National Electrical Installation Standards

Standards as High as Your Own

Friday, July 19, 2019


Hello all, I have a new storage building at a local high school being fed from an existing panel in the school. The engineer had me pull a grounding conductor in with the feeders, but my inspector is saying I need to bond my neutral at the disconnect for the new building.... my take is that the neutral is already bonded at the main switchgear for the school and bonding the neutral again would cause the grounding conductor to be a parallel run with the neutral back to the panel the building is fed from (not the switchgear). For this on whether or not the neutral should be bonded at the new building and if so, should I eliminate the ground I pulled in with the feeders...

Fyi the service is  225A 480/277V 3 phase 4 wire, not that that should change anything.

Thank you,

Jeremy Buxman


Hey Jeremy thanks for your question. An equipment grounding conductor you installed is required as stated in the first sentence of 250.32(B)(1). The last sentence of 250.32(B)(1) prohibits connecting a grounded conductor (neutral conductor in your example) to the equipment grounding conductor. Connecting the grounded conductor to the equipment grounding conductor would create a parallel path for normal current as you mention and also violate 250.24(A)(5). Show those sections to your inspector.

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.

NECA STANDARDS: NECA publishes the National Electrical Installation Standards™ (NEIS™), a series of ANSI-approved performance and quality standards for electrical construction. Visit for more information. NEISÔ can be purchased in three formats: as paper books, on CD, or as electronic downloads.

NECA SAFETY PRODUCTS: NECA publishes valuable electrical safety books and CDs for the industry. Visit to view or purchase NECA safety products.

 CONTACT US: To submit a Code question, subscribe, or unsubscribe from this list, please e-mail: