National Electrical Installation Standards

Standards as High as Your Own

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  • October 8, 1998

    You are installing a 200 ampere fused disconnect for an electric furnace. You have installed it on the wall beside the furnace with 40in. of clearance in front of the switch to the side of the furnace. The switch is a 480V, 3 phase, 4w, and the furnace is grounded. Was the inspector correct in turning the installation down for inadequate clearance?
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  • October 9, 1998

    You want to tap only two ungrounded phases from a 480Y/277v feeder to use 480v single phase, is this permitted?
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  • October 12, 1998

    The service entrance conductors were run in square duct located under the service equipment. A Since a water heater is at the end of the square duct, is it OK to run just that circuit to feed the water heater, in the square duct (the water heater circuit is to be fused). B Since a water heater is at the end of the square duct, is it OK to run just that circuit to feed the water heater, in the square duct (the water heater circuit is to be fused with a current limiting fuse and is part of the electric utility's controlled water heater program). C You can't run water heater conductors but you are going to run load management wires in the square duct. This is OK since the load management conductors will be fused. D The code says 'Conductors other than service conductors shall not be installed in the same service raceway or service cable', this means that A, B, and C are wrong.
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  • October 13, 1998

    Isn't it true that service drop conductors must be readily accessible?
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  • October 14, 1998

    An inspector turns down a job because the circuits in the service panel were not identified as to their purpose. Was he correct in his action?
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  • October 15, 1998

    How much load must the feeder neutral conductor be capable of carrying, in relation to the connected load?
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  • October 16, 1998

    How do you determine which is the grounded wire, when wiring a light fixture?
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  • October 19, 1998

    A class B ground-fault circuit-interrupter will trip when the current exceeds what value?
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  • October 20, 1998

    Are you permitted to install a circuit using surface metal raceway (like Wiremold) under a raised floor in a data processing area?
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  • October 21, 1998

    What is the smallest size copper ungrounded service entrance conductor permitted by the NEC? A #14 B #12 C 60A D 100A
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  • October 22, 1998

    I met a guy from the power company who told me I needed to correct my power factor since it is 68%, what does 68% power factor mean and what do I do to correct it??
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  • October 23, 1998

    What is the horsepower rating of a standard 125 volt plug (like the one on a lamp cord)?
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  • October 26, 1998

    You are installing a 208Y/120v, 3 phase, 4w, 1200A service. What insulation level does the grounded conductor have to meet (minimum), for an overhead service installed in conduits?
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  • October 27, 1998

    Which of the following electric discharge lamp contains mercury? A High Pressure Sodium B Mercury Vapor C Metal Halide D All of the above E None of the above, mercury is a dangerous substance and the EPA doesn't allow it's use
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  • October 28, 1998

    Your customer is building a house with a mud-room/bathroom (next to the back door) and says he does NOT want a receptacle installed; may you leave it out?
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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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