E2 Systems and Equipment 5

Question 1

A commercial building's 277/480V lighting panelboard serves fluorescent fixtures with electronic ballasts. The inspector notes the neutral is undersized. Why is this a concern?

Accepted Answer

Electronic ballasts generate 3rd-order harmonics that add on the neutral, potentially causing it to carry more current than the phase conductors

Answer

Electronic ballasts and nonlinear loads produce triplen harmonics that accumulate on the neutral conductor, requiring it to be upsized per NEC 310.15(E).

Question 2

Under NEC Article 517, in a hospital's patient care area, the general care area (Category 1) requires that receptacles and fixed equipment be connected to which power system?

Accepted Answer

Essential electrical system (EES) — equipment branch

Answer

NEC 517.18 requires that patient bed locations in Category 1 (general care) spaces be served by the essential electrical system's equipment branch.

Question 3

During a commercial inspection, you observe that flexible metal conduit (FMC) is used for a 6-foot equipment connection at a motor. Under NEC 250.118(5), this FMC can serve as a grounding conductor only if it meets which condition?

Accepted Answer

The FMC is listed and the circuit conductors are 10 AWG or smaller, and the FMC does not exceed 6 feet

Answer

NEC 250.118(5) allows listed FMC to serve as a grounding conductor if conductors inside are 10 AWG or smaller and total length does not exceed 6 feet.

Question 4

A commercial building's 2000A service uses a ground fault protection (GFP) system. Per NEC 230.95, GFP is required when the service exceeds:

Accepted Answer

800A at 277/480V or higher grounded wye systems

Answer

NEC 230.95 requires ground fault protection for solidly grounded wye services of more than 150 volts to ground but not exceeding 600V phase-to-phase, rated 800A or more.

Question 5

When inspecting a commercial occupancy's air-conditioning system with a hermetic refrigerant motor-compressor, the branch circuit overcurrent protection is permitted to be sized up to:

Accepted Answer

225% of the nameplate rated-load current

Answer

NEC 440.22(A) allows the branch circuit overcurrent protection for a hermetic refrigerant motor-compressor to be sized up to 225% of the nameplate rated-load current.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Systems and Equipment 5