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derating rooftop conductors #214531
12/18/14 10:28 PM
12/18/14 10:28 PM
B
BigB  Online Content OP
Member
Joined: Mar 2004
Posts: 725
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?

2017 / 2014 NEC & Related Books and Study Guides
Re: derating rooftop conductors [Re: BigB] #214533
12/19/14 03:54 AM
12/19/14 03:54 AM
T
Tesla  Offline
Member
Joined: Jun 2004
Posts: 1,273
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.


Tesla

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