By Gfretwell:
"I really don't start thinking about derating unless I see a very pretty bundle with carefully aligned cable bundles. The cables in the middle are cooking. If you fan them out between holes they can breathe."
I wish I could claim to be the guy who came to this realization but I'm only repeating something that I heard from smarter people.
If you're talking about a residence. And you have only 12 and 14 AWG NM (no ranges heaters and such). Think about the load you're likely to find throughout the entire building at any one time. Even if you bundle all those circuits, I don't think in the vast majority of cases you'll have enough current to cause enough heating that you would need to derate.
Edit: fixed spelling
[This message has been edited by Physis (edited 12-29-2004).]
