Over sizing the breaker question?

[ASE_MasterTech]

There is a section in the NEC dedicated to welders. They fall into a category all their own. I believe its section 630. I can't believe the number of calls I get from electricians with all sorts of bad information. I always point them to the NEC, rather than give them advice. It concerns me that a large number of the electricians never heard of it. But suffice it to say, there are very specific guidelines that should be followed, though they are more forgiving because they fall under a duty cycle limited category. Normal rules don't apply....

I beg to differ, but 'normal rules' do apply.
The simple fact is that wire gauges are determined by voltage/amperage load in ALL applications, AC or DC, this is due to 'heat/conductivity' considerations.
I built the home I am in & put additions (add-a-level) on 2 previous homes, & on rough & final electrical inspections I have never been told to provide an 'appliance' for circuit approval.
If the breaker/fuse is 50amp then the wire from the f/b to the outlet should be at least 6awg.
What you do after the outlet (ie-extension cords, etc..) really depends on heat dissipation (#8 wire may be ok for 50amp extension because it's not in a wall or conduit), distance is also a factor to consider.