Thanks for all replies.
So to try to answer your questions SlimSavage, it is not something I plan on using daily, it's basically for my farm equipment in case of a break down that needs to be welded and I would be happy to never use it at all. As far as the money part goes -- so if I was building a house and rafters were 2x8 which was OK but 2x 10's would be better, I'll pay for the the 2x10's knowing it would cost more but I would not have to worry in case of a heavy snow load, and 2x12 would be an over kill.
So I would rather go bigger than minimum, but not an over kill, suck up the cost, once and not have to worry it.
40 amp breaker, with an #8 or #6 or what other type of wire size or breaker?
Again, thanks for any help.