National Electrical Installation Standards

Standards as High as Your Own

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  • August 20, 1998

    You are placing service equipment in the mechanical room and it is located about 16 feet from the outside wall. Since you are using only 2 sticks of conduit and 1 coupling, the electrical inspector said it was O.K., even though you have no disconnects on the outside. Does this installation meets the requirements of the NEC?
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  • August 21, 1998

    You have installed a new 20 circuit, 100A, 120/240v, 1 phase, 3w service panel, for a new home, and have used all of the available spaces for the circuits. Is this an NEC violation?
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  • August 22, 1998

    A storage battery supplying emergency lighting and power shall maintain not less than 87 1/2% of full voltage for how long?
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  • August 23, 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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  • August 24, 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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  • August 25, 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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  • August 26, 1998

    Isn't it true that service drop conductors must be readily accessible?
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  • August 27, 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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  • August 28, 1998

    How much load must the feeder neutral conductor be capable of carrying, in relation to the connected load?
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  • August 31, 1998

    The __ __ __ may waive specific requirements in the Code or permit alternate methods where it is assured that equivalent objectives can be achieved.
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  • September 1, 1998

    Mandatory rules of the Code are characterized by the use of the word __.
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  • September 11, 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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  • September 14, 1998

    You are wiring a commercial building which is at grade or pedestrian level, are you required to run a sign circuit?
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  • September 15, 1998

    You are going to install a medium-base screw-shell lampholder at a distance of 14' above a floor and supply it with a 277v (nominal, to ground) circuit, will this be a correct installation?
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  • September 16, 1998

    Your customer wants 4 separate services, one each for general service, electric heat rate, fire pump and emergency lights, will the NEC allow that many? A No. B Yes, if the engineer has it laid out that way. C Yes, if the inspector and the power company says it is OK. D None of the above.
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ABOUT CQD: NECA’s Code Question of the Day (CQD) is a leading National Electrical Code® forum for NECA and the industry. The CQD generates a lively dialogue and relative practical and Code-based responses to an ever-increasing and interactive audience.

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.

NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. Visit NECA-NEIS.org for more information. NEISÔ can be purchased in three formats: as paper books, on CD, or as electronic downloads.

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