Originally Posted by gsweave
When you can find a welder mfg that recommends an extension cord as an upgrade to their equipment, let me know
They all suggest against em.
Right now, the extension is masking/confusing his real problem.
Eliminate it from the problem.
Continue to troubleshoot other causes.
All welders use some sort of power cord, extension or not. If the cord is sized properly and terminated correctly there is no difference between an extension cord and hard wiring. You have no idea, based on the info provided by the original poster, that the cord is masking or confusing anything. The cord appears to be helping but you choose to ignore that. I took the time to go look at the Panasonic machine the guy has and it appears to be inverter based but I could be wrong because they never call it that. The guy could test his current wiring by simply borrowing another welder and seeing how his circuit handles it. If it's fine with another welder then there is likely an intermittant fault within his machine.