National Electrical Installation Standards

Standards as High as Your Own

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  • April 24, 2017

    Per NEC 430.122, what is the reason for the requirement to size the wire to the input current rating of a drive? For an analogy you don’t have to size the wire for a NEMA Size 1 full voltage starter for the current rating of the starter. Thanks, Kevin Therne
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  • April 21, 2017

    Code restrictions for closest lighting. My question is I have two short and narrow closets in a residential house, single family residents. That I have roughed in for one LED globed light fixture in each closest. Since both fixtures are L E D light fixtures with globes are there any code restrictions on this application. Marshall Putnam
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  • April 20, 2017

    What is the correct way to bond the neutral in a residential main circuit breaker panel. I have always ran the ground wire to the street side of the water meter & jumpered across the meter & connected to the neutral bar. I have also seen the ground connected to the closest cold water pipe & the water meter jumpered .the code isn't very clear on this, which way is correct. Is it also necessary to jumper the hot & cold water piping at the water heater? Keep up the good work, thanks Jim Jablonski
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  • April 19, 2017

    Are GFCI's still required under the 2017 NEC? The AF says no but it looks to me they are (422.5) Robert Schoenberg
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  • April 18, 2017

    Re: CQD answer published Monday, April 10, 2017 -Box Extension FPN- if you do use the extension to pipe in/out, other than when bringing the box” out of the wall”, & I have to get into the back box to do maintenance, ect, just know I will be making your ears as red as Santa’s nose. Fighting this kind of install is my number 1 pet peeve. John Dennis
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  • April 17, 2017

    What height does a subpanel need to be mounted in an ADA accessible unit? Jeff Lawrence
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  • April 14, 2017

    I need to install 110V and 208V electrical cord drops to equipment. The cords will drop roughly 14 feet from the wireway. We will be installing strain reliefs at the top. I need to know if I need to use a certain type of cord rather than typical SO type cord and if I'll need additional mid-run strain reliefs. Mark Morlan
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  • April 13, 2017

    I had a salesman show me a new UL listed product called Slicknut yesterday that is a grounding bushing/Locknut in one. It seemed to be a very good product…but I have a concern: If we use this U.L. listed product on any other Manufacturer’s EMT connector rather than the Locknut that is provided and listed for use with that EMT connector. Am I following the new listed requirements of the 2017 NEC? Similar Question, If I use one manufacturer’s cable… let’s say MC Cable can I use any manufacturer’s UL listed MC connector, even though it was not specifically listed for use on that manufacture’s cable? Thanks, Kelly Wofford
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  • April 12, 2017

    Is there a standard or code regarding the need for shatter proof light bulbs inside a manufacturing facility that does not deal with food or food products? Chris Moulton
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  • April 11, 2017

    Are smoke and monoxide detectors required in commercial buildings? Maurice House
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  • April 10, 2017

    With all of the alternative power sources available now can a house have D.C. Power for lights and controls? Kevin
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  • April 7, 2017

    Can you pipe or flex out of a four square box extension? David Alday
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  • April 6, 2017

    Re: CQD answer published Friday, March 31, 2017 - I have a reply for the March 30th Thursday question. All the work electric described sounded fine and code compliant. As for the question: "Is Romex ever allowed in any pipe of any kind?" The answer would be yes and you can usually choose your raceway. It's mentioned in more than one place in the code. A few would be 300.15, 312.5C, and 334.15. Mr.Lynes mentioned outdoor receptacles also. He did not say anything about routing to a box with NMB within a raceway outdoors. So his installation is still ok. NMB is not permitted in an outdoor, below ground or above ground, raceway. 300.5B and 300.9 tell us these raceways are considered wet locations inside and out. The conductors in those raceways must be a 310.10C wet location rated conductor. Here's what I think gets missed often - 300.5B and 300.9 tell us the raceways (inside and out) are considered wet locations. It does not say junction boxes. 314.15 tells us to use a wet location rated box in a wet location but it does not say the interior of those J boxes are to be considered wet locations. Interesting because you're permitted to put a 1/8" to 1/4'' hole for drainage in those boxes. So, it is permissible to enter the back of of an outdoor located J box with NM from an indoor location. The violation doesn't occur until you take off from that outdoor located J box with an outdoor raceway that contains conductors not rated for that wet location. Norm Feck
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  • April 5, 2017

    Re: CQD answer published Thursday, March 30, 2017 - Equipotential Bonding 2 Comment on: CQD answer published Wednesday, March 22, 2017 - Equipotential Bonding Loss of the neutral can be very troubling indeed. You're right in that symptoms will manifest themselves in various unexpected ways. The NEC is not perfect and not a preferred design manual nor for maintainability, but a minimum safety/performance code. If concern for loss of neutral connection is high, there are means to add detection equipment which exceed the NEC's minimum requirement. Most losses of connection (loss of neutral connection) are due to faulty terminations. The cause of most failures is failure to comply with 110.3(b) torque specifications. The issue it excessive torque, with lesser insufficient torque. A calibrated torque wrench needs to be used to comply. How many electricians have, much less, use them? When we find ourselves at the bottom of deep hole, the first thing is to stop digging it deeper. Best Regards, Nick Abbatiello
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  • April 4, 2017

    Question I have been using the above table for a project regarding use of 4/0 DLO cable in an open air setting so we can get a 405 Amp rating. We cannot find a perfect definition of "free air" anywhere in the code and a lot of information online contradicts itself. For a three phase system, can we stack a set of 3 cables in a triangular fashion, and keep a distance of the diameter of a cable between sets, and keep the rating of 405 amps? Where does the open air rating end? The code specifies for 4+ conductors needing derating, but with only 3 conductors should we expect any drop? Niko Panagiotakopoulos
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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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