National Electrical Installation Standards

Standards as High as Your Own

Tuesday, September 7, 2021


Question: Comment on the e 8/3/2021 answer:  Monday, August 2, 2021


Monday's Question: Hello CQD, I have an 1 1/2 inch EMT with multiple branch circuits. can you run one oversized ground wire for all branch circuits and attach it to a ground bar in the 12x12 box that all the circuits run into.                                 

Monday's Answer: Hello Daniel, A single equipment grounding conductor can be installed with multiple circuits in the same single run of electrical metallic tubing (EMT). Section 250.118 recognizes that the EMT by itself can serve as the required equipment grounding conductor. An installed single equipment grounding conductor must be sized based on the rating of the overcurrent protective device ahead of the largest branch circuit in the run. See Section 250.122(C). Connecting the equipment grounding conductors together and to the box using an equipment grounding terminal bars one way of complying and this is covered in Section 250.148.

Comment: Some local codes do not allow for EMT conduit to be used as the ground conductor. Charles Murry 


Hello Charles,

Thanks for the additional comment on the response for the 08-03-2021 question and answer. The Code Question of the Day provides responses based on what is included as minimum requirements of the National Electrical Code. Your comment is a good one and provides a reminder for readers that there certainly could be local code requirements that are more restrictive than the minimum rules in the NEC. In those cases, legally adopted local electrical code rules would be applicable. 

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.

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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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