[bran3b]

I just bought a welder, and discovered that the electrician installed the wrong 220v outlet. He installed the 3 wire with one verticle and 2 slanted prongs (sorry, don't know the proper name). I need a 3 wire that looks like a big 110v plug. I have bought the proper plug, but I am not sure which wire goes where. I have the ground in the middle (round) as directed on the back of the new outlet, but there is no mark for the white or black wires, which one goes on which side?