Practice Test Geeks(E2) E2 Commercial Electrical Inspector Practice Test
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Systems and Equipment Flashcards

7 cards from real E2 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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

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

    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.

  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:

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

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

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

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

    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.

  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?

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

    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.

  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)?

    Answer: 250% of primary rated current

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

  6. When inspecting a commercial occupancy's generator installation, the transfer switch must be located:

    Answer: As close as practical to the loads it serves and away from the normal service equipment unless listed for that purpose

    NEC 700.12(D) and 701.12 require transfer switches to be positioned as close as practical to the loads served, and normal and emergency conductors must not occupy the same enclosure unless a listed transfer switch permits it.

  7. An E2 inspector finds that a commercial data center uses overhead cable trays for power distribution. The NEC requires cable tray fill to be calculated based on:

    Answer: Cross-sectional area of conductors relative to the tray's usable interior cross-section per NEC Article 392

    NEC Article 392.22 governs cable tray fill based on the cross-sectional area of conductors versus the usable interior cross-section of the tray.