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Overcurrent Protection & Grounding Flashcards

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

Read the first 7 Overcurrent Protection & Grounding flashcards as text

  1. Which NEC section requires Arc-Fault Circuit-Interrupter (AFCI) protection for bedroom branch circuits in dwelling units?

    Answer: 210.12

    NEC 210.12 mandates AFCI protection for branch circuits supplying outlets in dwelling unit bedrooms and other specified areas.

  2. Under NEC 250.52, which of the following is a permitted grounding electrode?

    Answer: A concrete-encased electrode (Ufer ground)

    NEC 250.52(A)(3) recognizes concrete-encased electrodes (Ufer grounds) as a permitted grounding electrode type.

  3. What is the maximum rating of a fuse or inverse-time circuit breaker that may be used to protect a 10 AWG copper conductor (ampacity 30A) under NEC 240.4(B)?

    Answer: 30 amperes

    Under 240.4(B), the next standard size above conductor ampacity is permitted, but 30A is the exact ampacity so 30A is used directly.

  4. Per NEC 250.66, the size of the grounding electrode conductor (GEC) for a service is based on:

    Answer: The size of the largest service-entrance conductor

    NEC Table 250.66 sizes the GEC based on the largest service-entrance conductor or equivalent area for parallel conductors.

  5. Which statement about double-pole (2-pole) circuit breakers is correct per NEC requirements?

    Answer: They must simultaneously disconnect both ungrounded conductors

    NEC 240.20(B) requires multipole breakers to simultaneously open all ungrounded conductors of the circuit.

  6. NEC 250.4(A)(1) states the purpose of grounding electrical systems is to:

    Answer: Limit voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines

    NEC 250.4(A)(1) specifies grounding limits overvoltage from lightning and other surge events to protect equipment and personnel.

  7. What is the maximum length of a 25-foot feeder tap conductor permitted under NEC 240.21(B)(2) if it terminates in a single circuit breaker?

    Answer: 25 feet

    NEC 240.21(B)(2) allows up to 25-foot tap conductors when the tap terminates in a single overcurrent device and specific ampacity conditions are met.