National Electrical Installation Standards

Standards as High as Your Own

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  • January 15, 2020

    My husband is installing landscape lighting in our front yard and he is trying to determine how deep to bury the underground wires. Any guidelines would be so appreciated. Mary Christianson
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  • January 14, 2020

    What is the minimum size branch circuit conductor for a 50 HP, 3-phase, 460-volt motor that runs continuous and is installed in a steady ambient temperature of 85-90 degrees F? Our office is having a debate about this and we were hoping your forum could provide another view/opinion. Thomas Clark
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  • January 13, 2020

    If I used a length of 1-inch aluminum rigid conduit (10-foot sleeve) for physical protection of a grounding electrode conductor installed on a wall, is bonding required from the contained grounding electrode conductor to the conduit at both ends where the conductor enters the sleeve and where it exits? Thanks for any clarification you can provide. Alex Holtz
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  • January 10, 2020

    Does all electrical equipment have to be UL approved? Mark Goldberg
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  • January 9, 2020

    Does the NEC have a requirement for oxidation inhibitors for connections involving aluminum conductors? Alan Hunt
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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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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.

NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. NEIS can be purchased in the NECA Store in three formats: a printed or PDF download of a standard or, as an annual subscription service.

NECA SAFETY PRODUCTS & PUBLICATIONS: NECA produces electrical safety publications and products for the industry including jobsite safety guides, handbooks and resource kits. View a full listing of available resources and products »

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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