Thanks Rambozo,
This is what I've got: white wire from welder to narrow blade on 5-60, black to wide, green ground. At the whip, when plugged into 110 outlet, 5-60 receptacle on the end has narrow hole to ground at 0 volts, wide to ground is 120, 120 across narrow and wide. When I plug the welder into the whip, no change from before.
I took the 5-60 off and installed a 5-15- white to silver, black to gold, green ground. Corresponding outlet has 0 volts on wide blade, 120 narrow. That's correct, yeah?
Still no change. I never had it plugged in for more than seconds. I don't think it would fry instantaneously. With the 220 plug back on, it strikes easy and welds great.