National Electrical Installation Standards

Standards as High as Your Own

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  • January 1, 0001

    In a new house construction project, can the electrical panel be in a floored attic if the installation meets all minimum set backs, and has access by pull down stairs? What code sections would apply? Eileen Felton
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  • January 20, 2020

    What is the maximum voltage drop for any branch circuit installed in a sensitive electronic equipment panel board? -Timothy Hardt
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  • January 21, 2020

    Is THWN conductor insulation suitable for use for the branch circuits for an operating room that is supplied by an isolated power system? Anthony Goode
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  • January 23, 2020

    Thank you for providing this service! I have an ungrounded three-phase 480-volt delta system and was wondering what the phase-to-ground voltage is. Hopefully you can provide some clarification. Not sure if the NEC addresses this situation. Kenneth McQuaid
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  • January 22, 2020

    Can a panelboard be installed on its back in the face up position? The NEC does not seem to address this orientation. Any guidance would be very appreciated. Thomas Dye
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  • January 17, 2020

    Gentlemen, I’m hoping you can help with an opinion. As you seem to understand how to apply the NEC rules from a practical viewpoint. Section 230.72 indicates the two to six service disconnects permitted in Section 230.71 must be grouped. There is no maximum distance on between the two to six disconnects, so how far is too far before the installation would not meet the grouping requirement. Could signage be installed to assist in meeting the grouping requirement? Any opinions would be very appreciated. Mark Taylor
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  • January 16, 2020

    Can electrical metallic tubing (EMT) be installed to supply a fire pump. The installation would be from the load side of the fire pump controller overhead on a ceiling of the fire pump room and then a vertical drop of the ceiling to the motor. There would be a transition from EMT to liquid-tight flexible metal conduit within 2 feet of the motor terminal housing. Job specifications are calling for rigid metal conduit. Thanks for any Code view on this, Mike Long
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  • January 15, 2020

    My husband is installing landscape lighting in our front yard and he is trying to determine how deep to bury the underground wires. Any guidelines would be so appreciated. Mary Christianson
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  • January 14, 2020

    What is the minimum size branch circuit conductor for a 50 HP, 3-phase, 460-volt motor that runs continuous and is installed in a steady ambient temperature of 85-90 degrees F? Our office is having a debate about this and we were hoping your forum could provide another view/opinion. Thomas Clark
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  • January 13, 2020

    If I used a length of 1-inch aluminum rigid conduit (10-foot sleeve) for physical protection of a grounding electrode conductor installed on a wall, is bonding required from the contained grounding electrode conductor to the conduit at both ends where the conductor enters the sleeve and where it exits? Thanks for any clarification you can provide. Alex Holtz
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  • January 10, 2020

    Does all electrical equipment have to be UL approved? Mark Goldberg
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  • January 9, 2020

    Does the NEC have a requirement for oxidation inhibitors for connections involving aluminum conductors?Alan Hunt
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  • January 8, 2020

    Can a fuse be installed for the grounded conductor of a circuit? Jordan Casey
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  • January 7, 2020

    In a hospital operating room, which ungrounded conductor supplied by an isolated power system can connect to the grounded conductor terminal of a 125-volt, 15- or 20-ampere, single-phase receptacle? Thanks for the insights provided through the Code Question of the Day. Travis Tripp
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  • January 6, 2020

    Thanks for providing this NEC Code question forum. Can a grounded conductor such as a neutral, be connected to a device on a terminal other than the terminal identified for the grounded conductor? Sammy
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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 recognized NEC® expert and author. He served on several NEC technical committees and is past chairman of CMP-12. In 2006, Charlie was awarded NECA’s prestigious Coggeshall Award for outstanding contributions to the electrical contracting industry, codes and standards development and technical training. NECA continues to provide this public forum in memory and recognition of all his fine contributions that has made 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.

NECA SAFETY PRODUCTS & PUBLICATIONS: NECA produces electrical safety publications and products for the industry including jobsite safety guides, handbooks and resource kits. View a full listing of available resources and products »

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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