You can still browse the site but some services may not work properly. This site requires Google Chrome, Firefox, Safari or Internet Explorer 10 and above. For mobile devices use an HTML5 capable browser.Download Chrome
In Part 1, we broke down the long sentence in the first paragraph of 430.62(A) to make it comprehensible. But there’s a second sentence and there are two exceptions. The requirements also continue in 430.62(B) and 430.63.
What else must you contend with when sizing the OCPD that protects motor feeders?
The second sentence of 430.62(A) says to consider one of the OCPDs to be the largest, even if two or more are the same rating or setting, when making the calculation required by the first sentence.
Now, what about those exceptions?
It’s worthwhile to review Informative Annex D, Example D8.
You can base the rating or setting of the feeder OCPD on the ampacity of the feeder conductors, if the ampacity of those conductors exceeds what’s required by 430.24 [430.62(B)].
What if a feeder supplies other loads, not just the motor load? In that case, the feeder OCPD must have a rating of at least the sum of the other loads plus 430.63] the rating permitted by:
The exception to the above applies to feeders that supply an MCC. In that case, follow the requirements of 430.94.