Plug wiring not right

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  #1  
Old 08-02-06, 09:16 PM
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Plug wiring not right

Hey All,

I need a little advice before I complete wiring for my welder. Here are some details:

I bought a welder from a relative, a Lincoln ARC welder, and took the plug out of her garage to install it in mine. I took the plug apart and noticed what I think is a problem. At the breaker box, the wiring appeared all correct. #6 Black and red to a 50 amp breaker, copper ground and white neutral to respective bars in the box. The #6 wire is 24 ft. long from the box to the welder plug. The plug is a 3 prong 125/250v plug.

Upon taking the plug apart to take it off her wall I notice that the black, red and white all appear correctly wired into the plug, but the copper ground has simply been cut off, not attached to any ground in the plug and is just there under the black plastic. It appeared to have been cut so that it couldn't be seen hiding under the wire covering.

This seems very wrong to me and I need to know if the copper ground is supposed to be connected to part of the plug. It was connected in the breaker box but then just stopped when all the other wires were run into the plug. Is the ground therefore not even doing anything?

I actually used the welder in this woman's garage several times and it worked fine. I asked her about the wiring and she claims her husband (who passed away) did it and I thought for sure that the husband once told me an electrician did it after completing the wiring from the house to the garage. I can't remember who did the welder for sure.

I need a bit of help on this one. Should I expose more of the copper ground and connect it to the plug like the other wires and if so, where do I connect it?

Thanks much.
 
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  #2  
Old 08-02-06, 09:45 PM
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Its not right but it isnt the worst on a scale of 1 to 10. The arc welder is strictly 240 volt so the white wire (neutral) isnt needed just two hots and a ground. It appears that the installer chose to use the white wire for ground he should have used the bare wire. Doesnt really matter as for a functioning ground wire though. However, when you install your welder use #6-2 with ground cable or 2 thhn #6's for hots and a #10 insulated green for ground if you use conduit.
If you do have a white neutral ran to the receptacle just cap it off at both ends. Use bare or green for your ground wire.

Roger
 
  #3  
Old 08-02-06, 09:54 PM
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Thanks Roger.......let me make sure I understand.

Currently the plug is wired with #6/3 and the white neutral is not actually necessary. The bare copper (which appears to be #10) should have been connected but was not and the white has been used in its place.

So, why do you think the bare copper was hooked up on the breaker box, or whoever wired the setup used too much wire to begin with?

According to your advice what I will do is put everything back together as follows: #6 black and red wired to 50 amp breaker. Bare copper wired to ground in box and ground in plug. White neutral capped off in box and at plug to not be used at all.

Everything else is good to go with the plug and breaker? Do my relay back to you sound correct?

Thanks again......I really appreciate the input. I've wanted to get this thing put back together but I've waited due to the hesitation on the ground wire issue. I wasn't quite sure what was going on there.
 
  #4  
Old 08-03-06, 04:15 AM
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I suspect that whoever wired this felt more comfortable using a larger wire for the ground rather than a smaller one. Either that or they preferred to hook up the insulated wire in the plug rather than the bare wire (to lesses the chance of a short).

Under normal operation this does not matter, at least electrically. However, in the event of a fault this would present a problem if the panel with the breaker is a sub panel and not the main panel. The problem is that fault current would go to the neutral bus, and not to the ground bus. However, even this is not a big deal.

Bottom line. Make the new connection properly.
 
  #5  
Old 08-03-06, 06:24 AM
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Currently the plug is wired with #6/3 and the white neutral is not actually necessary. The bare copper (which appears to be #10) should have been connected but was not and the white has been used in its place.
Yes

So, why do you think the bare copper was hooked up on the breaker box, or whoever wired the setup used too much wire to begin with?
From my experience there seems to be confusion by many DIYers when a neutral is needed. Some seem to think it is a ground wire (its not)...it's a current carrying wire. It is needed when the equipment or appliance being served needs 120 volts. A typical installation needing a 6/3 with grd (H-H-N-Grd) is a range/stove that requires 120 volts and 240 volts. But a 240 volt appliance only needs two hots and ground. So my guess is the person who did the original hook-up was confused and did not understand the difference of purpose between the two wires or the requirements of the welder. He chose incorrectly for whatever reason. Wasnt the worst mistake but not right just the same.

The bare wire in your example is the equipment ground which facilitates a low impedance path back to the transformer center tap (neutral) so that fault current will be great enough in amps to trip the breaker if a short occurs. Otherwise it does not carry current but is for safety reasons. Without it a short to the metal case of an appliance would simply energize the metal at line voltage creating a shock or worse hazard to your family.
It is normal at the main panel for grounds and neutrals to be on the same bar...this is where they bond to the grounded conductor (service neutral) and is a wanted situation. Different story if it is a sub-panel as Bob mentioned.

According to your advice what I will do is put everything back together as follows: #6 black and red wired to 50 amp breaker. Bare copper wired to ground in box and ground in plug. White neutral capped off in box and at plug to not be used at all.
Yes...

Everything else is good to go with the plug and brreaker? Does my relay back to you sound correct?
Yep

Thanks again......I really appreciate the input. I've wanted to get this thing put back together but I've waited due to the hesitation on the ground wire issue. I wasn't quite sure what was going on there
I wish everybody would be this concerned before doing something dangerous..... unknowingly. Electricity isnt user friendly when misunderstood....

Good luck

Roger
 
  #6  
Old 08-03-06, 09:33 AM
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Much appreciated. I am going to get it wired up today and try the welder. I'll let you know how everything turns out.

If I live to tell about it that is
 
  #7  
Old 08-03-06, 03:20 PM
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Roger and racraft..........well I got everything wired up and installed. I capped off the white neutral and used the bare copper ground in its place as is meant to be. I put a 50 amp breaker in the box, used #6 wire, black and red to 50 amp and bare copper to ground bar.......turned everything back on and nothing bad happened.

Power worked and welder turned on as expected. I didn't try welding anything yet, but I'll get to that. Does it sound like everything is good to go? If the breakers didn't kick, the welder turned on and I wasn't zapped, it seems to me that things are good.

By the way, I checked the welder which looks to be an old model (Lincoln).....it is has a max power rating of 225 amps and a standard setting of 75 amps. Am I ok with the wire and breaker setup I am using? I have 100 amp service to my garage being fed from the main panel in my house.

Thanks again.
 
  #8  
Old 08-03-06, 08:10 PM
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Yeah it sounds like your in good shape. Now that you have told us about the welder I'm confident your set up is good to go. 50 amp breaker and #6 cu is the typical way we wire the lincoln arc (stick type) welders.
One concern... is this a sub-panel in a attached garage or detached? There may be some things you need to check based on how you answer. Nothing serious just need to be sure if you need a ground rod and/or need to seperate the neutral and ground bars in the sub.
FYI... the output rating you mentioned doesnt actually help us in knowing what breaker and wire size. The input amps at rated output is the info that is needed. The old Lincolns didnt give this info on their nameplates only in the installation instructions. At any rate this appears to be one of the older stick welders that required a 50 amp circuit. If not post back with what you have. You can actually have smaller conductors than #6 cu on that welder because it has a 20% duty cycle but in a home shop we always run the 6 awg.

These were excellent welders and still had the copper windings. I am still using a 225 amp AC/DC model that is over 25 years young.

Roger
 

Last edited by Roger; 08-03-06 at 08:24 PM.
  #9  
Old 08-03-06, 08:52 PM
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Roger......my sub-panel in the garage is a Cutler-Hammer with the separate neutral and ground bars. I have a 3 wire feeder from the house (in the form of #2 aluminum wire to handle 100 amp service) and a bare copper ground from the garage sub-panel to a ground rod. I consulted two electricians and a Cutler-Hammer rep before completing the job and here's how I did it: 100 amp breaker in house main panel, 3 wire feed (underground) from house to garage: H-N-G connected to the sub-panel accordingly due to the 100 amp breaker, neutral bar and ground bar. Then #8 bare copper from ground bar to ground rod.

Sound ok? I hope so.........everything works fine, no problems at all, no excessive heat in the wires, no breaker trips, etc.

Here's the welder info.
Input: Single Phase, 230 volts, 60 cycle, 50 amps and it is a Lincoln model AC-225-5. I can't find anything on it regarding the manufacture date and the serial no. is only partially legible b/c of the plate being worn down. It's all black and has a 2 minutes out of 10 rating except for at 75 amps.

It's solid, it has always worked well in the past and I'm looking forward to many years of service even though it's GOT to be pushing 25 years old likes yours.

What do you think?
 
  #10  
Old 08-03-06, 10:37 PM
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Sounds like you are fine with your set-up. In your case with a three wire feeder (H-H-N) to a detached building/garage subpanel you cannot have any other metallic paths (copper water line, etc.) connecting the house with the garage if it is detached. Otherwise you should have a 4 wire feeder.
What you have with the cutler panel is bonded neutral and ground i.g. the bars are connected electrically... which is what you want with a 3 wire feeder. If you had a 4 wire feeder (H-H-N-Grd) then you would unbond those bars to make them not electrically connected. This is usually done by removing the green bonding screw or a metal stap between the two bars... it just depends on the panel design.
Take a look when you get time and see if the two bars in your sub-panel are bonded...they should be. Sometimes that bond is utilizing the metal of the panel chassis to accomplish this connection.


Roger
 
  #11  
Old 08-04-06, 08:43 AM
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Ok, thanks.

I'll check the box on the bonding issue, but without looking at it right now I am sure they told me to unbond the bars in the box and I distinctly remember taking the strap out of the box on that recommendation. I am not using one bar for connecting both neutral AND ground wires......each wire has its own bar in the box. I have all ground connections on the left of the box/breakers and all neutral connections on the right

I'll double check for sure and reply.
 
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