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Discussion Starter · #1 · (Edited)
Hi I have a 220v 30 amp circuit that was hooked up to a three prong dryer plug. There is a red wire, black wire, and white wire that look to be about 8-10 gauge and then there is a bare wire that I assume is a ground, that is only about 14 gauge. I want to hook up a NEMA 6-50 plug for my welder. I have searched around the web and forum and I have read the white wire would be neutral and not used, only to use the two hots (black and red) and the ground. That doesn't seem correct to use a tiny ground wire on this plug. The bare wire was originally coiled around one of the screws holding the plug to the box. The other three wires were all connected to the plug. Can someone point me in the right direction?

Also, this is probably a separate thread but the wire is stranded aluminum, if it appears to be in good condition is it OK to use?

Thanks, here are links to photos, this is the only way I could figure out how to add them.
http://img135.imageshack.us/img135/8945/dscn3313n.jpg
http://img88.imageshack.us/img88/7955/dscn3312.jpg
 

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You can not use that wire on a 50 amp circuit.
You need to replace the wire with a #6/2 romex for the welder.
 

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You can do it. It probably won't meet code and if it burns, your homeowners ins probably won't cover it...
But in theory, all you would need to do is install a 30A double pole breaker at the panel & run the 2 hots to it and switch the white neutral over to the ground lug in the panel.
The 2 hots obviously go to the hots on the plug and the white (previously neutral) to the ground.
 

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Discussion Starter · #5 ·
Thanks for the replies. I'm just going to redo the whole thing or have it redone. Not a real pressing need for a quick fix i guess. I don't really see why it would burn but then again I'm not an electrician either.
 

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Why don't you just replace the plug on the welder? That would be easier.
 

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Discussion Starter · #7 ·
Why don't you just replace the plug on the welder? That would be easier.
That was the original plan, however I couldn't find one readily. I think it ended up being good because when I took the wall plug out it was in really bad shape, the terminals were falling apart. If I had found one and replaced the welder plug it seems like it would be incorrect. I would have a neutral where I should have a ground. If going that route I could just hook up the new plug I have in the same fashion as the old dryer plug but from what I can gather that is wrong.?
 

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That was the original plan, however I couldn't find one readily. I think it ended up being good because when I took the wall plug out it was in really bad shape, the terminals were falling apart. If I had found one and replaced the welder plug it seems like it would be incorrect. I would have a neutral where I should have a ground. If going that route I could just hook up the new plug I have in the same fashion as the old dryer plug but from what I can gather that is wrong.?
I don't understand what you're talking about. You had a 30A receptacle, and a welder that requires less than 30A, but has a 50A plug. You would just replace the plug with one that matches the receptacle. That's a standard dryer plug, so it's available at any hardware store or home improvement center (usually as a cord with a molded plug attached). Why would you "have a neutral where you should have a ground"? I don't know what that refers to.

It's good to replace a damaged receptacle, but I would have replaced it with a 30A to match the circuit and put a new cord on the welder.
 

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I don't understand what you're talking about. You had a 30A receptacle, and a welder that requires less than 30A, but has a 50A plug. You would just replace the plug with one that matches the receptacle. That's a standard dryer plug, so it's available at any hardware store or home improvement center (usually as a cord with a molded plug attached). Why would you "have a neutral where you should have a ground"? I don't know what that refers to.

It's good to replace a damaged receptacle, but I would have replaced it with a 30A to match the circuit and put a new cord on the welder.
3 wire dryer receptacle is hot hot neutral(NEMA10-30), welder is set up for hot hot ground(NEMA6-50).
 

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3 wire dryer receptacle is hot hot neutral(NEMA10-30), welder is set up for hot hot ground(NEMA6-50).
Ah, yes. Now I get it. Not a problem. The neutral/bonding conductor in a 3-wire 120/240 connection will work perfectly well as a grounding conductor for a 240V-only connection.
 

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Discussion Starter · #11 · (Edited)
Sorry I posted this before I saw the most recent replies. Ignore.

I don't understand what you're talking about. You had a 30A receptacle, and a welder that requires less than 30A, but has a 50A plug. You would just replace the plug with one that matches the receptacle. That's a standard dryer plug, so it's available at any hardware store or home improvement center (usually as a cord with a molded plug attached). Why would you "have a neutral where you should have a ground"? I don't know what that refers to.

It's good to replace a damaged receptacle, but I would have replaced it with a 30A to match the circuit and put a new cord on the welder.
That's probably because I'm doing a bad job explaining it because I don't really know what I'm talking about. Let me really beat this to death.

I did go to home depot and my favorite ACE hardware store that always has everything I need and neither place had the plug.

When you say replace the plug with a thirty amp to match the circuit I get it, makes perfect sense. So i would hook up the plug just as it was.

Then I find a plug for the welder that fits the wall outlet i just installed. The welder cord has two hots and a green ground. then I hook up the plug. But the green ground is now plugged into the white neutral in the wall, right? That's what I meant by a neutral in place of a ground. Someone above said to change the neutral over to ground at the box, then its seems to me it would be how it should be.
 

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Someone above said to change the neutral over to ground at the box, then its seems to me it would be how it should be.
It would be. It would be functional. IMO, when protected with a 30A Breaker, it would also be safe for use (assuming your connections are sound). Code takes into consideration other factors, such as - if you left tomorrow, and an electrician went to chance the plug back, you'll have changed things to ways not intended.

You could indicate that you've changed the neutral to ground by marking with green electrical tape. Still may not meet code, but at lease it would indicate that it's been changed...
 

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Did the welder come with a 50A plug on it? If so you'll need to plug it in to a 50A receptacle. I wouldn't change the 50A plug to a 30A plug. It's obviously designed that way.
 

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Did the welder come with a 50A plug on it? If so you'll need to plug it in to a 50A receptacle. I wouldn't change the 50A plug to a 30A plug. It's obviously designed that way.
He says the rated current is 19.8A. A 30A plug/circuit is more than sufficient in that case. Just because the manufacturer chose a 50A plug doesn't mean a 30A plug would be inadequate.
 

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Discussion Starter · #16 ·
Did the welder come with a 50A plug on it? If so you'll need to plug it in to a 50A receptacle. I wouldn't change the 50A plug to a 30A plug. It's obviously designed that way.
Actually it wasn't designed that way. It came with a cord, one end hard wired into the guts of the machine and blank on the other to chose your own plug for the outlet you have. At the time I had a 50 amp circuit with the 6-50 plug.
 

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Discussion Starter · #17 · (Edited)
Ah, yes. Now I get it. Not a problem. The neutral/bonding conductor in a 3-wire 120/240 connection will work perfectly well as a grounding conductor for a 240V-only connection.
mpoulton, No offense, your positive right? I am reading different things about using the neutral for ground, I don't have enough knowledge to deduce anything from what seem to be various conflicting opinions on the WWW. Thank you for the replies.
 

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mpoulton, No offense, your positive right? I am reading different things about using the neutral for ground, I don't have enough knowledge to deduce anything from what seem to be various conflicting opinions on the WWW. Thank you for the replies.
It's definitely acceptable in this situation. The circumstance where it's questionable (no longer allowed for new installations, but was standard for decades) is when the load uses the neutral connection as both a current-carrying conductor and also a chassis bonding conductor. That's potentially dangerous. However, your welder has no 120V loads internally so it does not require a neutral, only a bonding conductor.

You probably have a NEMA 10-30 receptacle (two slanted prongs and one L-shaped), which was originally intended as a 3-pole 3-wire ungrounded configuration. If you really want to feel better about using this in a 2-pole grounded configuration, you could replace the receptacle with a NEMA 6-30, which looks like a 15A 240V except bigger. It's functionally identical (there would be no electrical difference at all), but is intended for this application.
 
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