National Electrical Installation Standards

Standards as High as Your Own

Monday, April 9, 2018



I read your Code Question of the Day nearly every day and learn much about how the code is interpreted. Now I have a question which has not been discussed so far and is something which may be a future compliance problem with LED lighting and would like your take on it.

In a site inspection where new LED surface mounted fixtures were specified, the electrical contractor noted he would need to punch a larger hole in the back of the fixture so wiring within the outlet box would be accessible.  Per Article 410.24 (B) the box itself would is not the only means of support so he was correct.  He also noted this would be fine with a fluorescent (Electric-Discharge) fixture and is normal practice as they have ballast cavities running end to end, but LED’s elements are often only fed from one end and don’t need a channel.  The manufacturers installation instructions show the wire pigtails coming out of the outlet box to the fixture through a rounded edge ¾” wiring opening and show wiring connections made within a small protective cover adjacent to the LED driver.  If a hole large enough to allow access to the outlet box was punched into this particular fixture there is room between the 2 linear LED elements, this larger hole will remove the grounding screw along with the means to secure the provided wireway cover.  This modification of the light body may violate the manufacturer’s instructions so probably the warranty as well.  Without the wireway cover, the wiring would then be exposed within the light with nothing to enclose them so the contractor will then have to push the wire and wire nuts back into the box so they are not visible within the body of the light.  These instructions are from a very reputable lighting manufacturer and would seem reasonable since all the wiring connections would be made outside of the box within the light fixture wiring cavity and would be nothing in the box which needs access once the light is installed.  (I have included this page for you to reference.) Has the manufacturer created these instructions with an obvious code violation? With LED’s becoming the normal light fixture type, they are getting narrower where especially in strip lights the fixture body is often not as wide as an outlet box and placement of the LED element arrays are not always laid out where compliance with 410.24 (B) may become more difficult if not impossible.  Do you know of any exceptions available within the code which would allow the manufactures instructions to be used and produce a complaint installation?  Look forward to your response.

Donald (Don) Hopkins PE, FPE



Hey Don thanks for your question, it is an interesting one, and we are glad you enjoy the CQD. The instruction page you provided includes directions for supporting the luminaire independently of an outlet box which is covered by 410.24(A). The instructions also indicate that the luminaire is intended to be connected to a listed junction box and the illustration shows the supply wiring entering the luminaire though the hole you state to be 3/4 inch in size. That does not seem to comply with the wording in 410.24(B) as you mentioned. Luminaires must be listed as stated in 410.6 and those with exposed metal parts must be provided with a means to connect an equipment grounding conductor as stated in 410.46. Punching a larger hole that removes the equipment grounding screw and cover mounting screw does not seem like the correct solution. Contact the manufacturer and ask them how they intend compliance with 410.24 and the testing laboratory if necessary. Let us know what response you receive because you are correct it appears to be a problem. Possibly some one from Underwriters Laboratories will comment on the product standard requirements.

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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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