National Electrical Installation Standards

Standards as High as Your Own

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  • December 4, 2019

    Re: CQD answer published Monday, November 25, 2019 -Warning Ribbon for Underground Service Conductors Question regarding the Warning tape over HDPE. We are on a project now. They are doing horizontal boring to install feeders to carports that supply the AC to inverters. With horizontal boring there is no way to install warning tape. How is this addressed? It there an exception? Vern Detweiler
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  • December 5, 2019

    Re: CQD answer published Wednesday, November 27, 2019 - 2020 NEC Emergency Disconnects 1) AGREE with KEN.. it’s a Stupid idea some engineer came up with brought it to other engineers and over thought the process and added it to the 2020 code. WE ALL Still have time to voice out public objections on the 2020 NEC Bill Schell 2) "The concerns you express about burglary and mischief can be dealt with by locating the disconnecting means outside and locking it in the on position but locating the panelboard inside the building. The really evil people will find a way to defeat everything. The benefit to having the disconnecting means outside is for emergency responders so they can deenergize the interior wiring before entering the building." If it's locked in the on position, how do 1st responders deenergize it? Dave 3) Thanks for all your hardwork keeping us all on track. The poster that responded to the Nov 8 discussion on placing of breaker boxes on the exterior may be failing to understand what I believe to be the best reason to do so. The main breaker being accessible from the exterior favors when the fire department is dispatched to the building. First thing they do is to shut power down for safety reasons that I don't think needs to be explained. As you said, those "bad guys" will access a panel if they are in or outside the building if there intent is to disconnect security. Happy Thanksgiving to all! Jeff Frishof
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  • November 29, 2019

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  • November 28, 2019

    Min size conductor in a commercial branch circuit under 600 volts Vince Tomasino
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  • November 27, 2019

    Replacing HW and CW lines with PEX. Electrical Panel is grounded to existing CW line which is now discontinued. What is the proper method to now ground the panel?Franklin Dysthe
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  • November 26, 2019

    Re: CQD answer published Friday, November 8, 2019 -Outdoor Electric Equipment Hello, I have copied here the new code suggestion for outside disconnects: "There is a new 230.85 in the 2020 NEC for one and two family dwelling units that requires a disconnecting means to be installed outdoors at a readily accessible location so we will be seeing more equipment located outdoors in the future." It seems to me, you have stated the primary reason that this is a real bad idea because of the temperature extremes that equipment will have to endure. How about this one: It will give thieves an ideal way to probably prevent security systems from reporting the break-in in progress. It will present an ideal way to harass a neighbor or to make a prank on someone in the area by less than evil kids. I know it is a prime consideration by most people not to have a large ugly piece of electrical gear hanging on their house. That is a stupid idea to force everyone to have a disconnect on the outside of their home and especially in the snow belt where we have extreme temperatures.Ken Lynes
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  • November 25, 2019

    Can you use SO Cord outside? If you can't is there a Type that you can use?John Adams
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  • November 22, 2019

    Is the use of caution tape a requirement when trenching a fiber optic cable and placing it in HDPE conduit?Yvette Harrison
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  • November 21, 2019

    Can you feed a receptacle on the outside of the garage wall off the load side of gfci that is in the garage?Boyd Lamb
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  • November 20, 2019

    In a commercial setting, does an electrical panel have to be locked? What is the code and where can I get a copy of that code?Phil Collins
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  • November 19, 2019

    Outside at weather heads I typically see what is called an H-tap type of splice, where conductor transition from overhead outside wiring to a raceway or other chapter 3 wiring methods. I've been looking for a code rule that allows this type of splice without using a junction box, can you help me out Charlie? Thanks in advance for what you do each day.Chloe R.
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  • November 18, 2019

    The answer to last Monday's question did not get published on Tuesday November 12 so we are republishing it. I have a stepdown transformer 480V-120V. Usually for single phase, 120 Volts is line to neutral, is there any code violation per NEC 250.26 if the connection is 120 Volts line to line, both conductors are ungrounded? Jesus Santos
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  • November 15, 2019

    Charlie, Our apprenticeship class is discussing the following: 358.26 (EMT) states “there shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points (this is also stated in other articles)…..My question is whether a 180 degree bend would be acceptable as part of the total 360 degrees. Some in the class say the code is not prohibiting the 180 degree bend, others feel that 90 degrees would be the implied maximum for any bend. We would appreciate your input.Sal Genovesi
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  • November 14, 2019

    My furnace in the house I had just bought froze and split, also bursting many pipes and the heating system.(FHW) The plumber doing the repairs says,(he is a licensed electrician as well), that if he does the work to connect the new furnace electrical work, he needs to replace the corroded and moldy entrance box and breakers. The insurance company says he can connect it up just fine without changing any of it. Who is correct? I really need to get the job rolling, but this question among others has held us up for 18 months. HELP!! Mick Tufts
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  • November 13, 2019

    Re: CQD answer published Wednesday, November 6, 2019 - Emergency circuits 1) Totally disagree with Tuesdays answer. the circuits are kept separate but may run the entire length of a row of lighting picking up the EM ballasts drops. He did not say they were Emergency Backed up circuits off a Standby generator which must be separated. Bill Schell2) Good morning and thank you for your great work assisting by brother and sister electricians in the industry. Regarding the emergency wiring in the fixtures with the regular lighting circuit and beg to differ with your answer. It seems from 700.10 that the restriction is when the emergency power is from an "emergency source, or emergency distribution overcurrent protection." An emergency source would be a generator or battery back-up pack remote from the emergency light. However, when the power feeding the emergency ballast is also the circuit that feeds the lighting circuit then this would not fit the restriction of 700.10(B). All the best, Jeff Glanstein
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ABOUT CQD: The Code Question of the Day (CQD) is NECA and ELECTRICAL CONTRACTOR Magazine’s flagship National Electrical Code (NEC®) public forum for the industry, sponsored by EATON. The daily distribution of Q&A generates a lively dialogue and shares relative Code-based practical responses.

SUBMIT YOUR CODE QUESTION: Click here to submit a question to for inclusion in an upcoming edition of the Code Question of the Day, or email

CHARLIE TROUT: 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. Even though Charlie passed away in October of 2015, his work continues in spirit. NECA continues to maintain this question forum for its many subscribers in memory and recognition of all his significant contributions to making the NEC what it is today.

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IMPORTANT NOTICE: Unless the question requests a response based on a specific edition, all answers are based on the latest edition of NFPA 70® National Electrical Code®.

This correspondence is not a formal interpretation of the NEC® and any responses expressed to the questions are opinions and do not necessarily represent the official position of NECA, NFPA, the NEC Correlating Committee any Code-making panel or other electrical technical committee. In addition, this correspondence is neither intended, nor should it be relied upon, to provide professional consultation or services. 

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