National Electrical Installation Standards

Standards as High as Your Own

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  • October 3, 2018

    Article 590.4(H) allows flexible cords and cables to pass through doorways or other pinch points. Does it also allow them to run through holes in walls? Craig Schumann
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  • October 2, 2018

    Art 620.21 wiring methods allows MC Cable. The elevator inspector is telling the contractor he cannot use MC in the hoistway as per 620.21 (A)(1). He is stating that MC is the same as FMC and cannot be used in lengths over 6 ft. I would appreciate your input THOMAS J. COUCH
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  • October 1, 2018

    Continuous lighting loads in a commercial building shall be calculated at what percent of the total VA or amperage rating of the branch circuit? Michael Gomes
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  • September 27, 2018

    Are push connectors allowed for connecting no#12 wire in a junction box. I would think not. but need clarification. They fall off. I found these in a repair one day. Jeff Koch
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  • September 26, 2018

    Is so hard usage cable allowed to be run in cable tray. 3phase system. Edward Lohutko
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  • September 25, 2018

    Is it ever okay to use a 15amp switch with a 20 amp circuit breaker. Donna Betchner
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  • September 24, 2018

    I am replacing a direct wired garbage disposal with a plugin disposal. Do I need to install GFCI outlet or can I use just a grounded outlet? Michael Williams
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  • September 21, 2018

    Can you phase the neutral wire and use it for a conductor for an ac unit? Larry Miller
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  • September 20, 2018

    Is it necessary to protect an existing older hard wired community pool with GFCI? It is a 5HP- 208 Volt - 3 Phase pump? Fred Cocks
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  • September 19, 2018

    Good morning, First, thank you for continuing this forum. I was recently called on to connect a radon blower. The installer left a switch kit provided from the blower manufacturer. I don’t know if the kit comes with the blower or if it is a separate item purchased by the radon mitigation contractor. The kit contained a weatherproof box, switch, weatherproof cover, two liquid- tight cord connectors and a 30 inch piece of SJOW cord. An image of the kit can be seen here: https://www.radonaway.com/products/radon-system-accessories/outdoor-fan-covers-accessories/kit-sf180-elec-out-switch-kit.php. It is billed as an exterior switch kit. 400.12(1) states that cord cannot be used as a substitute for fixed wiring unless specifically permitted in 400.10. This installation does not seem to fit any of the uses permitted in 400.10(A). The blower is connected to the rigid 3” piping with flexible couplings and pipe clamps to allow replacement without cutting into the fixed piping. But it should not need frequent repair or changing. I think it might be a stretch saying it complies with 400.10(A)(8). There is nothing in the instructions supplied with the blower that mentions the switch kit, only that the installation must be done according to the NEC. There were no instructions supplied with the switch kit. Do you think installing the blower using the cord in this kit is acceptable? Bob
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  • September 18, 2018

    What is the maximum allowable height that a panel box can be installed from the floor? Philip Muldoon
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  • September 17, 2018

    Re: CQD answer published Wednesday, September 5, 2018 - Load Calculations Load calculations per 220.83 existing building. I'm curious how additional loads should added? I have been told by chief electrical inspectors at least 3 different ways. 1. Additional loads at 40% 2. Additional loads at 100% 3. Additional loads at 125% I understand the misunderstanding. I've been told to use the 40% rule because that's what we'll be used the next time then additional loan is added.. makes sense. So I understanding the two other additional load calculations are extrapolated from other parts of the code book to make it more difficult to add additional loads to the existing structure? Are any of these methods correct or following the code as it is written? I am aware of how the rest of the calculation is done the first 10000 volt amps at 100% and the remainder at 40%. But the NEC does not specifically say additional loads at 40% or what percentage it should be added in at? Any help in this matter would be greatly appreciated. And as always Charlie thank you for the code question of the day and all of your great work answering our questions! Thanks, Oliver Allen
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  • September 14, 2018

    I need the code # for Lighting in Machine work space Francis Scarnati
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  • September 13, 2018

    Charlie, I enjoy reading your questions and answers every weekday. I am currently in a debate with a co-worker over 410.36(B) regarding lay in fixtures in suspended ceilings. My position is that as long as the fixture is secured to the grid via listed clips, screws, bolts, rivets, etc, there is nothing I can fail the installation on as an electrical inspector. He contends that the light must be secured to the building structure by at least 2 support wires stating that we do not know whether or not the ceiling is rated to support the fixture. I argue that that would be a building code issue and therefore fall on the building inspector to enforce an not the electrical inspector. Who is correct or are we both partially correct in some aspects? Regards, Jeff
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  • September 12, 2018

    Re: CQD answer published Monday, September 3, 2018 -Swimming Pool Lighting Charlie, here is some additional information about pools and hot tubs. The Model Aquatic Health Code (MAHC) https://www.cdc.gov/mahc/editions/current.html Tammy
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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.

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