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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.
| EGC for Parallel Conductors, Sizing [250.122(F)] |
The content below is extracted from
Mike Holt's Understanding NEC Requirements for Bonding and Grounding, based on the 2020 NEC. Be sure to download the PDF to follow as you watch the video.
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Click here or on the thumbnail to the left to view or download the PDF of this rule. (4 pages, 1,238KB)
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Click on the image above to watch the video
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Even the simplest of the rules in Article 250 Grounding and Bonding have certain nuances that can make it complicated. Take for example 250.122(A) which tells us the size of an equipment grounding conductor is sized based on the circuit overcurrent protective device using Table 250.122. If you install a 1000A OCPD, you can check Table 250.122 and select a 2/0 AWG copper EGC. It doesn't get much easier than that! But what if you're paralleling that same 1000A in separate raceways? Does the size of the EGC change? Do you need more than one EGC? This is where even one of the simplest of rules can become one of the most complicated!
The minimum 1/0 AWG sizing requirement for parallel conductors in 310.10(G) does not apply to the equipment grounding conductor. If parallel sets of conductors are installed in multiple raceways or cables the EGC in each raceway or cable must be sized using Table 250.122 based on the circuit’s overcurrent protective device. Be cautious when installing cables in parallel, you will probably need to special order a cable with a larger than normal EGC in it.
Turn your hat around backwards as you join Mike and our panel of experts for this wild ride where they explain the rules for correctly sizing the EGC for parallel circuits and give you the information you need to correctly apply the NEC.
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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 Understanding NEC Requirements for Bonding and Grounding textbook, based on the 2020 NEC Program.
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