E2 Commercial Electrical Inspector Systems and Equipment

Question 1

Which of the following wiring methods is permitted for use in a commercial building?

Accepted Answer

Rigid metal conduit (RMC)

Answer

RMC is commonly used in commercial buildings due to its durability and protection against physical damage. NM cable is typically restricted to residential installations, while AC and FCC have limited commercial applications depending on specific conditions and locations per NEC requirements.

Question 2

What is the primary purpose of grounding in a commercial electrical system?

Accepted Answer

To reduce the risk of electric shock and equipment damage

Answer

Grounding provides a low-resistance path to dissipate fault current, protecting personnel from electric shock and preventing equipment damage. It is a critical safety requirement in all electrical installations.

Question 3

A feeder supplying a 3-phase, 208-volt system has a calculated load of 120 amperes. What size copper conductor with THHN insulation is required, assuming no derating factors apply?

Accepted Answer

#4 AWG

Answer

According to NEC Table 310.16, #4 AWG copper with THHN insulation has an ampacity of 125 amperes, which is sufficient for the calculated load of 120 amperes. Always refer to the NEC ampacity tables and consider any applicable adjustments or corrections.

Question 4

What type of overcurrent protection device is typically used to protect a motor circuit?

Accepted Answer

Time-delay fuse

Answer

Time-delay fuses are used in motor circuits to allow the motor to handle its inrush current (starting current) without tripping immediately. This is crucial for motors, which draw higher current during startup.

Question 5

How many receptacles are required in a commercial office space measuring 400 square feet, according to general NEC guidelines?

Accepted Answer

8

Answer

Per NEC Article 210.52(B), commercial office spaces typically require one receptacle per 50 square feet. For 400 square feet, 400 ÷ 50 = 8 receptacles. This ensures adequate power access for typical office equipment.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Commercial Electrical Inspector Systems and Equipment