Yeah I'm just guessing on the 20Amps cuz some fellas say they've popped 15A breakers running a 120v welder. So lets say it was 16Amps that's 5% voltage drop at the end of 100 ft of 12ga.
This forum has a huge 'history' of 120v welders NOT working,,, that has become become FACT, to the point that even members (who could not POSSIBLY know) will argue the point and even get MAD. All based on zero EVIDENCE, just speculation. They seem to WANT it to be true (for some reason).
So LNK,,,, (who does not appear to have been born yesterday, or even 2 weeks ago) posting that it can be done, with the further detriment of ~5% voltage drop, is a curiosity. :thumbsup: That's why I'd like to see the weld pic. But anyway I understand you didn't take a pic cuz you had a task to do, not necessarily entertain people on the internet.

But there ARE some here who want to learn.