National Electrical Installation Standards

Standards as High as Your Own

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Monday, June 13, 2022

Question:

Dear CQD, Re CQD 5-20-22 on bonding requirements for metal members that are interconnected to form a building frame. The 05-20-22 question and your response was as folllows: 

"Good Afternoon,
 
During a recent inspection of our building under construction, the inspector said that the building steel had to be bonded. Our question is in wood-framed buildings with metal studs used inside the building and/or isolated metal studs or steel beams, does the steel need to be bonded and grounded?
 

Robert Miller

Hello Robert, Thanks for the question. First, the authority having jurisdiction has the interpretation and approving responsibility as indicated in Section 90.4. That said, based on the information in the question, we offer the following response. There are no requirements in the NEC to bond metal studs or remote steel materials to the electric supply source. Section 250.4(A)(4) requires electrically conductive materials that are likely to become energized to be connected together and to the electric supply source in a manner that establishes an effective ground-fault current path. Unless there is some substantiation that these metal materials are likely to become energized it is not necessary to connect them to establish an effective ground-fault path. The requirement for bonding exposed metal building framing applies when interconnected metal framing and structural metal are bonded together to form an entire building frame as indicated in 250.104(C)."     

Your answer is spot on, I would add that the specifications for the project may also require bonding of the metal studs as I have run into this on occasion. Mostly in operating rooms of hospitals, but I have seen it elsewhere also. Carefully reading the specs and getting clarification from the local AHJ can save us from huge problems later! Don't know how I would know that...David Fleming

A

Answer:

Hello David,

Thanks for the comments and the additional information. Yes, many jurisdictions have local or administrative rules that render project specifications and plans as applicable and must be followed, unless otherwise modified through permission of the applicable professional, owner, engineer, or other. Your example was a good one and additional bonding related to isolated power systems installed for operating rooms could be required by not only the specifications but also by the manufacturer's installation instructions for such systems. It's always a good idea to involve the inspection authorities since they have interpretation and approval responsibility as indicated in Section 90.4.

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