National Electrical Installation Standards

Standards as High as Your Own

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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.
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  • 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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  • December 17, 2019

    Re: CQD answers published November 28 and December 10, 2019 -Water Piping Replacement Electrode retrofitting replacement is not in the NEC that I know of, but since so many inspectors read this excellent CQD, I will offer up my solution for losing the metal main water supply line. It details Chuck Mello's mention of a 250.53(D)(2) supplemental electrode. The replacement of the water supply line essentially always requires that a trench be dug. At this time it is very easy to install a supplemental electrode system [250.53(D)(2)]. Place a bare copper conductor in the trench with the new plastic pipe, with at least one but preferably two ground rods [250.52(5) & 250.53(A)(3) & 250.53(B)]. These rods are also driven in the trench, then use direct burial conductor clamps. This creates a "permanent" retrofitted electrode which is not easily damaged. Bare #6 copper would be allowed, but I used 25+ feet of #2, more in compliance with 250.52(A)(4) - an extra $20 cost - and put the rods 20' apart. Scott Cline
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  • December 16, 2019

    Sizing a 480V 3-phase 4-wire service for a waste water pump station. There are (4) 60 HP motors however the mechanical system will only allow (2) pumps to ever run simultaneously. What is the correct way to size the main utility service using the load for the (2) pumps? or do you have to size the service using the load for all (4) pumps.Bob Poteste
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  • December 13, 2019

    Is a conduit under a building slab (inside the perimeter of the building foundation) considered a direct buried conduit? Is there any cover requirement for a conduit under a building slab?Michael Oles
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  • December 12, 2019

    Can a three phase electrical sub panel be installed in a kitchen area in a commercial business?Mark Schultz
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  • December 11, 2019

    Re: CQD answer published Wednesday, December 4, 2019 - Service Point I do not agree. If the transformer primary is supplied by the utility then the transformer is the service point. A grounded conductor would be required to the service disconnect. ThanksMike Bressler
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  • December 10, 2019

    Can you have a kitchen GFCI attached to a bathroom GFCI. When kitchen GFCI is tripped the hall bathroom lights go off.Louis Montalvo
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  • December 9, 2019

    Charlie and Friends, Thank you for this wonderful resource and the continued support to the industry. I read the CQD everyday and get a lot out of the questions and interpretations provided. This response is in regard to the question where the hot and cold water piping was being replaced with PEX and what to do with the grounding electrode conductors from the service. I would have to assume that the PEX replacement is just on the interior piping so it is unknown if the supply water line is still metal or not meeting 250.52(A)(1). As the answer stated, if the water supply is still a valid electrode as described then reconnection of the grounding electrode conductor to some point on the metal water pipe up to 5 feet from the entry to the building is still required. This may mean replacing or extending the existing grounding electrode conductor. If extended then the splice would have to comply with 250.64(C). I believe a good addition the answer given would be to mention 250.53(D)(2) where an additional supplemental electrode is required and that grounding electrode conductor installed to be independent of the metal water pipe. Keep up the good work and look forward to the question and answer everyday.Chuck Mello
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  • December 6, 2019

    Re: CQD answer published Tuesday, November 26, 2019 - Flexible Cord Outdoors Charlie in the question about using SO cord outside you said that it had to be weather or water resistant. What if it is also exposed to the sun? Shelby
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  • December 2, 2019

    Re: CQD answer published Monday, November 11, 2019 -Service Conductors in Building I know, I am mostly retired but still love the Code Question of the Day and still miss Charlie at the Western Section IAEI meetings. We have has some of the best conversations about the Code (what else?) and I loved to win an argument (that didn’t happen often). RE: the Code Question of the Day for Friday, November 8, 2019 It is interesting to me that Mr. Tucker referenced an electric utility actually entering a building. Most electric utilities DO NOT permit their conductors to enter a building since we normally do not use conductors that are tested by a NRTL and they have not passed the vertical flame test. Most of the secondary conductors we use are polyethylene covered for overhead and cross-linked polyethylene for direct burial. For entry into a building, the cross-linked polyethylene URD (normally USE) cable has to be marked USE/XHHW or similar to meet the Code requirements. Take care, Charlie Eldridge
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  • December 3, 2019

    A client owns a 12.6 KV X 480Y277 transformer. This transformer primary is supplied by the utility and is the sole power source for the building. The project electrical engineer shows bonding and grounding of X 0 at the transformer, then just 3 phase conductors to the first disconnecting means. We objected. He replied the the grounded conductor will not serve any neutral load loads, and seems to be treating this like a separately derived system instead of what we think it is, a service entrance. We cited the code requiring that the grounded conductor was required to be brought to the first disconnecting means regardless, and grounded and bonded there in addition to the bonding at the transformer. He is adamant, and we are not willing to knuckel under. The argument seems to center on the private ownership of the transformer. In our opinion, who owns the transformer doesn't matter. Your thoughts might help us bring some sanity. Ron Robertson
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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.

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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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