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

Registered: 03/31/04
Posts: 727
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?

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#214533 - 12/19/14 12:54 AM Re: derating rooftop conductors [Re: BigB]
Tesla Offline
Member

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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