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Conductors and Branch Circuits Flashcards

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

Read the first 6 Conductors and Branch Circuits flashcards as text

  1. An electrician installs a 120/240V single-phase multiwire branch circuit using two single-pole circuit breakers. To comply with NEC® 210.4(B), what additional component is required at the panelboard where the circuit originates?

    Answer: An identified handle tie.

    NEC® 210.4(B) requires that each multiwire branch circuit be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. This can be achieved with a 2-pole circuit breaker or by using two single-pole circuit breakers with an identified handle tie to connect the operating handles.

  2. A conduit contains five current-carrying 8 AWG THHN copper conductors. According to NEC® Table 310.16, the ampacity of an 8 AWG THHN conductor is 55A at 90°C. What is the adjusted ampacity of each conductor after applying the adjustment factor from Table 310.15(C)(1)?

    Answer: 44.0A

    According to NEC® Table 310.15(C)(1), when there are 4-6 current-carrying conductors in a raceway, their ampacity must be adjusted to 80% of the value listed in Table 310.16. Therefore, the adjusted ampacity is 55A * 0.80 = 44A.

  3. What is the minimum required ampacity for a branch circuit conductor supplying a continuous load of 22A and a noncontinuous load of 10A?

    Answer: 37.5A

    Per NEC® 210.19(A)(1), branch-circuit conductors must have an ampacity not less than the sum of the noncontinuous load plus 125% of the continuous load. The calculation is: (22A * 1.25) + 10A = 27.5A + 10A = 37.5A.

  4. According to NEC® 210.8(A), which of the following areas in a newly constructed dwelling unit requires GFCI protection for all 125V, single-phase, 15- and 20-ampere receptacles?

    Answer: A finished basement.

    Recent updates to NEC® 210.8(A)(5) have expanded the requirement for GFCI protection to include ALL basement areas in dwelling units, whether they are finished or unfinished. Hallways, closets, and typical home offices do not have a specific requirement for GFCI protection unless other conditions apply (e.g., proximity to a sink).

  5. In a habitable room of a dwelling, what is the maximum distance a receptacle can be from any point measured horizontally along the floor line of an unbroken wall space?

    Answer: 6 feet

    NEC® 210.52(A)(1) states that receptacles in habitable rooms of a dwelling must be installed so that no point measured horizontally along the floor line in any wall space is more than 6 feet from a receptacle outlet. This effectively means receptacles can be spaced a maximum of 12 feet apart.

  6. A 15-ampere branch circuit supplies both lighting outlets and receptacle outlets in a commercial office. What is the maximum rating of any single cord-and-plug-connected piece of equipment that is NOT fastened in place that can be used on this circuit?

    Answer: 12 amperes

    According to NEC® 210.23(A)(1), on a 15- or 20-ampere branch circuit that supplies two or more outlets, the rating of any one cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80% of the branch-circuit rating. For a 15-ampere circuit, this is 15A * 0.80 = 12A.