National Electrical Installation Standards

Standards as High as Your Own

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  • April 1, 2019

    Re: CQD answer published Monday, March 25, 2019 - DLO Cable The answer states no, I feel the answer should be Yes. DLO cable that is listed to meet NEC requirements is often used for this type of Installations. It is out of the scope of non Industrial electrical installers but I found it to be a great learning opportunity. The rest of your answer say yes it can as long as all items of the installation are specified and used so that the correct terminations and crimp specifications are used. It can be a great answer to wire bending space and knowledge that can make us all great at our installation. Thanks for the daily questions and answers. Look forward them to learn and review code. Bryan Desh
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  • March 29, 2019

    I have a 3 phase 480 Volt contactor. Overcurrent caused the contacts to burn a little and stick together. I pulled it apart after removing it from the circuit. My boss wants me to sand the contacts smooth and put it back in the circuit. Is that against code? Walter Thompson
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  • March 28, 2019

    How many over current devices should two pole circuit breaker considered be ? Safa Benosh
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  • March 27, 2019

    Re: CQD answer published Monday, February 25, 2019 -Wet Location Charlie, I'm a little behind but was wondering why your answer to the Class 2 cable in PVC conduit in a wet location had to be rated for a wet location. If the cable is in the conduit doesn't the conduit protected it from the weather so the inside would be dry? Thanks for the continuing education information, Virginia
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  • March 26, 2019

    I have a 1200 amp vertical busway running thru the E room with a 400 amp bus plug. Does the entry door to this E room require panic hardware and required to swing out to meet NEC 126(C) (3)? BILL RICHARDSON
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  • March 25, 2019

    Thanks for providing the holy cow and yeah I knew that answers to many interesting questions. I have a question about some protective steel plates. An industrial facility has constructed a 1 foot by 1 foot trough in the concrete floor to be used to install a wire basket cable tray. The trough is installed across a walkway that is used by forklifts and personnel. The trough is covered with plate steel to provide the walking and driving surface. A groove in the trough holds the cover in place. Power and control cables from a control cabinet to electrical equipment are installed in the tray that is installed in the trough. The power cables are using voltages up to 480 volt. The basket is bonded with an equipment ground. Are the plate steel covers required to be bonded and secured? Thanks, An Iowa inspector.
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  • March 22, 2019

    Contractor is requesting to spec and use DLO cable from disconnect switch to line reactor on a 480V compressor and from the line reactor to the compressor drive. the new feeder is parallel 350KCMIL and space in the reactor is limited on bend radius, is DLO cable acceptable to use and spec? Christopher Ring
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  • March 21, 2019

    Under sec 400.10 (A) (11) is it permissible to power a wall mountable receptacle with flexible? Michael Gaudette
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  • March 20, 2019

    I watched 2 guys working on a pump that was powered from an MCC two flights down. The first three times they went down and put on locks before working on the pump, after that it was "Don't hit the start button". Should there have been a local disconnect at the pump for lock out? Michael Casey
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  • March 19, 2019

    Section 300.13(A) prohibits splices and taps within raceways. My question centers around a ceiling fan. In certain cases the height of a ceiling requires the fan to use a longer downrod than was originally supplied with the fan. Some downrods are 8' in length. Occasionally, the length of lead wire supplied with the fan is not long enough to span the entire length of the downrod. In these cases, if a connection/splice is made in the downrod, does it violate Section 300.13(A). I guess my basic question is, is the downrod considered a raceway? Bill Walker
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  • March 18, 2019

    Re: CQD answer published Monday, March 5, 2019 -GFCI Accessibility Hello, In regards to your answer below for Monday March 4th, 2019: you stated, “Don't forget you typically need to test GFCI's monthly based on the manufacturer's instructions as stated in 110.3(B).” My question: How is that actually realistically feasible, especially for large facilities that may have hundreds, or even thousands of GFCI’s? Do they hire a person full-time just to endlessly go around testing them, only to start over again each month? I have seen the statement stamped on the GFCI’s, even on the modern self-testing versions. I have even asked the manufacturers themselves about it. They have no further comments/answers, other than that it’s still required on the self-testing models too (the electronics are self-testing/monitoring, but they say that the device still requires a testing/cycling of the physical components too, which can only be done manually) Just wondering if there is any realistic solution that you have heard of. Thx, Perry
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  • March 15, 2019

    Can I feed a 1 phase 200 amp load center with 125 amp wire and circuit breaker? Thomas Donnelly
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  • March 14, 2019

    Re: CQD answer published Wednesday, March 6, 2019 -Existing Installation I assume that the question is about an older system that is 3 wire 3 phase and no ground. This was used by several local power company's in our area when 480 volt machines were first introduced in our area. We had a 480 volt 3 wire system like this in an egg processing plant. At that time the power company only gave us the 480 volt 3 wire power. One of the machines created a short that did not trip any breakers, but created a corner grounded system. Because the short was in one machine only and they were able to continue to operate they did not call us for several days. One maintenance employee was concerned about the 480 volts to ground on 2 phases, but was ordered to just keep everything running. We were able to correct it by identifying the problem and asked the power company to upgrade the transformers to a 4 wire system. We than added an external ground to every machine in the building. The panels and buses at that time were not designed for grounding. Is this plant in Tuesdays question required to bring every machine up to proper grounding? I would think that any new machine on the line must be properly grounded. We have another plant that did not have a neutral on the 480 volt system. Someone started to change the lights to 277 volts and I was called when they had problems. (And ruined several new fixtures.) We installed a dry type indoor transformer to correct this. 480 volt 3 wire primary to 480/277 volt 4 wire secondary. We also installed a new 4 wire panel for the lights. Tom Inman
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  • March 13, 2019

    Re: CQD answer published February 22 and March 4, 2019 -Flexible Cords I had really hoped there would be many more comments and info regarding the difference between cable and cord. My personal overly-simplified impression and rule-of-thumb these days is that: CABLE can be used to connect between components of a system (i.e. robotic arm sections, power supply to powered device, etc) but that only CORD (limited to the insulation types defined in Table 400.4) can touch the floor, and/or connect to bldg power (whether with a plug or hard-wired.) Perry
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  • March 12, 2019

    Re: CQD answer published February 21 & March 1, 2019 -Isolated Phase Conductors Charlie, Most code experts say that the only time you can use an isolated phase installation is per the Exception to 300.3(B)(1). This installation does not appear to be an underground installation. Note, that I don't agree with those experts that say you can only install an isophase installation underground. It appears to me that the language in 300.3(B)(3) would permit it anywhere you want to use it. Don Ganiere
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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

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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