I'm adding wiring for a 3hp 3ph lathe. I'm goint to use a VFD when 1 ph input. I'm out of slots in my breaker box. So I am going to add another box about 20' away from the main box. I'm going to feed it off the breaker that ran the mill. Off of this 2nd box I'm going to run the lathe and mill. Only one machine will be run at a time. However I may move the air compressor to the 2nd box at a future date. I have a 50a pushmatic breaker I can add to the original box. Since I don't have the NEC handbook, I need to know what gauge wire to run 20' that can handle 50amps. The wire choices @ Menards is for 8 or 6 gauge THHN. It looks line #8 is sufficient, but I just want to be sure.
Thanks, Wayne