National Electrical Installation Standards

Standards as High as Your Own

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  • April 27, 2020

    Comment on Code Question of the Day for 04-08-2020. As always, I appreciate the insight you bring to code clarification. Keep up the good work. Response to this answer provided on 4/9/2020: The answer is no. The NEC does have multiple rules that require qualified persons which is defined in Article 100. Regulating the qualifications and certificates of contractors and electrical workers is beyond the scope of the NEC and is typically handled at the state or local jurisdictional level. The second part of this question is also a jurisdictional issue. Some jurisdictions exempt systems and installations of less than 50 volts from any permit or electrical inspections. The NEC does have rules that pertain to such systems. It's is always a good practice to verify the specific requirements regarding licensing with the local jurisdiction. I would like to add that certain systems that may fall below 50 volts such as: fire alarm systems, fire suppression systems, or fuel monitoring systems, that may fall under the jurisdiction of other codes, such as NFPA 72, and may be under jurisdiction of an authority other than the electrical inspector, such as the Fire Marshall. Depending on the state and local requirements, these types of installations may in fact require state licensure or certification and local permitting and approval for those engaged in that type of work. And as you clearly stated, it's always best to check with your local building department official to verify prior to commencing with the work. Vaughn Langless
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  • April 28, 2020

    Hello, My question is do conductors passing straight through a junction box need to be identified in that box ? Jeff Wright
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  • April 24, 2020

    I read the CQD every day. We've been having a debate about the number of receptacles in a duplex receptacle. I say two because there are two receptacles on a single mounting strap. Others I work with say it's one receptacle because it is on a single mounting strap. Can you clear up this for us? Thanks, Tim Simpson
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  • April 23, 2020

    Dear Code Question, If I have a 3-phase, 3-wire, corner grounded delta system, is there a rule in the Code for identification of the grounded phase? Thanks for any help you can provide. Ed Brink
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  • April 22, 2020

    Comment on the response to the Code Question of the Day on 03-24-2020. Thanks for the code question of the day. Great service. It is my understanding that the ground on any male plug cap is always the largest and longest prong. It goes in first and comes out last, so from eye level and below it should be ground up on the device and above eye level the ground should be down just for ease of use. If the devices are horizontal take your pick to orient the ground left or right. Once again thanks for the code question of the day. Frank Burdo
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  • April 21, 2020

    Hello, I am working in a lighting distribution on a new building, where I have 5 separate circuits with 10 lights per circuits. Can I run all the circuit using one conduit and using pull boxes to branch to different locations where the lights are. Thanks, Frank Hernandez
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  • April 20, 2020

    Good morning, Re: 2017 NEC Article 250.120(B) Can I get your interpretation on the last sentence of Article 250.120(B). It states that "aluminum or copper clad aluminum conductors shall not be terminated within 18" of the earth". In freestanding service equipment, the ground buss is located well below the 18" requirement and this equipment is UL listed. My interpretation is if the equipment is placed on an equipment pad then there is no NEC violation. Can you please provide an explanation. Thank you, Ed Tait Jr
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  • April 17, 2020

    Hi Charlie and Company, what is the minimum distance between conduit entries in a box for a feeder conduit running straight through the box, if the conduit is 4-inch, and it contains 4 - 600 kcmil copper conductors? I know this seems simple, but this issue came up in the shop last week and there were a variety of different answers. We just went over this in a Code class. Marla Simpson
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  • April 16, 2020

    I read the Code Question of the Day each morning. What is the hazardous area classification from a gas dispenser at a convenience store? Armond Ashton
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  • April 15, 2020

    Good morning Code Gurus, Is a box required at t splice in a temporary lighting circuit? Thanks in advance for any clarification you can provide. Mike Jason
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  • April 14, 2020

    Hello CQD, I enjoy the Code questions and responses each day with my morning coffee. Here is a question. Code Section 230.70(A)(1) indicates that the service disconnecting means must be located readily accessible and either outside of a building or structure or inside nearest the point of entrance of the service conductors.The inspector says no more than 10 feet is allowed inside a building. Where is that in the NEC? Timothy Grant
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  • April 13, 2020

    Greetings Code Question Staff, Can rigid metallic conduit be installed without a wire-type equipment grounding conductor installed with the circuit conductors in the conduit? We have a project specification that requires this. The project specs also indicate that compliance with the latest edition of the NEC is also necessary. We appreciate your insight. James Laughlin
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  • April 10, 2020

    Good Day, we are hoping you might provide some clarification about the NEC requirements for identification of the high-leg conductor installed in a 120/240 delta high-leg system. The utility says it needs to be red in color and the "C" phase is the high leg. What does the NEC say? Thanks for your help. Jerry Blair
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  • April 9, 2020

    SAFETY REMINDER: Today the Code Question of the Day offers an important safety reminder: Check the operation of all ground-fault circuit interrupter protective devices at least once per month. Replace any GFCI devices that are inoperative. If you are not trained to perform this work, hire a qualified contractor or person to perform these tasks.
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  • April 8, 2020

    I read the Code Question column every day. My question is simple, does the NEC require licensing of electrical workers and electrical contractors? What if the work is less than 50 volts? Adam Eastwood
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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.

NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. NEIS can be purchased in the NECA Store in three formats: a printed or PDF download of a standard or, as an annual subscription service.

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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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