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Need help with wiring my new MIG

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  • Need help with wiring my new MIG

    Hello all,

    Long time reader, first time poster.

    I have a dilemma (I'm a beginner). I just bought a just about brand new Miller Challenger 172 250 Volt 50 amp MIG for use in my 68 Mustang project.

    The welder comes with the plug that looks like this:

    This is a NEMA 6-50P. My garage is wired with just a regular 120V household outlet.

    The problem I have is that I live on Army housing (Stationed at Fort Lewis, WA) and the housing authority told me I could not get the garage rewired for 250V or at least they won't have anything to do with it.

    An alternative that my father in law said was to just use an extension cord to the dryer outlet. It's about 10 feet away from the garage but the plug for the dryer is this:

    This is a NEMA 10-30R outlet.

    I looked at the breaker box and the breaker for the dryer has two 30AMP breakers attached together to make it one unit.

    Would it be advisable to just make an extension cord with a NEMA 6-50P at one end for the welder and a NEMA 10-30R to plug into the dryer outlet?

    Do the two 30AMP breakers that act as one switch mean it's actually 60AMPS?

    If I did do the extension cord, how big of wire should I use?

    Any help would be greatly appreciated by anybody. I have no experience with anything relating to electricity as I am just an Infantryman in the Army and the most I do with electricity is replace batteries in my weapon sights.


  • #2
    No the double pole 30 amp breaker is only good for 30 amps NOT 60... So as I see it you have two options replace the 30 with a 50 amp breaker and make your extension cord or even better if you can put in a new breaker and outlet if their is room in the breaker box... Or better yet get a 110 volt welder, if this machine is for body work a 110 volt will do just fine. Hope this helps


    • #3

      Do not replace the two 30A breakers with a double pole 50. If you have a dryer problem, you don't have the protection you need (ie..wires melting and starting a fire.)

      If there is room in the panel, install a 2/50 breaker and run a new circuit to the garage using 6/2 wg romex.

      If you don't feel comfortable with this, find a friend that has electrical experience and get some help. This would be your best bet. Most of all, take the safest approach.


      • #4
        Amps to Wire Size

        Just to clarify for safety's sake:

        The 30A existing circuit should have 10g wire.

        A 50A circuit needs 6g wire.

        If you add a 50A breaker then you need to use 6g wire for a run under 25 feet and a new 50A receptacle. Make sure the ground is wired correctly. If it is a really long run you may want to jump up to a 4g wire.

        Remember this:

        14g wire use on 15A circuit
        12g wire use on a 20A circuit
        10g wire use on a 30A
        8g = 40A
        6g = 50A
        4g = 60A

        Good Luck,


        Thunderbolt AC/DC
        MM 175
        Maxstar 150 STL
        Blue Star 185 DX
        Spectrum 375


        • #5
          I may be missing something, but I have a Challenger 172 that is about 8-9 years old. It does not have to have a 50 amp outlet. The dryer outlet would be sufficient amperage, just need to make an extension cord adapter.
          Miller Challenger 172
          Hobart AC/DC Stickmate
          Older Sears AC Stick machine


          • #6
            I was just following up and saw the previous post so I decided to check out the model 172 specs. Seems it draws less than 20A. You need to verify the actual specs for your unit and we can advise from there.

            Check the plate with the model #, it should list the Amps @ 230V.

            Is the unit used?


            Thunderbolt AC/DC
            MM 175
            Maxstar 150 STL
            Blue Star 185 DX
            Spectrum 375


            • #7
              Darren..... I hate to tell you this but is it really worth a Court Marshal.... even if you do it better than the base maint. dept. could / would do if you ever have a fire it will be labeled your fault..... talk the wife into moving off post and get a house with 220 in the garage and after getting your land lords permission in writing them modify the wiring / pay someone to do it..... I'm not saying it is that hard once you get all the relevant info. but a hack job will get you in trouble quick....and FWI you will be fine running that machine with a 12 ga ext cord to about 70 if you can make up a cord with a male end to plug into the drier plug and a female end matched to your welder you will be in business until you can get the wife to move
              George W. Bush was saving your butt whether you liked it or not!
              Fear is temporary, regret is forever
              HH210 with SG


              • #8
                Here is the owners manual for that machine....just in case you don't have it
                George W. Bush was saving your butt whether you liked it or not!
                Fear is temporary, regret is forever
                HH210 with SG


                • #9

                  I'm a retired Colonel in the Army Corps of Engineers and have spent a little time in government housing so I know what you're up against.

                  First, check your owner's manual and verify the input amps required for your machine. I tried to download the manual for a Challenger 172 but couldn't find it listed (under resources-main page). I suspect you'll find that the unit draws considerably less than 30A @ 240V.

                  Assuming that's the case, I'd pick up a 25' or 50' 10ga extension cord from Lowes/HD and cut the ends off (cheaper than buying bulk cable). Install a 10-30P (dryer plug) on one end and a 6-50R (welder receptacle) on the other. That way you're good to go. You don't have to do anything with the circuit breakers in the electrical box. You won't have any problems with the facility engineer as long as you don't tamper with the electrical box (ie changing 30A breakers to 50A).

                  As I said, I'm not intimately familiar with your mig, but I run a Hobart HH187 hard off a 30A breaker. A Miller MM210 (a 210A mig) only draws 27A @230V.

                  When fabricating the extension cord, use the black and white wires for your hot leads. Use the green for ground.

                  Time to get to sparking
                  Last edited by SundownIII; 02-18-2008, 08:54 PM.
                  Syncrowave 250 DX Tigrunner
                  Dynasty 200 DX
                  Miller XMT 304 w/714D Feeder & Optima Control
                  Miller MM 251 w/Q300 & 30A SG
                  Hobart HH187
                  Dialarc 250 AC/DC
                  Hypertherm PM 600 & 1250
                  Wilton 7"x12" bandsaw
                  PC Dry Cut Saw, Dewalt Chop Saw
                  Milwaukee 8" Metal Cut Saw, Milwaukee Portaband.
                  Thermco and Smith (2) Gas Mixers
                  More grinders than hands


                  • #10

                    Hey Darrenfpc,
                    I have a 251 millermatic it draws 42 amps max You only draw that wild open if Look on the back of your mach not the plug type see what it really draws.Ok saying all that "I" ran my welder on a 30 amp plug for 2 month till I got a 50 amp plug with no problem But as "I" said before Thats me,You will have to decide for yourself.My plug was 24" from my pannel.All my wires are oversized
                    because I hate cutting it close always like it better than it needs to be.

                    Good Luck Darren...... Vernon