National Electrical Installation Standards

Standards as High as Your Own

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  • August 8, 2017

    Hello, I'm glad Charlie's legacy lives on as I too enjoy starting my day with CQD. I recently was failed on a "service" inspection because the #6 AWG to the rods I used was covered in white insulation. My answer to the inspector was the NEC ,only says the conductor "shall be solid or stranded,insulated,covered,or bare" Am I wrong ? Thx, Eddie
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  • August 7, 2017

    Low Voltage junction boxes on the ceiling, do they need to have covers on them? The wire isn't in conduit either. I am in Minnesota Jerry Newton
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  • August 4, 2017

    My son called me with a code question this morning. It is a good question with a easy answer. However, many electricians would hesitate and answer wrongly if they didn't look at the exact wording in the code book. For this reason I am presenting the question to you and your readers. Mike's question: In front of an electrical panel can there be a floor drain within 36" of the front of the electrical service equipment and within the 30" width space? My answer was "The wording for the measurement of the working space is from 'the floor' and by definition a floor drain is "in the floor" and therefore outside of the restricted area. Seems strange that the low point in a floor would be so close to the electrical equipment, allowing the flow of water to run towards the electrical equipment, but that is how I read the code. Might be a good suggestion to add wording to the code so as to prevent the slope of the floor to end at an electrical working space. Reasoning is that such a situation would cause a dangerous pooling around electrical equipment. Adding a floor drain would remedy the situation but that would be an exception, since the electrical code normally can't make an obligation on a plumbing ordinance. A good example where "depth" does not mean "a measurement deep in the floor." All the best, Jeff Glanstein,
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  • August 3, 2017

    Please keep up the good work. UF cable; what column of the table 300.5 would you use for residential? Column 1 is what I say 18 inches below grade. But Column 4 shows 12 inches if GFCI protected and 20 amp circuit or less. Please explain. Thanks, Brett Howard
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  • August 2, 2017

    When you run the number 8 bare copper around the pool does it have to be 18 to 24 inches away from the pool and 8 inches deep in the ground in lieu of just laying around the pool and covers with dirt and stone? Thanks, Joe
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  • August 1, 2017

    On a 1200 amp 480/277, no main, with a six disconnect rule, do each disconnect if under 1000 amp, do I need them to GFI? Mike Koch
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  • July 31, 2017

    Hello, I am interested in getting answers about load calculations for car chargers I see that in the NEC 625.14 is missing.... I have read that was a misprint and 625.41 is the correct references code, the aforementioned section only seems to refer to the equipment supplying the load it does not seem to contain calculation requirements just seems to indicate a rating of continuous.. My question is in regards to feeder and service calculations when adding loads to serve car chargers what demand factors can be applied for standard or optional calculations. As far as I can tell from reading the NEC there is no specific section referencing this. Thank you and I appreciate any help Oliver Allen
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  • July 28, 2017

    Rule 250.122 (B) says "Where ungrounded conductors are increased in size from the minimum size that has sufficient ampacity for the intended installation, wire-type equipment grounding conductors, where installed, shall be increased in size proportionately...". What defines "the minimum size"? For example, (using values for copper from 75° C column of T310.15 (B) (16) and assuming no factoring is required), 600 kcmil is frequently used. But parallel # 3/0 (167.8 kcmil) could also be used (obviously with paralleled EGCs). Using this option, is the minimum size to be considered 335.6 kcmil? John Duggan
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  • July 27, 2017

    Table 250.122 requires that a copper equipment grounding conductor for a 5000A feeder must be 700 kcmil (assuming no other rules require increase). Is it permissible to use 2 – 350 kcmil conductors instead? If it is acceptable, what rule supports this? John Duggan
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  • July 26, 2017

    Re: CQD answer published Wednesday, July 19, 2017 - Torqueing Terminations As published: “ It might be good to use those values in the absence of specific manufacturer's instructions but it is specifically required.” Or, is this correct? “. It might be good to use those values in the absence of specific manufacturer's instructions but it is NOT specifically required.” Thanks for a valuable service. Cordially, William H. (Bill) Hudson, CBO, MCP
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  • July 25, 2017

    Exemption for Agricultural Bldg. Bldg is to be used for hay storage and maintenance of farm equipment. Can I set a 200a panel with a meter? Wiring to method to be UF Joel Hendren
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  • July 24, 2017

    Good Afternoon, Thank you very much for your Code Question of the Day feature. It is a much appreciated service, especially for those new to the trade, like myself. My question is in regard to the use of zip ties in a panel to group "hot" conductors, neutral conductors, and bare equipment grounding conductors (as exemplified in the attached image from a school project: a sample residential service panel). My understanding is that the following three code sections would apply: Section 110.12 "Electrical equipment shall be installed in a neat and workmanlike manner." (I figure this is why we're using these zip ties in the first place, along with professional pride.) Section 310.15(B)(3)(a) "...where single conductors or multiconductor cables are installed without maintaining spacing for a continuous length longer than 600 mm (24 in.) and are not installed in raceways, the allowable ampacity of each conductor shall be reduced as shown in Table 310.15(B)(3)(a)." (So, my "hot" conductors in the image are rightly "un-bundled". My neutral conductors may be "bundled" for less than 24 inches, which they are, and my equipment grounding conductors, which shouldn't be carrying a load under normal circumstances, are nevertheless being called "conductors" and fall under the same rule, so less than 24 inches of "bundling" is OK) Section 334.80 "Where more than two NM cables containing two or more current carrying conductors are installed in contact with thermal insulation without maintaining spacing between the cables, the allowable ampacity of each conductor shall be adjusted in accordance with Table 310.15(B)(3)(a)". (So, here they are talking about "cables" which I understand to mean the group of conductors within the overall sheath, as opposed to bundled individual conductors coming out of multiple different sheaths. Nevertheless, the gist of this section would seem to indicate that if I have conductors in contact with each other's' thermal insulation, the allowable ampacity of each conductor must be adjusted according to the table. There is no mention in this section of the 24 inch limit.) Barring any other sections of The Code that I'm unaware of that call out this type of "bundling" in an installation I'm inclined to believe that the zip-tying as shown in the picture necessitates an ampacity adjustment according to Table 310.15(B)(3)(a). (Assuming I have no way to prevent the individual circuits from being simultaneously energized as is mentioned in the notes to that table). Is this a correct/reasonable interpretation of The Code or have I missed something? Thanks very much for your help, Matt
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  • July 21, 2017

    Disconection of out of service branch circuit wiring Is there a code requirement for the branch circuit wiring to be disconnected from the breaker or to turn off the breaker when a device such as a sign transformer is removed from the circuit? The end of the circuit is left in a junction box with capped wires. While it is safer to disconnect the wires or at the minimum turn off the breaker and label it, is there a requirement for such? G Floyd
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  • July 20, 2017

    Scenario: Need 150A of continuous loads 480ft away from an existing 200A 120/240v panel. If I were going to install / relocate a new panel / subpanel at the 480 ft distance, what size wire and OCPD would be required? What is the equation for figuring this out, and do I use the 120v or 240v for calculating voltage drop? Thank you, Kenny
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  • July 19, 2017

    Re: CQD answer published Tuesday, July 11, 2017 -LFNC Fittings I believe that Carlon has a solvent that is rated FNMC to PVC fittings. Sincerely, Dennis Moy
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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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