National Electrical Installation Standards

Standards as High as Your Own

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  • October 14, 2019

    Ok, lets try this, I have been through the codes with National Electrical Code Article 408.4 & NEC 110.22 and do not believe it answers my question. My question is: If a non-electrician is given a hand written panel schedule and retypes, doesn't some authority need to approve the update/changes before the new panel schedule is remounted in the panel? if so what code article state this approval process. I as a maintenance manager already have enough on the line for safety concerns. This means, someone else did the work on the panel labels but who "should" (need the code here) QC it or is responsible for the “An Approved Degree of Detail”, 408.4.Jim Perpinan
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  • October 11, 2019

    Thanks for providing the service of QCD, I look forward to reading it every morning. Is working space, required by NEC Article 110.26, required for existing service panel locations where the service is subject to being changed or upgraded to a new service panel but the existing locations "work space" has been infringed on over the years by water heaters, softeners, shelving, clothes closets built, etc.? Or does NEC 110.26 simply cover new construction installations?Thank You, Chris G.
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  • October 10, 2019

    Per 2017 NEC, is shared neutral conductor permitted in multiwire branch circuits to serve line-to-neutral loads for lighting and/or receptacles installed indoor? Section 200.4(B) states that "unless specifically permitted elsewhere in this Code". Specific requirements in sections 215.4 and 225.7 permit multiple circuits to have a common or shared neutral conductor.Jesus Santos
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  • October 9, 2019

    Re: CQD answer published Thursday, October 3, 2019 - Suspended Ceiling LuminairesAlong with this question. I have a question about the MC cable from troffer fixture to the next fixture. We were asked to mount a support wire for this MC cable independent from the ceiling supports. In the past we used the CADDY clips that were installed on the same wires that also support the ceiling "T" Bars. Our inspector is asking for separate wires to the ceiling for MC cable support. Most of the cables were 10'-12' long. The Suspended ceiling is 9' and the roof trusses are about 18'-20'. We know they are requiring the Earthquake Clips to secure the fixture to the "T"-Bars.Tom Inman
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  • October 8, 2019

    Hello, I’m trying to get clarification on section 310.15 about bundling MC. In my situation, I have many MC of different size (12-2,12-4, 12-6, 10-4) and I need to run them in 8 foot long emt chases across an exposed ceiling hallway. The only place they are run in a “bundle” will be in these 8’ chases (before and after the chase they are supported so they maintain spacing). My question is how many of these mc can I shove down a chase without having to derate. 20 current carrying conductors? Do I count the neutrals? Do I automatically have to derate since some of them will be 12-4 and bigger? Thanks in advance.Nik Carson
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  • October 7, 2019

    Can you inform Senator XXXX that increasing the size of a conduit does not affect the adjustment / derating factors of current carrying conductors in the conduit?Barry Yeslow
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  • October 4, 2019

    Can service conductors and load conductors be inside the same pull box or is that an NEC code violation? Aaron McClanahan
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  • October 3, 2019

    Good morning, Thank you for your continuing great work with this forum. We have a structure that previously was a Place of assembly, with a commercial kitchen. There are changes being made. The changes include removing the kitchen completely and the entire structure will be renovated to be a dormitory with some bathroom facilities. The proposed occupancy of the dormitory will be 106 persons. Is NM cable approved for the new installation? Jeff Glanstein
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  • October 2, 2019

    Hi, I know the troffers on grid must be affixed by wire to opposite corners and to ceiling. Do the wires have to be two independent separate wires or can one wire be looped - affixed to each corner and go up and be supported. So one or two completely separate wires per troffer to ceiling?Thank you Debra Rogers
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  • October 1, 2019

    The question (additional comments) published on September 25, did not have the correct answer included so we are republishing it. Maybe the gremlins removed it. Thanks to those readers who pointed that out.Re: CQD answer published Thursday, September 12, 2019 - Fence Grounding1) In reference to fence grounding at industrial facilities; if there are transmission lines nearby, running parallel to a long fence or pipe line, they can induce current into the fence or other metal structures. This current will seek a ground path in order to return to it's source. I have witnessed arcing between a non-grounded fence where it "almost" touches a grounded fence section. Daniel Cribbs2)I am not sure about his facility and the reasons, but there are several reasons for the grounding of the fences. My guess from his description is that it is probably for Lightning protection.A) Lightning arresting – Lightning can travel great distances in a metal fence if it is not grounded well. This could easily cause damage to people, structures or objects thousands of feet away from the strike.B) Posts that only go down two feet may be in earth that has too high of resistance to effectively ground against lightning. In few soils will two feet be enough for proper grounding. Earth resistance measurements will be required to specify the Grounding rod length. “Rule of thumb” in this case may be due to previous ground resistance measurements, but may not hold true for earth 1000’ away. It is not a safe bet that adding grounding rods every 50’ would provide the proper protection unless tested. Grounding testing should be done on a regular basis to maintain the integrity of the protection, typically once a year for building protection, but maybe less often for fencing as long as there is a regular visual inspection for loose connections, mower damage, etc.C) Metal fences around Medium and high voltage substations also require Grounding to prevent static and stray voltages from energizing the fence and have much greater Grounding requirements than that for lightning protection.Thank you, Ratib Baker, CMS, RCT
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  • September 27, 2019

    When installing IMC in direct contact with the earth do you need to add corrosion tape?Dirk Dube
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  • September 26, 2019

    How many outlets can I put on a standard 20A above counter small appliance above counter circuit?Gary Gendotti
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  • September 25, 2019

    Re: CQD answer published Thursday, September 12, 2019 - Fence Grounding1) In reference to fence grounding at industrial facilities; if there are transmission lines nearby, running parallel to a long fence or pipe line, they can induce current into the fence or other metal structures. This current will seek a ground path in order to return to it's source. I have witnessed arcing between a non-grounded fence where it "almost" touches a grounded fence section. Daniel Cribbs2)I am not sure about his facility and the reasons, but there are several reasons for the grounding of the fences. My guess from his description is that it is probably for Lightning protection.A) Lightning arresting – Lightning can travel great distances in a metal fence if it is not grounded well. This could easily cause damage to people, structures or objects thousands of feet away from the strike.B) Posts that only go down two feet may be in earth that has too high of resistance to effectively ground against lightning. In few soils will two feet be enough for proper grounding. Earth resistance measurements will be required to specify the Grounding rod length. “Rule of thumb” in this case may be due to previous ground resistance measurements, but may not hold true for earth 1000’ away. It is not a safe bet that adding grounding rods every 50’ would provide the proper protection unless tested. Grounding testing should be done on a regular basis to maintain the integrity of the protection, typically once a year for building protection, but maybe less often for fencing as long as there is a regular visual inspection for loose connections, mower damage, etc.C) Metal fences around Medium and high voltage substations also require Grounding to prevent static and stray voltages from energizing the fence and have much greater Grounding requirements than that for lightning protection.Thank you, Ratib Baker, CMS, RCT
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  • September 24, 2019

    I repaired an exterior main breaker falling of a home and when I opened the cover I observed a piece of 83 nm cable connected to the load side of the 200 amp breaker. The cable goes +-30 feet to the load luges of a pool equipment panel. How many code sections does instillation involve and what articles are they. This project was inspected in 2014 by the Myrtle Beach code compliance office and said it passed code.Denny Carr
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  • September 23, 2019

    Apparently not everyone received last Fridays CQD (September 20, 2019) therefore the answer to Thursday's Question was not shared so we are re-publishing it today.I have an installation where the grounding electrode conductor enclosure consist of both rigid metal conduit and PVC. Should each end of the rigid metal conduit (rigid 90s) be bonded. They have the threaded end where the wire exits the enclosure bonded, but not where the rigid changes to PVC. If so, how? I think I know, I just have a contractor that disagrees and I wanted to get your knowledgeable input to share with the contractor?Thanks, Lee
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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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