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#214531 - 12/18/14 07:28 PM derating rooftop conductors
BigB Offline

Registered: 03/31/04
Posts: 725
Loc: Tucson, AZ USA
When derating THWN-2 copper conductors for ambient that will eventually terminate in a sub panel with a 125 amp rating can I use the 90C column?

2014 / 2011 NEC & Related Books and Study Guides
#214533 - 12/19/14 12:54 AM Re: derating rooftop conductors [Re: BigB]
Tesla Offline

Registered: 06/16/04
Posts: 1280
Loc: Sacramento, CA
The sole and only reason for that column IS derating.

For there are no 90 degree rated devices out there.

One then uses the lesser computed ampacity limit.

So, yes, you start with the 90 degree column.


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