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petite morty · Feb 22, 2008, 03:36 PM

I have a 240 V, single phase arc welder. It has a black, a white, and a green wire in the line cord. I want to wire a plug end onto it so I can plug it into my existing clothes dryer receptacle, which is a three prong unit (I live in the U.S. by the way). The receptacle has two slanted prongs, and a center prong that's L shaped. I want to know how to wire the plug on the welder line cord.
I had assumed that the ground wire (green) would go to the center, L shaped prong, and the black and white would go to the slanted prongs (and it would not matter which side they went on). But then I started looking on the web, and it looks like on a three prong receptacle, the center prong is called a neutral. For wiring a dryer, I think the ground would just be attached to the neutral wire at the dryer wiring block. So I am still guessing that the ground (green) would go to the center prong. But someone please let me know what to do here... :confused:

EPMiller · Feb 22, 2008, 04:54 PM

Originally Posted by petite morty

I have a 240 V, single phase arc welder. It has a black, a white, and a green wire in the line cord. I want to wire a plug end onto it so I can plug it into my existing clothes dryer receptacle, which is a three prong unit (I live in the U.S., by the way). The receptacle has two slanted prongs, and a center prong thats L shaped. I want to know how to wire the plug on the welder line cord.
I had assumed that the ground wire (green) would go to the center, L shaped prong, and the black and white would go to the slanted prongs (and it would not matter which side they went on). But then I started looking on the web, and it looks like on a three prong receptacle, the center prong is called a neutral. For wiring a dryer, I think the ground would just be attached to the neutral wire at the dryer wiring block. So I am still guessing that the ground (green) would go to the center prong. But someone please let me know what to do here....:confused:

What model of welder is it? Does it require more than 30 amps of current? If not, put the plug on the cord. You are correct on which wire goes to which prong. On a 3 wire dryer receptacle the neutral and ground are the same conductor back to the panel.

stanfortyman · Feb 22, 2008, 04:56 PM

What you want to do is technically not legal, but not at all dangerous.
The center prong IS a neutral for a dryer, and you will be using it as a ground. This is still safe because a neutral is designed to carry current, and your ground will not ever carry current. The ground is there as a safety backup.
There are instances where this might not be a wise thing to do, but for a dedicated 240v load you are fine.