Posted by David Sherman on Wednesday, June 20, 2007 at 21:01:38 :
In Reply to: Need help wiring a 220v plug on spot welder posted by DG on Wednesday, June 20, 2007 at 20:24:23 :
For 240V, white and black are meaningless. Both are hot. You can hook either one up to either flat blade. I agree you should make sure the green really goes to ground on the welder. Whenever I wire 240, I wrap black tape around the white wire just to make it clear to anybody looking at it in the future that it's hot. Ideally, they'd use a cord with green, red, and black for 240, and those are the colors you get if you have a 4-wire cord (with white for neutral) but it's a lot more common to use standard black/white/green cord for 240 with the understanding that the white in that case is the other hot phase.
It sounds like you definitely do have a 20 amp 240V plug, but the 20 amp 120V plug is very similar looking, it's just that the vertical and horizontal blades are swapped. I've been fooled by them a time or two.
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