code ref for derating

Status
Not open for further replies.
Twoskinsoneman said:
Can't seem to find where is says you use the 90 degree column for derating purposes...lil help
Click to expand...

You derate from the column that the conductor is listed under. For instance, if you are derating THHW, you start with the number in the 75? column.

The entire process starts in 310.15(B)(2)(a), and the Table refers you to the values in T310.16.
 
Twoskinsoneman said:
Can't seem to find where is says you use the 90 degree column for derating purposes...lil help
Click to expand...


I think your looking for 110.14(C) Temperature Limitations. ......Conductors with temperature ratings higher than specified for terminations shall be permitted to be used for ampacity adjustment, correction, or both. (derating) ;) I feel they should at least reference that article from the 310.15 and 16 IMHO

I was actually looking for this earlier myself as well. Just remember that when derating that most breakers, lugs etc that you terminate to has ONLY a 75 degree rating, so after all the you derating your max amperage cannot go over the 75 degree column even though it says the wire can handle a little more.


edited for more info
also check out this article http://www.iaei.org/subscriber/magazine/00_b/pauley.htm
 
Status
Not open for further replies.
Top