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I need to do some exhaust pipe welding and this house has a 4 wire 220v outlet and the older welder has a 3 prong 220v plug. I understand 3-phase and 110v enough to avoid a funeral , but this confuses me.
I bought a 4 prong plug and I don't want to guess how the 3 wires to the welder hook to that 4 prong plug.
Here's pics of the panel, the outlet, the new plug, the 3 welder wires, and the welder wiring schematic. I'm hoping one of you fine gentlemen is a qualified electrician and can tell me which color wire goes to which prong on the plug.
The 40 Amp breaker in the panel pic (off position) goes to the outlet.
Last edited by HOXXOH; Feb 9, 2017 at 09:45 PM.
Reason: clarification
I believe you have a regular single phase 220 volt set up. two hots a neutral and a ground. The three wire set up should be 2 hots and a neutral, if its a single phase 220. And I'd bet it is. The ground is optional on some set ups. That's why the ground is usually smaller. The neutral is the same size as the two hot wires. The neutral serves as both a neutral and ground in the three wire set up. Some newer wiring panels have separated neutral and ground bus bars. Depends on the electrical inspector.
Just looked at the panel again. Your neutral and ground bus bars are not separated. They are all tied together. You definitely have a single phase 220 on that 40 amp breaker. The welder schematic shows L1, L2, and ground. L1 and L2 are the two hots, the ground is the neutral and ground.
I believe you have a regular single phase 220 volt set up. two hots a neutral and a ground. The three wire set up should be 2 hots and a neutral, if its a single phase 220. And I'd bet it is. The ground is optional on some set ups. That's why the ground is usually smaller. The neutral is the same size as the two hot wires. The neutral serves as both a neutral and ground in the three wire set up. Some newer wiring panels have separated neutral and ground bus bars. Depends on the electrical inspector.
Just looked at the panel again. Your neutral and ground bus bars are not separated. They are all tied together. You definitely have a single phase 220 on that 40 amp breaker. The welder schematic shows L1, L2, and ground. L1 and L2 are the two hots, the ground is the neutral and ground.
While I certainly appreciate the help being offered, I didn't see anything that was a definite answer to my bottom line question. My background is mechanical engineering, so electricity is not my strong suit.
I needed a simple answer to which color wire from the welder (green - white - black - and there is no red) in the #3 photo should connect to which terminal on the plug in the last photo. I'm very confident that the green is the ground and will connect to the bottom "U" shaped terminal, but terms like "hot" and "neutral" aren't telling me a color. Since all the terminals on the plug fell out when I took it apart, brass and silver screws may not be in their original locations.
To those who responded before this post, I re-took the photos of the receptacle and plug for clarification and to orient them in the same direction. The red wire coming from the panel is going to the left center position of the receptacle (viewed from the plug side as 9 o'clock), the solid black to the 3 o'clock and the black/white at 12 o'clock. Of course, the 3 and 9 o'clock locations are reversed when looking at the plug photo.
The welder is using the white as the other "hot" leg. The volts should read 220v between white and black. The ground should read 110v to the white and 110v to black. As stated before in your electrical box the ground (green) is connected to the neutral buss.
The check is the 220v between L1 & L2. In this case connect L1 to black L2 to white.
On the breaker side you will have a white hooked alongside the black going to the terminals on the breaker. I know it looks like your are hooking a white to a direct short to ground. As long as your read 110v between white and ground (green) there is no short.
Last edited by PA_BLUE_C6; Feb 9, 2017 at 10:53 PM.
I needed a simple answer to which color wire from the welder (green - white - black - and there is no red .
Black and white from the welder go to the 3 & 9 o'clock position on plug (doesn't really matter which one goes where in this case). Green from welder goes to the ground lug as you figured.
Black and white from the welder go to the 3 & 9 o'clock position on plug (doesn't really matter which one goes where in this case). Green from welder goes to the ground lug as you figured.
Thank you. Exactly what I needed.
I'll get to welding tomorrow.
Still, thanks to the others, even though I failed to comprehend.
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welding exhaust - need electrician help
, but this confuses me.
Exactly what I needed. 
