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Ampacity Derating

Posted by johnsolar (My Page) on
Sun, Feb 28, 10 at 23:55

I'm trying to understand the cable OCPD relationship when it comes to derating the ampacity and therefore choosing the proper wire size and OCPD. In 310 there is a lot of jumping between columns i.e. 90 degree C to 75 degree to match the wire with the breaker. I understand the math but was hoping that someone could help with a simple "down and dirty" system to get through the derating equations. Thank you.

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RE: Ampacity Derating

There are books available that will provide the help you seek. Look for books by Joseph McPartland or Fredrick Hartwell. Used books will be fine as this is not a new topic by any means. is one source for such books.

Here is a link that might be useful: Look here

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