How is a 14 wire sufficient? The specs are...230V, 25 A, 60 HZ , single phase and 120V, 20A, 60 HZ, single phase!
How long of a run are you putting in? Personally I'd put in a 40 or 50 amp with 8AWG, that way you would have some growth room if say you bought an older tig welder. It wouldn't be much more up front.