Derating conductors

[zeilzabob]

Can someone point me in the direction where the NEC allows to use the 90c column when derating conductors.

Thanks

 

[tom baker]

Start with 240.4
310.10
And then 110.14(c)(1)

If you really want to trip up one of your coworkers, ask then what the ampacity of 12 THHN AWG is. Its not 20 amps. Most get this wrong.
Even 14-2 NM is rated 25 amps, see 384.

 

[Dan coulstring]

Start with 240.4
310.10
And then 110.14(c)(1)

If you really want to trip up one of your coworkers, ask then what the ampacity of 12 THHN AWG is. Its not 20 amps. Most get this wrong.
Even 14-2 NM is rated 25 amps, see 384.

334.80 says the 60 Degree C column shall be used for NM cable ampacity ratings I know it is all in the way you ask the question

 

[infinity]

334.80 says the 60 Degree C column shall be used for NM cable ampacity ratings I know it is all in the way you ask the question

Yes, and for certain applications, A/C unit for example, you could use the 20 amp rating of #14 NM cable.