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Thread: Dual 220 plug for welder/plasma cutter combo

  1. #1
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    Dual 220 plug for welder/plasma cutter combo

    My 50a welder outlet is 20' from my welder so I run a #8 extension cord to it. I'm thinking about getting a plasma cutter and wonder if there's a way to create a dual plug on the end of the cord so the plasma and welder can be plugged in at once. They'll run separately, never at the same time. Sure I can unplug one and plug in the other but was just curious about the possibility.

    And BTW, are most 220v plasma cutter plugs Nema 6-50P like a welder?

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    Re: Dual 220 plug for welder/plasma cutter combo

    Yes same as the welder style. I don't see why you could

  3. #3
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    Re: Dual 220 plug for welder/plasma cutter combo

    Couldn't gang 2 4x4 boxes and wire up 2 receptacles. Kind of like 110 volt duplex outlets, using 1 cord.

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    Re: Dual 220 plug for welder/plasma cutter combo

    Better to just put in a 2nd receptacle next to the first. Depending on how your first was done you may be able to pull a second set of wires to have another circuit.

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    Re: Dual 220 plug for welder/plasma cutter combo

    Quote Originally Posted by JD1 View Post
    My 50a welder outlet is 20' from my welder so I run a #8 extension cord to it. I'm thinking about getting a plasma cutter and wonder if there's a way to create a dual plug on the end of the cord so the plasma and welder can be plugged in at once. They'll run separately, never at the same time. Sure I can unplug one and plug in the other but was just curious about the possibility.

    And BTW, are most 220v plasma cutter plugs Nema 6-50P like a welder?
    You could. A couple 4" square boxes (the deeper ones), two 6-50R receptacles, some 1/2" or so knock-out fittings, a couple raised front covers for 2". You could even weld them together if you space them just the right amount so the front covers aren't binding against each other. Can you tell I'm making something similar right now?
    1st on WeldingWeb to have a scrolling sig!



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    Re: Dual 220 plug for welder/plasma cutter combo

    Quote Originally Posted by Oscar View Post
    You could. A couple 4" square boxes (the deeper ones), two 6-50R receptacles, some 1/2" or so knock-out fittings, a couple raised front covers for 2". You could even weld them together if you space them just the right amount so the front covers aren't binding against each other. Can you tell I'm making something similar right now?
    You would still want a nipple connecting the 2 boxes to prevent wire chafing. You certainly could weld something to keep the boxes from twisting. I think you would need 3/4" or 1" nipples to fit the required wire thru

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    Re: Dual 220 plug for welder/plasma cutter combo

    Maybe use two close nipples or chase nipples side to side so the boxes stay in line and tight.

    You would be smart to use two 4 11/16" boxes instead of 4 square 1900 boxes and put the outlets in industrial covers and screw them to the boxes easily.

    Box,
    https://www.homedepot.com/p/RACO-4-1...-260/205758429

    Cover,
    https://www.homedepot.com/p/RACO-4-1...-878/202056914
    Last edited by danielplace; 07-03-2021 at 10:03 PM.

  8. #8
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    Re: Dual 220 plug for welder/plasma cutter combo

    Quote Originally Posted by M J D View Post
    You would still want a nipple connecting the 2 boxes to prevent wire chafing. You certainly could weld something to keep the boxes from twisting. I think you would need 3/4" or 1" nipples to fit the required wire thru
    Yup, you're right. 3/4" or 1" would work a lot better with more space. Once you put the raised covers on, and put them side-by-side, with just a smidge clearance between the raised covers (they are slightly larger than the 4" sq boxes), it only leaves about 0.150" (roughly 5/32") gap between the two 4" sq boxes; eazy peazy to bridge that narrow gap . A couple of quick tacks on the corners to hold the clearance, then scrape off the galvanization off the the outside (even though the inside will still have it, better than nothing), then a couple short beads on the top/bottom/back and it's solid!





    I should probably rotate the boxes since two of the sides only have the 3/4" knock-outs, and the other two sides (the tops in the pic) have the 1" knock-outs (which would be facing each other if they are used).
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    Re: Dual 220 plug for welder/plasma cutter combo

    Quote Originally Posted by JD1 View Post
    My 50a welder outlet is 20' from my welder so I run a #8 extension cord to it. I'm thinking about getting a plasma cutter and wonder if there's a way to create a dual plug on the end of the cord so the plasma and welder can be plugged in at once. They'll run separately, never at the same time. Sure I can unplug one and plug in the other but was just curious about the possibility.

    And BTW, are most 220v plasma cutter plugs Nema 6-50P like a welder?

    Sorry, I don't know the part numbers but generally you can get a rugged, plastic, water resistant surface mount box in which a suitable power point can mounted. Two of those can be mounted either back-to-back or one after the other on the end of the extension cord.

    Jack

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    Re: Dual 220 plug for welder/plasma cutter combo

    I built a 4 recepticle tree for my 3 welders and plasma cutter. All on the same breaker and cable.

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    Re: Dual 220 plug for welder/plasma cutter combo

    I have two welders on this cart so I wired a box on the back of the bottom one so the one on top can plug into it. This way only one input cord is needed for the two welders.





    My welder extension cord with two boxes...




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    Re: Dual 220 plug for welder/plasma cutter combo

    Great! It can be done then. If I wind up getting the plasma, I'll do it. I'll probably make it so it plugs in to the existing 6-50R on my extension cord rather than remodeling the cord in case at some point I want to use my cord as it is now.

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    Re: Dual 220 plug for welder/plasma cutter combo

    The problem is making the splices in the number #6's.

    You are almost forced to double tap one of them. That is illegal but on a extension cord probably ok and consider it a do what ya gotta do kind of thing.

    If you have some old SJ cord or can sacrifice what your working on for a little length get some wire from the cord to make your jumpers with. It is fine strand and more flexible copper/covering that say a piece of THHN.

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    Re: Dual 220 plug for welder/plasma cutter combo

    You dont really need to make a 3 way from the heavy conductors, wire nut 2 number 10 to the 8.

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    Re: Dual 220 plug for welder/plasma cutter combo

    Quote Originally Posted by Sberry View Post
    You dont really need to make a 3 way from the heavy conductors, wire nut 2 number 10 to the 8.
    No way to say if you can safely reduce the #8's to #10's without knowing what the welder and the plasma cutter actually draws and their duty cycle.

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    Re: Dual 220 plug for welder/plasma cutter combo

    You really can ss long as they are not a 252 class feeder with hi duty and rven then would be a mosyly moot ossue in all but a production fab shop. I dont pwn a vord heavier than a 10. Basically any time there are multiple recepts the combination mist trip thr breaker on thermal before it overloads the wire they are spliced to.
    With really new machines could safely splice 2 to a 10 but its not really legal to wire it that way.
    This is to others,, not really danial in particular,,, but with 2 recepts,, neither machine by itself would over heat wire or trip breaker, 2 small macjines could run at once, wont hurt wire or trip and 2 larger machines at same time would trip a bresker before overheating the wire.

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    Re: Dual 220 plug for welder/plasma cutter combo

    What you cant do is increase the breaker to run multiples, the factory wired machines sre designed for 50. Certain portion of the equipment relies on the circuit breaker for fault protection the same ss power strips on 120 general use circuits, same ss any ewuipment designed to be connected to a current limited circuit. It doesnt always require that much but depends on breaker for internal fault protection. Electric range wired on this principle. AC buzzer same way to some extent at least for fault and thermal slightly different.

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    Re: Dual 220 plug for welder/plasma cutter combo

    Really the only time a breaker protects building wire for thermal is a general use circuit w multiple recepts. In most,, almost all others the breaker is simply an off on switch which allows enough current to pass to do the work and limits the short circuit. Not truley thermal protection in the eay its often thought of and commonly portrayed.
    Thermal is done by applied load and often wire sized up for faults rather than adding additional overcurrent protection.

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    Re: Dual 220 plug for welder/plasma cutter combo

    The thermal on a power strip isnt really a breaker,,, its a thermal overload and short circuit duty is still provided by breaker. Cords not thermal protected but fault protected, same as internals of range or the welder especially old buzzers.

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    Re: Dual 220 plug for welder/plasma cutter combo

    I realize we are talking about a extension cord that will be out in the open where it is easily seen and can really only be loaded while operator is present so maybe some of what I think your trying to say may not pose as much a risk.

    For wiring that is part of the permanent electric system then you should never be reducing wire sizes midstream to something less than it is fed with for sure.
    You can normally only do that is like say the larger wire has only been run for voltage drop not to deliver full ampacity like say a 200 foot run of #8 on a 30 amp circuit then reducing to #10 at close to the end before it reaches what it is feeding. Notice no wiring in the run can be less current carrying ampacity than the ampacity of the breaker protecting it except when you start to factor in some of the special rules they have for welder outlets.

    Those special calculations for welding outlets were written to save cost on large installations of numerous larger welding machines at a distance from the panels where they are trying to save cost on the wire.

    Personally I believe a 50 amp outlet is best served with the full 50 amps means it needs #6's.

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    Re: Dual 220 plug for welder/plasma cutter combo

    You dont reduce midstream. Yes they are for welders, that is kind of the point. If there was some gain there would be more incentivr to up the wire but there really isnt and other equipment does not come 6 50. If this was another device we would say there was a co spiracy to sell more wire,, ha but,,,, despite some popular belif the code is really well thought out in this regard and for this allowance. If it was a problem they would have changed it in the last 90 yrs.

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    Re: Dual 220 plug for welder/plasma cutter combo

    The owners manuals do account for distance and voltsge drop. The min wire for a buzzer is 12 at near 80 ft. This is allowed on a 50 breaker. No one thinks that is a great idea in real life and i dont do it for 50A and dont use 14 on 30 even though it is legal in some cases.
    A fussy guy can tell a little difference in wire size with 120V and 14 vs 12 north of 50 ft with machine wide open. Its minor and only fussy testers could tell.
    The difference in 12 vs 10 on a buzzer is a pinch. Especially on longer circuits. Losses for all practical purpose disappear with a number 10 and diminish with larger wire.

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    Re: Dual 220 plug for welder/plasma cutter combo

    For wiring that is part of the permanent electric system then you should never be reducing wire sizes midstream to something less than it is fed with for sure.
    Reason I bring this up is these fundamentals of circuit design are so often misunderstood and poorly quoted on the welding forums. Its kind of simplistic to just say 6 must be used on every 50 circuit which isnt true and most of the worlds equipment not cord and plug is wired differently. Most of the time its not dangerous to do this but can be.
    People seem to think cause they did it its ok,,, I wired my wrelder this way so its ok when they may not have done it correctly and strayed from the instruction and introduced code violations they have not considered when the learning has been rather hand to mouth.
    I have been over this on other forums,,, a lot of it is what I didnt know and assumed back at some point, I kind of aware and know where the diy has it wrong so yto speak and am aware of the missing links. Also cones a lot of nonsense from guys that really should know better.
    The concept of overheating a wire is obsessed on,,, it clouds other issues and often seems to give people a feeling they know something about something they dont. On another venue there was similar discussion of the merits of using number 4 and 8o breaker so they could share the outlet with all the machines. This is due to the flawed assumption that all the breaker does is thermal for the wire and totally skips its more important function when part of a welder circuit which is short circuit interruption. Now we have a welder with a 12 cord,,,, and internals that depend on the breaker for fault hooked to an 80A breaker and the owner has a warm fuzzy feeling cause the 80 wont over heat the 4 he has daisy chained to 50 outlets. Introduces several violations, one big one that the ground wire in the cord is now on 80 and rated for 50 and allows 5-0 machines to be plugged to 80,,,, but,,,, we got guys claim to be knowledgeable and defend this with a screaming match which proves they really dont know what the f they talking about.
    There are other requirements for recepts with the exception of welders. But this fundamental principle is why we dont simply enlarge the wire and use all 30A for 120V or do not allow 30 on 20 recepts. Its not due to the fact we might overheat the wire,,, that would be simple to solve with bigger wire but due to the fact all the equipment that depends on the breaker for fault,,,,, the equipment plugged in to it is not rated for it. When this comes up in conversation and the logic is,,,, I think,,, its really different than knowing and understanding.
    I was at a place the other day owner wired and I look and horry shat, floating panel and ungrounded circuits and guy says,,,, I think and I was told and I really had to stop him right there and say,,,, what I am going to explain about this isnt my
    opinion, its not what I think about it and I didnt invent it. We work at it a little and he come around but its really rather important as this guy does remodel and hooks up additional circuits all the time and important he has some understanding what grounded electric circuit means.

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    Re: Dual 220 plug for welder/plasma cutter combo

    True electricians seem to often grasp this with some kind of instinct. I have to be shown,,, I am an installer or wireman more than an electrician and am confused bu more than 3 or 4 wires and sometimes with those. But what I speak to is what the manual calls "qualified" installer in the sense that we are familiar with the code in this aspect and some nema to be able to decipher the language in the instruction manual which can be confusing at best,,,, such as mac breaker of 30 for the new welders which isnt a complete explanation of what it means.
    Now,,, this is an opinion,, or I think,,, but a more clear explanation for the small welders so popular now needs a better explain in the manuals due to the diy installs.
    Last edited by Sberry; 3 Weeks Ago at 09:56 AM.

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    Re: Dual 220 plug for welder/plasma cutter combo

    Quote Originally Posted by JD1 View Post
    My 50a welder outlet is 20' from my welder so I run a #8 extension cord to it. I'm thinking about getting a plasma cutter and wonder if there's a way to create a dual plug on the end of the cord so the plasma and welder can be plugged in at once. They'll run separately, never at the same time. Sure I can unplug one and plug in the other but was just curious about the possibility.

    And BTW, are most 220v plasma cutter plugs Nema 6-50P like a welder?
    The thing really makes this ok in some theoretical way is that the breaker will overheat before the number 8 wire if you could apply load long enough and enough. The 8 will run any single machine comes with 50A and any 2 smaller machines without overheating and in reality a 10 would be sufficient 1 at a time. But the benefit of trunk and branch is it runs 1 thing better than a smaller dedicated line, 2 things sufficient for 2 with it being equivalent to smaller home run etc.
    Most of the machines hooked to 50A welder circuits are 12 cord.

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