Mike Holt Enterprises Understanding the NEC

Keeping up with the requirements of the Code should be the goal of everyone involved in electrical safety. The following is what I feel is an important rule in the 2020 NEC®, complete with graphics and a video. I encourage you to use it as a training resource for your organization, and share it with your colleagues.

Bonding, Metal Raceways [250.97]

The content below is extracted from Mike Holt's Understanding NEC Requirements for Bonding and Grounding, based on the 2020 NEC.

Article 250, in the General Requirements, [250.4(A)(3)] tells us that normally noncurrent-carrying conductive materials enclosing electrical conductors or equipment must be connected together (bonded) so that we establish an effective ground-fault current path. Of course, this would include metal raceways that terminate to metal enclosures which typically accomplishes this via the metal-to-metal contact that is naturally created. But what about where there are concentric or eccentric knockouts involved? Or better still, what about higher system voltages such as 277.480V? Are the rules the same? Are there other considerations in this case?

If your answer to any of these questions was, I'm not sure or, I just don't know then you should take the time to read the text, study the graphics, and watch this video in which we discuss the Code requirements [250.97] that address just such a scenario!

Click here or on the thumbnail to the left to view or download the PDF of this rule to follow as you watch the video. (2 pages, 330 KB)

Click on the image above to watch the video

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We'd love to hear from you about this series, and the ways you're using it. Send us your comments and feedback by clicking on "Post a Comment" below. Look out for the next part in this series a month from now, and please share with your colleagues.

 

This content is extracted fromĀ Mike Holt's Understanding NEC Requirements for Bonding and Grounding, based on the 2020 NECĀ Program.


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Mike Holt Enterprises, 3604 Parkway Boulevard, Ste 3, Leesburg, FL 34748
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Comments
  • The formula used in the graphic is I^2/R, not V^2xR or V^/R. Please watch the video again.

      January 12 2021, 5:59 pm EST

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