Mike Holt Enterprises Understanding the NEC

Keeping up with the requirements of the Code should be the goal of everyone involved in the electrical industry. 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.

Feeder and Service Conductor Size [Table 310.12]

The content below is extracted from Mike Holt's Electrical Exam Preparation textbook, based on the 2020 NEC

Click here or on the thumbnail to the left to view or download the PDF of this rule. (4 pages, 1.2 MB)

Click on the image above to watch the video

Dwelling unit service conductors supplied by a single-phase, 120/240V system and feeders conductors supplied by a 120/240V or 208Y/120V systems can be sized using Table 310.12. The Table allows you to install a smaller size conductor which saves on material cost and on labor.

Here are a few rules that need to be considered when using Table 310.12 to take advantage of this table.

  • The service and or feeder conductors need to supply the entire load associated with the dwelling unit. [310.12(A) and (B)]
  • Feeder conductors do not have to be sized greater than the service conductors. [310.12(C)]
  • The neutral conductor does not have to be the same size as the phase conductors. [310.12(D)]

Take some time to read the attached text then join Mike and a panel of Code experts on this video as they discuss each of these rules!

• • •

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 Electrical Exam Preparation, based on the 2020 NEC Program.


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888.NEC.CODE (632.2633) www.MikeHolt.com
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]

Comments
  • The neutral with a 3-wire feeder from a 208Y/120 volt system is not permitted to be smaller than the ungrounded conductors, correct?

    Phil  January 18 2022, 12:26 am EST
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