Wiring of old welder
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  1. #1

    Wiring of old welder

    I inherited my father in-laws welder a very old Westinghouse 250 amp arc welder. It will replace my Ward’s welder for better duty cycle, much longer leads, etc.

    However I’m perplexed by the wiring of this old welder. Just before I cut off the old plug to replace it with one that will fit my outlet, I noticed it only had two prongs with the neutral missing, figured it had recently been broken off. To wire the new plug did as I’ve done many time before…. Two 110 legs and a neutral.

    Plugged in the welder and nothing. Re-checked the plug and all connections were correct and well seated. Pulled the cover off the welder and discovered the switch is connected by two wires; while the neutral is no where to be found, cut short right were the wires enter the unit. That explains why there was no neutral prong on the plug.

    I know this welder works, somehow in this configuration; it’s the one I learned to weld with before my father in-laws passing a few years ago. With my understanding of 220 circuits I don’t know how to hook up this old welder. The only thing I can think of is my outlet needs wired with two 110’s on one leg… is this possible?

    Great site by the way plan doing a lot of reading here.

    Scott

  2. #2
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    Re: Wiring of old welder

    First: neutral is not required for machine operation. Machine itseld requires grounding though for safety reasons. So, if this is an older machine there is a chance that it supposed to be grounded by direct wire from machine to ground bar - not neutral - ground (copper) - make sure that you understand the difference.

    Second: the term "Two 110V" - sounds peculiar. Modern residential power supply called "One phase 3 wires". Which means there are 3 wires coming to your house - two hots and one grounded neutral. Colors: red, black, white. Beteween any hot and neutral - 120V. Between two hots - 240V.

    So, if this is 240V machine - you have to bring two hots to the plug. It sounds like you might be using the same 120V on each prong.

    It could be that you have old 3ph wiring - then this is a different story - please, verify.

    Third: "Pulled the cover off the welder and discovered the switch is connected by two wires; while the neutral is no where to be found, cut short right were the wires enter the unit." - please, rephrase - hard to understand.

    Fourth: can you post some pictures?

  3. #3

    Re: Wiring of old welder

    Were talking the same thing just different wording. Didn’t mean to get all caught up in the schematics of the outlet. Guess I failed in trying to relay the outlet is wired correctly (as you described).

    See if I can clarify what is happening with the machine where the problem lies. Basically it only has two wires. The way I’ve always understood how 240 (220) works, it needs at least three wires; two hot's and a neutral.

    Hopefully this picutre thing works. The pic is of the power switch from inside the welder. The black and white wires, on the right, are the only wires connected to the power supply (outlet/plug).
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  4. #4
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    Re: Wiring of old welder

    Quote Originally Posted by Scott R View Post
    Were talking the same thing just different wording. Didn’t mean to get all caught up in the schematics of the outlet. Guess I failed in trying to relay the outlet is wired correctly (as you described).

    See if I can clarify what is happening with the machine where the problem lies. Basically it only has two wires. The way I’ve always understood how 240 (220) works, it needs at least three wires; two hot's and a neutral.

    Hopefully this picutre thing works. The pic is of the power switch from inside the welder. The black and white wires, on the right, are the only wires connected to the power supply (outlet/plug).
    Wiring looks just fine. Although BLACK and WHITE would imply 120V...
    1. Are you positive that this is 240V machine?
    2. There is a tag plate next to wires coming from switch - can you provide a picture of it? I tried to zoom but it is not readable.
    3. Can you measure 240V AC? I mean if you have proper voltmeter and you know how to use it...
    4. Can you make a shot of back panel? May be there is some tumbler?
    Last edited by Nomand; 08-05-2008 at 02:38 PM.

  5. #5
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    Re: Wiring of old welder

    Almost forgot - 1ph 3 wire sytem DOES NOT require 3rd wire for 240V. Two hots - that's all.

  6. #6
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    Re: Wiring of old welder

    Only thing, sometimes on the older 220 volt buzz boxes the cooling fan is only 120 volt and runs between one of the hots and neutral.

  7. #7
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    Re: Wiring of old welder

    Scott,

    US/Canada wiring for 220/240 v uses two wires. The two hot wires, which by convention are black/black or black/red.

    If you have a third wire, the white neutral wire, then you can still get 220/240V between the two hots -and- you can get 110/120V between either hot wire and the neutral wire.

    In addition, there is the ground wire. Which by convention is the green insulated or bare copper wire.

    Older equipment that uses 220/240V for the major purpose (welder, electric stove or dryer, etc) might also use some parts or things inside at 110/120V (a cooling fan, a timer motor, a light bulb, etc). That older equipment would uses the two hots to get 220/240V (just like always) and would also use the ground wire (which is connected back at the breaker panel to the neutral) to get the desired 110/120V. So, it would use three wires in the plug and outlet, the two hots and the ground.

    The 'modern' way of wiring would use four wires, the two hots and the neutral wire and the ground wire. So 'modern' electric stoves or dryers have the four-prong plugs and outlets instead of the 'older' style three-prong ones.

    So, 240V equipment would use either three wires (hot, hot, and ground) or four wires (hot, hot, neutral, and ground). But not hot-hot-neutral.

    A better pic of that wiring diagram decal might help us help you.

    Also, verify that the machine -is- a 220/240V machine (usually a nameplate/sticker on the back of the machine near the power cord will give specifics on voltage/amperage/etc) and that the outlet/circuit you are using is a 220/240V one.
    The best laid schemes ... Gang oft agley ...

  8. #8
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    Re: Wiring of old welder

    "Westinghouse 250 amp arc welder"

    I highly doubt it is a 120v machine
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  9. #9
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    Re: Wiring of old welder

    Ed Conley
    http://www.screamingbroccoli.net/
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  10. #10

    Re: Wiring of old welder

    It works!

    It had been working the whole time. What threw me off is first no fan (not used to that) second it is ultra quite, could only hear a slight hum with cover off and when I put an ear right down near the unit.

    Thank you for setting me straight that 240 does not need a neutral/ground to work. Learn something new everyday. I still don't undersand but....

    By the way The diagram shows how to configure the machine for 220 or 440. For 440v you remove those plates, just to the left, and place one plate between the two center post.

    Guess this is just the first of many stupid questions, but i promise to fully utilize the search function before I post.

    Thanks to all for helping get my head out of my arse.

  11. #11
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    Re: Wiring of old welder

    120v 240v wiring
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    Ed Conley
    http://www.screamingbroccoli.net/
    MM252
    MM211
    Passport Plus & Spool gun
    TA 185
    Lincoln SP135 Plus- (Gone to a good home)
    Miller 125c Plasma 120v
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    SO 2020 bender
    Beer in the fridge

  12. #12

    Re: Wiring of old welder

    I’m so glad I found this site where I can ask questions of people that never make mistakes, especially simple ones.

    Thank you for that very warm welcome.

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    Re: Wiring of old welder

    Quote Originally Posted by Scott R View Post
    I’m so glad I found this site where I can ask questions of people that never make mistakes, especially simple ones.

    Thank you for that very warm welcome.
    Do not take it too personally. Aparently, this is men's site, so sometimes gets physical... You're lucky that you avoided Zapster saga...

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    Re: Wiring of old welder

    See if I can clarify what is happening with the machine where the problem lies. Basically it only has two wires. The way I’ve always understood how 240 (220) works, it needs at least three wires; two hot's and a neutral.
    Only needs two to work, needs three to be safe. If that ground never was there or has been cut off, you should get one or re-provision it.

    If it is there, ignore this.

  15. #15
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    Re: Wiring of old welder

    Quote Originally Posted by Broccoli1 View Post
    "Westinghouse 250 amp arc welder"

    I highly doubt it is a 120v machine
    Good catch Broccoli1. doh!!

    Scott R,
    Let me say welcome and you had five of the best helping you sort this one out and I'm glad you didn't get 'tingled'.
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  16. #16
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    Re: Wiring of old welder

    Two wires (the two hots) gets you (and the machine) 240V. Which is what it needs to weld.

    If there really is no fan, OK.

    But -if- there is a fan, it may/might need that ground wire to get 120V to the fan (if it is a 120V fan).

    Anf the ground wire is kind of important for safety too. (drastic understatement there, folks!) Most of the time, the ground wire will somehow get connected to the metal chassis/frame of the machine (look for a screw or stud or terminal ring or tapped hole,maybe with a stub of green/bare wire on it). Also see if the inside of the chassis (or the manual if you are so lucky to have or find one) has a schematic. Check the schematic for the presence of a ground wire. It could be labeled as such, or in symbols it is the 'three dashes in diminishing size that sort of looks like an upsidedown pine tree'.

    The grounded chassis is usually important for safety, because if a 'hot' wire gets loose or frayed or otherwise can let electricity go where it isn't supposed to, and that hot wire touches the frame/chassis, then the chassis is now 'hot'. With no ground, it stays hot. If you touch the frame/chassis and give the electricity a place to go (one hand or other body part touches the machine and another body part touches a grounded 'something' or even worse somehow gets connected to the other hot wire circuit), you get shocked or zapped or electrocuted. If the frame/chassis is grounded, as soon as the errant 'hot' wire connects to the frame/chassis, there will be usually be a spark and most likely the breaker will trip.

    btw, neat pic of the 'old transformer on wheels' on the hobart site link. But for some reason, the bright metallic blue paint doesn't seem original.
    The best laid schemes ... Gang oft agley ...

  17. #17
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    Lightbulb Re: Wiring of old welder

    You should not run the fan back to ground if it is a 120v fan you need to power, but rather go from one hot to the neutral. Though not correct to go to ground 99% of the time it will be find even if you went to ground as long as bonding strap in main pannel is ok, but if you have any electrical troubles in the building (floating ground) wiring running fan to ground could energize the the frame of the welder or other equipment.

    As mentioned above (I had not fully read it before I posted so am saying the same thing), For safety you should also considder adding a ground line to the frame of the welder. Reason if a wire inside got hot and lost some insulation, cracked, came undone or what ever and touched the frame, without a ground the frame of the welder is live and could kill. If it is grounded you get sparks and a tripped breaker at the worst.
    Last edited by Timberwolf; 08-06-2008 at 09:11 AM.

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