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.

Multiwire Branch Circuit [210.4]

The content below is extracted from Mike Holt's Understanding the National Electrical Code, Volume 1, based on the 2020 NEC.

Section 210.4 of the NEC addresses Multiwire Branch Circuits, and the four first level subdivisions (A)-(D) list the rules that must be followed when installing this type of electrical circuit. There are serious hazards involved when these circuits are improperly installed. Are you familiar with the rules for installing multiwire branch circuits? Do you understand why these rules make sense?

When weighed against the hazards inherent with multiwire branch circuits, one can see how these rules are designed to prevent such hazards. Knowing the ‘how’ and the ‘why’ these circuits need to be installed the way they are helps to make sense of why these rules exist. So, read the attached text and study the graphics and by all means, be sure to watch the video as myself and a panel of experts take an in depth look at multiwire branch circuits.

Click here or on the thumbnail to the left to view or download the PDF of this Article to follow as you watch the video (3 pages, 735KB).

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 from Mike Holt's Illustrated Guide to Understanding the National Electrical Code, Volume 1, based on the 2020 NEC Program.

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Mike Holt Enterprises, 3604 Parkway Boulevard, Ste 3, Leesburg, FL 34748
"... as for me and my house, we will serve the Lord" [Joshua 24:15]

  • There was a recent article in CE Pro “How to properly protect Precious Tech” It dealt with Grounding and Bonding for high end low voltage systems. A reference was made concerning the Lighting control system NOT connected to the Electrical ground ring. It is my understanding that there should be only one point of grounding. Having two as stated would cause a difference of potential between the two. My question am I wrong in my thinking or is the article in error.

    Tom  January 19 2021, 1:06 am EST
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