National Electrical Installation Standards

Standards as High as Your Own

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  • January 8, 2020

    Can a fuse be installed for the grounded conductor of a circuit? Jordan Casey
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  • January 7, 2020

    In a hospital operating room, which ungrounded conductor supplied by an isolated power system can connect to the grounded conductor terminal of a 125-volt, 15- or 20-ampere, single-phase receptacle? Thanks for the insights provided through the Code Question of the Day. Travis Tripp
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  • January 6, 2020

    Thanks for providing this NEC Code question forum. Can a grounded conductor such as a neutral, be connected to a device on a terminal other than the terminal identified for the grounded conductor? Sammy
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  • January 3, 2020

    Where in the NEC does it say you have to color phase current carrying conductors? This include feeders and branch circuits.Dan Kurel
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  • January 2, 2020

    What class division is a explosion proof apparatus? John Holdcroft
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  • January 1, 2020

    The CQD and answer for Wednesday December 25 did not get published on Tuesday November 12 so we are republishing it. Maybe the Grinch was involved! Re: CQD answer published November 27 & December 6, 2019 -2020 NEC Emergency Disconnects - 2 Thanks to the many readers that sent in comments. We did not publish all of them but concepts included that some local rules already require them without the problems suggested, alarm systems usually have battery backup power, and it is safer to operate a switch than pull a meter. We did not intend to start a discussion about whether an emergency disconnecting means external to certain buildings was warranted or not. That time has long passed. Kevin, you seem to be opposed to the new rule but shared this example of emergency responders being able to access a vehicle engine compartment with a broken hood release which is a similar technique that could be used to remove a lock from a disconnect switch. Much safer than pulling a meter that was energized and carrying current.Too long of a story IF you decide to print my question above, but despite all the attempts at ultimate 100% safety, it can't be done. My mom's car started running poorly, so we pulled into a gas station. I looked around and could hear something, so I bent over and saw a reddish glow coming from the engine compartment. FIRE! So I got my mom and our cat out of the car and pushed it away from the gas pump with the car in neutral. I got back out to try to see what was going on, when suddenly the starter began running. It had shorted out the wiring, causing an electrical fire, which then got going enough to short out the starter, which of course began literally adding fuel to the fire. Another interesting aspect was the fire burnt through the hood release cable, so I couldn't open the hood either, which might have been fortunate. Those firefighters got there, smoke billowing out from the front of the car, even blocking the entire street, and within a second had ripped the hood open and were fighting the fire, it was incredible to see. They had it out quickly, and everybody was OK.
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  • December 31, 2019

    Is their a written specification for the temporary power pole used in the early stages of construction of new projects?Ron Lawson
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  • December 27, 2019

    Does a 208 volt 50 amp 3 phase receptacle and a 20 amp 208 volt single phase receptacle require gfci protection in a commercial kitchen?John Reeves
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  • December 26, 2019

    Re: CQD answer published Monday, December 16, 2019 -Underground Location Thanks for all the work you do at CQD I look forward to reading it every day. My question is for additional information of conduits under a slab from 12-13-2019. Would this type of installation be considered a wet location?Thanks again, Mike Clark
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  • January 1, 0001

    What is the distance requirement for adding a receptacle near a wood burning fireplace mantel? Joe Suiter
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  • December 24, 2019

    Re: CQD answer published November 27 & December 6, 2019 -2020 NEC Emergency Disconnects - 2 Thanks to the many readers that sent in comments. We did not publish all of them but concepts included that some local rules already require them without the problems suggested, alarm systems usually have battery backup power, and it is safer to operate a switch than pull a meter. We did not intend to start a discussion about whether an emergency disconnecting means external to certain buildings was warranted or not. That time has long passed. Kevin, you seem to be opposed to the new rule but shared this example of emergency responders being able to access a vehicle engine compartment with a broken hood release which is a similar technique that could be used to remove a lock from a disconnect switch. Much safer than pulling a meter that was energized and carrying current.Too long of a story IF you decide to print my question above, but despite all the attempts at ultimate 100% safety, it can't be done. My mom's car started running poorly, so we pulled into a gas station. I looked around and could hear something, so I bent over and saw a reddish glow coming from the engine compartment. FIRE! So I got my mom and our cat out of the car and pushed it away from the gas pump with the car in neutral. I got back out to try to see what was going on, when suddenly the starter began running. It had shorted out the wiring, causing an electrical fire, which then got going enough to short out the starter, which of course began literally adding fuel to the fire. Another interesting aspect was the fire burnt through the hood release cable, so I couldn't open the hood either, which might have been fortunate. Those firefighters got there, smoke billowing out from the front of the car, even blocking the entire street, and within a second had ripped the hood open and were fighting the fire, it was incredible to see. They had it out quickly, and everybody was OK.
    View Question & Answer

  • December 23, 2019

    Charlie, For the NEC retrofit requirement for residential homes to tamper-resistant outlets, isn't this essentially rendering all old-stock non-tamper-resistant receptacles obsolete and worthless? Is there any way to comply with this NEC requirement and somehow create a tamper-resistant outlet from a non-tamper-resistant receptacle? Somewhere at some point the NEC has said that "a receptacle cover shall be permitted to be used in place of a tamper-resistant receptacle" but I can't find any reference to that now. Thank you for your help.Kevin Kayden
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  • December 20, 2019

    RE: Code Question of the Day 12/10/19 Can I apply higher voltage 480 to a machine that has a equipment nameplate value of 208 voltage only? Benny Bright
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  • December 19, 2019

    Dear Charlie, I am a student in electrical at a technical high school. While having a theory lesson on services, we developed some questions on the straps on the service conduit. We feel that the straps should be located within 12 inches from the weatherhead. Nowhere in the codebook could we find where it states this. We were wondering if you could elaborate on where to find this in the 2017 NEC code book. If you could find time to get back to us, it would be greatly appreciated. Thank you.Alexis G and Ryan M
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  • December 18, 2019

    Are there any Code provisions regarding removal or reinstallation of wall switches containing mercury?Ken Harris
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ABOUT CQD: The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry, sponsored by EATON. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses.

SUBMIT YOUR CODE QUESTION: Click here to submit a question to for inclusion in an upcoming edition of the Code Question of the Day, or email codequestion@necanet.org

CHARLIE TROUT: 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. Even though Charlie passed away in October of 2015, his work continues in spirit. NECA continues to maintain this question forum for its many subscribers in memory and recognition of all his significant contributions to making the NEC what it is today.

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IMPORTANT NOTICE: Unless the question requests a response based on a specific edition, all answers are based on the latest edition of NFPA 70® National Electrical Code®.

This correspondence is not a formal interpretation of the NEC® and any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, the NEC Correlating Committee any Code-making panel or other electrical technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services. 

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