That's the easy answer out....
One thing I ran into a month ago is we ran #10 2-wire Underground wire- the type they use for outdoor LV applications, inside to some Trac 12. This was all fine and dandy as far as we could tell, and was really nice to pull because its got a really nice strand count; but like mdshunk was saying the temp ratings killed us.The hitch was that the transformer I was to run the wires into specified the need for 90 degree conductors inside the box. this wire was only rated for 60 degree. Due to the fact that it was LV it was a pretty easy fix. Whew..