E2 Systems and Equipment 4

Question 1

In a commercial occupancy, which of the following best describes a 'separately derived system' under the NEC?

Accepted Answer

A system whose power is derived from a source with no direct electrical connection to the supply conductors of another system

Answer

NEC Article 100 defines a separately derived system as one with no direct electrical connection to supply conductors of another system, such as a transformer secondary.

Question 2

An inspector is reviewing a commercial installation where a 225A panelboard is fed by aluminum service entrance conductors. Under NEC 310.15, aluminum conductors must be:

Accepted Answer

Terminated at 75°C terminals unless equipment is marked for 90°C

Answer

NEC 310.15(B) requires aluminum conductors to be terminated at equipment rated for 75°C, which must be verified at the termination points.

Question 3

What NEC requirement applies to the installation of a commercial electric vehicle (EV) charging station rated at 7.2 kW, 240V?

Accepted Answer

The branch circuit must be rated at 125% of the EV supply equipment's rated current

Answer

NEC 625.42 requires EV charging equipment to be supplied by a branch circuit rated not less than 125% of the maximum load of the EVSE.

Question 4

During inspection of a commercial rooftop photovoltaic (PV) system, the inspector verifies that all conductors on the roof surface are installed in conduit. Why is this required?

Accepted Answer

To protect conductors from physical damage and UV degradation per NEC 690.31

Answer

NEC 690.31 requires PV system conductors exposed to physical damage or UV on rooftops to be protected in a raceway or listed PV wire rated for the application.

Question 5

A commercial building has a 1000 kVA, 480-120/208V transformer. The primary overcurrent protection must not exceed what value per NEC 450.3(B)?

Accepted Answer

250% of primary rated current

Answer

NEC 450.3(B) Table permits primary overcurrent protection up to 250% of rated primary current when secondary protection is also provided at 125%.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Systems and Equipment 4