4 conductor to 3 conductor

Discussion in 'Electrical Forum discussion & Blog' started by Mojoe, Jan 10, 2014.

  1. Mojoe

    Mojoe New Member

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    I have a Honda ES6500 generator with a 4 conductor 125/250V 30 amp outlet. I want to power my Miller 211 welder that has a 3 conductor plug. Do I just ignore the neutral since I'm going with 220 instead of 120? I couldn't find an adapter so I bought some parts and will make my own. Any thoughts?
  2. jwelectric

    jwelectric Electrical Contractor/Instructor

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    No neutral is required for the welder but you may have a problem with inrush currents caused by the welder on that tiny generator.
    When you strike an arc with the welder the generator governors will open up causing a voltage surge as well as the cycles will elevate which the welder might not like.
  3. DonL

    DonL Banned

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    I think you will need the Neutral for the Miller 211.

    The Wire feeder controller and motor runs on 120V.

    Just connect the 4th ground wire to the welder ground and that will ground the piece that you are welding.

    You should use the safety ground.


    Have Fun.
  4. hj

    hj Moderator & Master Plumber Staff Member

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    The third wire is a neutral and ground so connect it the generator's neutral pole. The welder may have a dedicated ground lug elsewhere.
  5. Mojoe

    Mojoe New Member

    Messages:
    14
    Location:
    NH
    Thanks for the input, definitely some things I hadn't considered. I can turn off the automatic idle control to eliminate the surge factor. Input amps @ rated output for the welder @ 230V is 24.3. The 230 receptacle on the generator says 27 amps - probably too close figuring in a surge factor but I'm only welding at less than half output. I'm welding 11 gauge [1/8"-] and the welder is rated up to 3/8". I thought it would just be easier to use the generator since I'm not at home but now I'm a little confused. - Should I connect the welder plug's ground terminal to the generator outlet's neutral terminal? There is no external ground on the welder except for the ground cable that gets attached to the work piece. DonL, are you saying I should combine the generator outlet's neutral and ground on the welder plug's ground terminal? The generator isn't huge but I think it was the biggest Honda available at the time I bought it. The thing cost almost $5K and runs the essentials when the power goes out. It's liquid cooled, good on gas, reliable, and relatively quiet - def. not an el-cheapo.
    Last edited: Jan 11, 2014
  6. DonL

    DonL Banned

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    I was saying to connect Ground on the Gen to Ground on the welder. Just for safety.

    The neutral needs to be on a Current carrying conductor, not the ground wire. That welder uses 120 for the wire feed even tho it runs the Output transformer on 240V for the welding wire.

    That Welder will work with your Generator, as long as the Wire feeder speed is consistent.


    If the Generator bogs down, then you will not make a good weld. It needs to stay at 60 HZ, or close to it.



    Have Fun.
  7. Mojoe

    Mojoe New Member

    Messages:
    14
    Location:
    NH
    DonL, What you say makes sense except that if I were going to hardwire it at 240V, it would just be two hots and a ground so I would assume that the same rule would hold true for the generator but how is the neutral terminal different from the ground terminal on the generator? It's the source. The grounds and neutrals come together at the source don't they? The feed motor is variable speed so maybe it is DC like the weld output? What about the fan? Some kind of secondary system or transformer?
  8. hj

    hj Moderator & Master Plumber Staff Member

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    IF you were hard wiring it, you would connect the wires to the two hots AND THE NEUTRAL, not the ground. Three wire cords connect the ground and neutral together. IF you rewire it for 4 wires, you disconnect the internal ground from the third (neutral) lug and then connect it to the fourth wire (ground).
  9. Mojoe

    Mojoe New Member

    Messages:
    14
    Location:
    NH
    I guess I wasn't specific enough about which lead I was referring to because I think it's right but I'm obviously no expert. I also have a 230V Lincoln stick welder that also has a 3 wire plug. It's always been hard wired to a 30 amp dryer type outlet fed by 2 hots and a ground. Some 230V submersible well pumps are also just 2 hots and a ground while others are 3 wire. What I'm trying to do is to adapt the 4 conductor generator outlet to the 3 conductor welder plug rather than adapt the welder to the generator. The reason is because the welder has interchangeable plugs for either 120V or 230V that thread on to the cord to make it easy to change from one to the other. Thin metal is easier with 120V. I got a 4 conductor plug for the generator's 230V output and a 3 conductor outlet to match the welder's 230V plug and a piece of 10/3 w/ground to connect them. I don't mean to sound disrespectful but I don't understand why the welder's 3rd conductor should be to the generator's neutral instead of the ground if it could be hard wired to ground - unless the wire feeder and fan were 120V but I think they are DC because if they weren't, it couldn't be hard wired to ground. Do the generator's neutral and ground leads connect? I just don't want to damage any expensive toys unnecessarily and appreciate the value of group input. I also appreciate the frustration involved in dealing with this [me]. Thanks again for your help.
    Last edited: Jan 11, 2014
  10. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    I'd rather have a safety ground if the thing does not need a neutral. A neutral can carry current, the safety ground only does if there's a fault.

    Without knowing how the thing is wiring internally, it may be kind of hard to say. If it always internally tied ground and neutral together, I'd just hook up the hots and ground. Do you have a model number or an internal wiring diagram of the welder?
  11. Reach4

    Reach4 Active Member

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    I expect the protective ground terminal is wired to the generator frame, and I expect a connection of the neutral to the frame. I would like to think there is a fairly easy way to separate these to connect the generator into a panel through a transfer switch or a lockout. Some are very much against lockouts and have some reasonable arguments. As far as I can tell, the lockouts are still permitted at least some places. That the neutral is connected to the frame should be easy enough to confirm with a low range ohm meter between neutral and protective ground (or frame) while the generator is off and not connected to anything.
  12. Mojoe

    Mojoe New Member

    Messages:
    14
    Location:
    NH
    The welder is a Miller 211 but I don't have any internal diagrams. I was thinking the same thing about testing for continuity between the neutral and ground terminals with an ohm meter. Even if there is continuity, why use the neutral instead of the ground?
  13. Reach4

    Reach4 Active Member

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    2,127
    Location:
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    For your purpose, none. Neutral is used if there is some 120 v load.
  14. DonL

    DonL Banned

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    The Neutral and ground are most likely tied together at the generator.

    Looking at the manual the Fan runs on AC and the Control runs off of a separate step-down transformer and it is unclear if that transformer is running on 120 or 240V.

    A VOM should tell you how it is wired, and if 120V is required for the control board.

    I would pop the top on the welder and have a look see, Instead of guessing.

    Leave the top off to see where the smoke comes from.


    Good Luck.
  15. jwelectric

    jwelectric Electrical Contractor/Instructor

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    2,532
    Location:
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    The welder came with a cord and end cap which will tell you that if it is a three wire no neutral is needed. If it came with a four wire then the neutral is needed. This is an easy problem to solve and there is no need to start taking anything apart or using a meter, just look at the cord and end cap that came with the welder.

    It doesn’t matter what duty cycle the welder is being used with the load will be the full amps that the welder is capable of drawing.
  16. hj

    hj Moderator & Master Plumber Staff Member

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    quote; 30 amp dryer type outlet fed by 2 hots and a GROUND.

    You may be intentionally misreading the previous posts. IT IS NOT A GROUND. It is a NEUTRAL, that is also attached to the body of the appliance to function as a ground. When converted to 4 wire operation, the "green" internal ground is disconnected and connected to the dedicated ground.
  17. DonL

    DonL Banned

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    The best way to tell what you have is the Pigtail.

    If it is 3 wire and all conductors are the same size then the appliance most likely uses the 120 Volt side. Like a dryer Drum Motor runs on 120V. Even tho the heating element runs on 240V.

    The Neutral is the ground. And the older outlets mark it as Ground, but it is Neutral. It is Neutral and Ground at the breaker panel or generator, if bonded properly.


    A simple connection can become complicated. Special precautions need to be taken, when welding.


    Be careful playing with electricity.
    Last edited: Jan 12, 2014
  18. Mojoe

    Mojoe New Member

    Messages:
    14
    Location:
    NH
    I'm not sure what you mean by "intentionally misreading", maybe it's just terminology like my use of the word "plug" for cord cap. If I wire something with 2 hot wires and a wire that goes to the chassis, ground bus, or a rod driven in the ground, I call it a ground. I'm not trying to change the welder into a 4 conductor connection. I'm trying to change the generator into a 3 conductor. The welder's manual shows a 230V connection with L1, L2, and Earth Ground. To me, that means ground but maybe some call it neutral. The 230V plug that comes with the welder is a NEMA type 6-50P and all 3 conductors are a different size. They refer to the welder as a 211 MVP which means "Multi Voltage Plug" since it can run on either 115 or 230V just by switching the plug on the end of the cord. Both the 230V and 115V plugs have 3 conductors on the business end where they plug in but have 4 conductors on the end that joins to the welder's cord. It would probably be interesting to know just how and why they designed it like this and the details of how they power the other motors and controls but I've got a lot of things going on right now - an excavator with it's $1K muffler blown apart. I'm no master electrician but I've wired houses, machinery with mag switches - single and three phase, phase converters, automotive and equipment, etc. and haven't had any smoke shows yet. I've been bitten a few times but nothing serious. I did cut a live wire once after being told it was shut off. That was some real welding with no mask. I've hard wired this welder to a 2 pole 30 amp breaker and the ground bus on a sub panel and it worked fine so please understand my reluctance to wire it to the neutral terminal on the generator instead of the ground. The ground terminal on the generator's 230V outlet shows continuity to the chassis but the neutral terminal doesn't. I'm always up for learning something - hopefully not the hard way this time.
  19. Mojoe

    Mojoe New Member

    Messages:
    14
    Location:
    NH
    JW, Do you mean the welder will draw the same amount of power no matter what the setting is or how high I turn it up?
  20. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

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    Location:
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    The fact the third wire is smaller implies, to me at least, it is not a current carrying lead and is intended as a safety ground. I'd leave the neutral out of it.

    When running it on 120vac verses 240vac, it will either limit the power on 120vac, or draw twice as many amps under the same situation. The main reason to run things on higher voltages is you can use smaller wires and get the same power.

    If I had to guess, I'd guess there's a multi-tapped transformer in the welder to handle the dual-voltage.
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