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NEC Quiz: Article 430 Answers, Part 5

by Mark Lamendola

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  1. They protect motor feeder conductors against overcurrents due to short circuits and grounds [430.61]. They do not protect against motor circuit overloads.

  2. The run-on sentence in 430.62(A) is incomprehensible and needs to be translated into English. That said, the gist of it is the rating or setting of the feeder OCPD can't exceed that of the branch circuit OCPD. This is counterintuitive, because we think of feeders as being larger than branch circuits. For a greater understanding of this rule, read 430.24 and see Informative Annex D, Example D8.

  3. Yes [430.61(B)], and that is how it would be done in a typical load side power distribution scheme. Again, read 430.24.
  4. Where a feeder supplies a motor load and other loads, the feeder OCPD must have a rating at least as much as the sum of the other loads plus three quantities. What are those three quantities?
  5. Is there an exception to the rule above? If so, what is it? If not, why isn't there one?