National Electrical Installation Standards

Standards as High as Your Own

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  • July 17, 1998

    Service conductors installed as open conductors shall have a clearance of not less than __ ft from windows that are designed to be opened. a. ___ 3 b. ___ 5 c. ___ 10 d. ___ 12
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  • July 18, 1998

    Nonmetallic-sheathed cable shall be secured in place at intervals not exceeding __ ft and within 12 in. from every box, cabinet and fitting.
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  • July 19, 1998

    At least __ in. of free conductor shall be left at each outlet, junction, and switch point for splices or the connection of fixtures or devices. a. ___ 3 b. ___ 4 c. ___ 6 d. ___ 8
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  • July 20, 1998

    When an outlet, supplied by an underfloor raceway, is abandoned, discontinued, or removed, the sections of circuit conductors supplying the outlet shall be __ from the raceway.
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  • July 21, 1998

    Grounding electrodes of rods of iron or steel shall be at least __ in. in diameter. a. ___ 1/4 b. ___ 3/8 c. ___ 5/8 d. ___ 3/4
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  • July 22, 1998

    Where a main bonding jumper is a screw only, the screw shall be identified with a __ finish that shall be visible with the screw installed. a. ___ silver b. ___ black c. ___ white d. ___ green
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  • July 23, 1998

    A No. __ grounding conductor that is free from exposure to physical damage shall be permitted to be run along the surface of the building construction without metal covering or protection where it is securely fastened to the construction. a. ___ 2 b. ___ 4 c. ___ 6 d. ___ 8
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  • July 24, 1998

    When applying the 25' feeder tap rule, conductors shall be permitted to be tapped, without overcurrent protection at the tap, to a feeder provided the ampacity of the tap conductors is not less than __ of the rating of the overcurrent device protecting the feeder conductors. a. ___ ½ b. ___ 1/3 c. ___ 1/4 d. ___ 1/8
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  • July 25, 1998

    A circuit breaker with a slash rating, such as 120/240V or 480Y/ 277V, shall be permitted to be applied in a circuit where the nominal voltage of any conductor to ground does not exceed the __ ( lower or higher ) of the two values of the circuit breaker's voltage rating.
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  • July 26, 1998

    Equipment intended to break current at fault levels shall have an __ __sufficient for the nominal circuit voltage and the current that is available at the line terminals of the equipment.
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  • July 27, 1998

    Circuit breakers used as switches in 120-volt and 277-volt fluorescent lighting circuits shall be listed and shall be marked __.
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  • July 28, 1998

    Where a ladder or ventilated trough cable tray, having a usable inside depth of 6 in. or less, contains multiconductor control and/or signal cables only, the sum of the cross-sectional areas of all cables at any cross section shall not exceed __ percent of the interior cross-sectional area of the cable tray. a. ___ 25 b. ___ 30 c. ___ 40 d. ___ 50
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  • July 29, 1998

    Branch-circuit conductors supplying a single motor shall have an ampacity not less than __ percent of the motor full-load current rating. a. ___ 100 b. ___ 110 c. ___ 125 d. ___ 150
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  • July 30, 1998

    Type MC cables rated over 600 volts __ ( shall or shall not ) be permitted to be installed in the same cable tray with cables rated 600 volts or less.
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  • August 4, 1998

    What is required for equipment approved for dry locations only, during building construction? A Throw some plastic over it to protect it from the weather. B Equipment is required by the code to be in a NEMA 3-R enclosure (weatherproof). C You must hold up on the installation of the equipment until the building is enclosed and can keep the equipment dry. D The code does not cover this subject, you must use your own discretion.
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IMPORTANT NOTICE: All answers are based on the latest edition of the National Electrical Code®, unless the question requests a response based on a specific edition. This correspondence is not a formal interpretation of the NEC®. Any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, or any technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services.

ABOUT CHARLIE: Charles M. Trout, better known as Charlie, was a nationally known NEC® expert and author. He served on several NEC® technical committees and is past chairman of CMP-12. In 2006 Charlie was awarded the prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development, and technical training. Charlie was also a member of NECA’s Academy of Electrical Contracting. Charlie’s experienced team of industry experts keep the CQD dialogue and discussions active and informative in the spirit of the man himself, as he wanted.

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