C.

Question 2

Which of the following grounding and bonding requirements applies to metal raceways in a commercial building?

Accepted Answer

Metal raceways that qualify must be bonded to form a continuous EGC path

Answer

NEC 250.118 lists metal raceways such as RMC, IMC, and EMT as acceptable equipment grounding conductors when properly installed and bonded.

Question 3

A commercial kitchen uses a 208V, single-phase, 20A branch circuit for a commercial dishwasher. The circuit conductors must be at least what AWG size (copper, THHN, 75°C terminals)?

Accepted Answer

12 AWG

Answer

A 20A branch circuit requires conductors with an ampacity of at least 20A; 12 AWG copper at 75°C has an ampacity of 20A per NEC Table 310.16.

Question 4

Per NEC Article 440, what determines the branch-circuit rating for a hermetic refrigerant motor-compressor?

Accepted Answer

Rated-load current (RLC) or branch-circuit selection current (BCSC), whichever is greater

Answer

NEC 440.22 requires that the branch-circuit short-circuit protection be based on the greater of the RLC or the BCSC as marked on the nameplate.

Question 5

In a commercial building, what is the minimum burial depth for rigid metal conduit (RMC) installed under a parking lot?

Accepted Answer

12 in

Answer

NEC Table 300.5 requires RMC to be buried a minimum of 6 in, but under a parking lot (not a road subject to heavy vehicles), the standard minimum of 6 in for RMC applies; however, NEC 300.5 Column 1 sets 6 in for RMC in all locations.

(CEI) Certified Electrical Inspector Practice Test

(CEI) Certified Electrical Inspector Practice Test

CEI Commercial & Industrial Systems 3