National Electrical Installation Standards

Standards as High as Your Own

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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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  • March 11, 2019

    Re: CQD answer published Monday, February 25, 2019 -Article 725 Class 2 Wiring 1) Hi Charlie: I'm taking an alternate view on the answer Chapter's 5, 7, 8, 9 in the NEC modify or amend the general rules in prior chapters. If you use a Chapter 3 covered raceway, then it must be installed and supported per the salient requirements since there's no mention of it under Article 725, Class 2 wiring. In fact, due diligence would extend to marking such raceway outlets stating that only Class 2 wiring is permitted. If metal raceways are used and part of the GEC, then all bonding and grounding is still required. The raceway needs to be intact as well. Often times, Class 2 wiring is wire-tied for support to other structures. This is a violation since wire-ties are not Listed for that purpose. Suitable straps, etc. are required and not supported from other electrical raceways, etc. Wire-ties or Tie-Wraps used outside of enclosures exposed to UV tend to get brittle and lose mechanical integrity. An example of labeling raceways to restricted type wiring can be found in Art. 504, Intrinsic Safety. The only place where you wouldn't is a Listed raceway section, such as a RMC stub, is used as a feed-though to facilitate ease of installation. Best Regards, Nick Abbatiello 2) I have been a long time viewer and a good friend of the Late Charlie Trout. He was a great person, miss seeing him and his Carole at the IAEI Western Section Meetings and I am happy to see that NECA is still carrying on his legacy. In the answer on Friday, February 22nd you referenced that there was no reference to Section 300.11 in 725.3. With Article 725 not modifying the requirements in chapter three it would appear the requirements for the raceway articles would apply. Article 725, the limited energy articles and the Chapter 8 cables usually do not require those cables to be in a raceway. It has been my thought that if a raceway is installed, than the requirements of that raceway article would apply. Thank you to NECA for continuing this valuable service. Dave
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  • March 8, 2019

    Can you build an outdoor residential service with a meter can and EMT riser through the roof and have it all rocked in. In other words, standing in front of the service all you would see is the enclosure door of the load center and the Meter face, everything else including the 2" riser conduit would be behind the rock. My thought is that you can't do that but I can't find any code in the NEC that supports that? Please e-Mail me. Clayton Walden
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  • March 7, 2019

    When a sub-panel is installed in a residential dwelling, can the grounding electrode conductor consist of the rigid conduit raceway or need it be run inside the raceway with the other conductors? Gwyneth Abell
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  • March 6, 2019

    240.4(B)(1): does this article restrict circuits with more than one receptacle outlet from using the next size breaker if the conductors are derated? Barry Yeslow
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  • March 5, 2019

    Dear CQD: Most of our manufacturing equipment is supplied by a 480V ungrounded delta system. The busways have only the three phase conductors, with no grounding conductor in the bus. The manufacturing equipment is "grounded" (?) by properly-sized equipment grounding conductors that are connected to field-installed ground lugs screwed to the metallic bus plug enclosures, using whatever type of machine screw and nut is handy (few of the bus plugs, if any, have a factory-installed grounding means in them). I don't know how the busway enclosure is grounded, but the bus plugs are clamped to the painted busway via painted clamps. Almost every machine comes from the build shop with a 120V duplex receptacle (sometimes GFCI protected), supplied by a 480V x 120V step-down transformer, and protected by a 10A or smaller OCPD (receptacle is intended for powering a programming terminal). The receptacle's ground wire AND grounded circuit conductor are both connected to the X2 of the transformer. In turn, the X2 of the transformer is connected to the backplane/enclosure of the manufacturing equipment. This is a very common arrangement is manufacturing plants. With regard to grounding and bonding, what code violations come to mind with this type of installation, for both the 480V and 120V circuits described, if any? Thanks, Wes Nichols
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  • March 4, 2019

    Apparently not everyone received last Thursdays CQD (February 28, 2019) therefore the answer to Wednesday's Question was not shared so we are re-publishing it today. Re: CQD answer published Thursday, February 14, 2019 - GFCI Location With regards to your answer on Feb 13th, how would this be different than having a receptacle in the ceiling for garage door openers? Would exception 2 to 404.8(a) apply? Bryan Berg
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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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