I just bought a Miller Thunderbolt Xl 225 AC/150DC welder and I'm a total newbie. I just registered on the forum tonight so I could ask these questions. I did some stick welding when I was a kid, but it's been about 20 years or so. Hopefully it's just like riding a bike . Well I'm planning to run a 50 amp circuit for the welder and my welding will have to be done outdoors, on the side of the house opposite our electric panel. That means I'll need about 75 feet of extension cord, or so, to get me comfortably outside. I looked into buying some #6-2 Romex that I could use to make an extension cord, and it'll cost just about 130 dollars or so for the length I need. I'm not too happy about using the Romex for an extension cord because it's so stiff and not really the stuff to use for an extension cord. It's really meant for permanent wiring. With the welder's 20% duty cycle, can I use a thinner gage wire than #6? Would a 75 foot long generator cable with 10 gage conductors and rated for 30 amps be adequate? Is there anything else anyone would recommend for an extension cord of this length? Thank you very much for any help you can provide.