art.334.80

[gerry]

What is the best approach for running romex beyond ten feet within an attic space using temp.factors.Do I quess how hot it may be on a given day or is there a set number to use or just don't worry about it.[location is new jersey]Thanks

#14 and #12 NM is already derated. What size is your NM? You have to derate if you bundle NM, but again #14 and #12 are already derated.

[gerry]

thanks for the reply awwt but I thought this art. was for temperatures over 86F.

[tom baker]

NM cable is derated from the 90 deg C rating, but can not be operated above the 60 deg C rating after final adjustment for temp or bundling.

AWWT: "#14 and #12 NM is already derated". I am not sure what you mean by this. Can you explain?

[ryan_618]

Doing the math on 14 12 AWG, I can't see ampacity adjustment being an issue until the ambient temparature exceeds 140 degrees, F. That is, unless you have to adjust ampacity for bundling in addition to ambient temperature. :)

[bennie]

What is the ampacity of 500 kcmil TW, at 132 degrees F. ambient?

[ May 10, 2004, 11:17 PM: Message edited by: bennie ]

Modern NM is 90C, but you cannot use 90C rating for ampacity. At 90C they could take more amperage, but it's derated automatically off the top.

[electricman2]

What is the ampacity of 500 kcmil TW, at 132 degrees F. ambient? 0 Amps :D

[brentp]

That's a pretty slick question Bennie! ;)