E2 Plan Review and Inspections 5

Question 1

A commercial plan shows a panelboard installed in a bathroom of an office building. What does the NEC say about this installation?

Accepted Answer

NEC 240.24(E) prohibits overcurrent devices (including panelboards) in bathrooms of any occupancy

Answer

NEC 240.24(E) prohibits overcurrent devices from being located in bathrooms of any occupancy, including commercial buildings.

Question 2

During a plan review, the electrical drawings show conductors with 75°C termination ratings on equipment with 60°C terminal ratings. What is the correct action?

Accepted Answer

Require the conductors to be sized using the 60°C column of NEC Table 310.16 to match the terminal rating per NEC 110.14(C)

Answer

NEC 110.14(C) requires that conductor ampacity be determined based on the lowest temperature rating among all connected devices, so 60°C terminals require using the 60°C column.

Question 3

An inspector is reviewing plans for a commercial building addition. The plans show a new feeder tapped from an existing panelboard busbar using a tap conductor that is smaller than the feeder conductors. Under what conditions does the NEC permit this tap?

Accepted Answer

The tap is permitted if it follows NEC 240.21 tap rules, such as the 10-foot or 25-foot tap rule with appropriate termination at a protected panel

Answer

NEC 240.21 provides tap rules that allow unprotected conductors for limited distances (10 ft, 25 ft, or transformer secondary) if specific conditions are met.

Question 4

A final inspection of a commercial building reveals that some circuit breakers in the main distribution panel are double-tapped (two conductors under one breaker lug). What is the inspector's required action?

Accepted Answer

Require correction unless the breaker is listed and labeled for two conductors per NEC 408.41

Answer

NEC 408.41 prohibits more than one conductor per terminal unless the terminal is identified for multiple conductors.

Question 5

During a commercial building inspection, an inspector checks a transformer room and finds that the primary overcurrent device is rated at 300% of the transformer's primary full-load current. The transformer is 45 kVA, 480-208Y/120V. Is this compliant with the NEC?

Accepted Answer

Yes, NEC 450.3(B) permits primary overcurrent protection up to 300% for certain transformer sizes

Answer

NEC 450.3(B) Table allows primary-only protection up to 300% for transformers where the calculated value does not correspond to a standard overcurrent device rating, depending on the transformer's rating.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Plan Review and Inspections 5