Practice Test Geeks(PC) Professional Electrical Contractor Practice Test
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Electrical System Design & Installation Flashcards

7 cards from real PC 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. Per NEC 430.52, a dual-element time-delay fuse used as motor branch circuit short-circuit and ground-fault protection must not exceed what percentage of the motor's full-load current?

    Answer: 150%

    NEC Table 430.52 allows dual-element time-delay fuses for motor protection up to 175% of the motor's full-load current.

  2. What is the maximum length of flexible conduit (FMC) allowed between a junction box and a recessed luminaire per NEC 410.117(C)?

    Answer: 6 feet

    NEC 410.117(C) limits the flexible conduit connection to recessed luminaires to a maximum of 6 feet.

  3. In a commercial building, what is the general lighting load in volt-amperes per square foot used to calculate feeder and service loads for office occupancies per NEC Table 220.12?

    Answer: 2.0 VA/ft²

    NEC Table 220.12 specifies 3.5 VA per square foot for office buildings for general lighting load calculations.

  4. Under NEC 250.119, equipment grounding conductors that are bare, covered, or insulated must be identified by what color when insulated?

    Answer: Green or green with yellow stripes

    NEC 250.119 requires insulated equipment grounding conductors to be identified by a continuous green color or green with one or more yellow stripes.

  5. When calculating the service load for a residential dwelling with electric heat and air conditioning, what does the NEC permit regarding these two loads?

    Answer: Only the larger of the two loads need be included

    Per NEC 220.60, only the larger of the noncoincident loads (heating or cooling) needs to be included in the service calculation, as they will not operate simultaneously.

  6. A 20A, 120V branch circuit using 12 AWG THHN copper conductors has a run of 150 feet one-way. Approximately what is the voltage drop?

    Answer: 5.4V

    Using VD = (2 × K × I × D) ÷ CM = (2 × 12.9 × 20 × 150) ÷ 6,530 ≈ 11.9V — but with 12 AWG at 20A for 150 ft, VD ≈ 5.4V, which exceeds the 3% recommendation (3.6V).

  7. What NEC section requires that service entrance conductors be protected against physical damage where they pass through a building exterior wall?

    Answer: NEC 230.50

    NEC 230.50 requires service entrance conductors to be protected against physical damage, specifying suitable raceways or other protection where they pass through exterior walls.