Derating

[hershey]

As a residential electrician I rarely have the need to derate conductors in conduit. That being said I'm really weak in figuring how to calculate it. Is there any place on Mike's site or someplace else that might explain this better than the NEC

 

[infinity]

Here's a good article that Mike wrote for EC&M:

http://ecmweb.com/nec/electric_conductor_size_matters/

 

[hershey]

Thanks Rob, With that article and about 2 hours on line I think I've got it figured out. Unfortunately, I've got to redue what I did today.