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New cord for Miller 330 a/bp

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  • New cord for Miller 330 a/bp

    Picked up a nice clean Miller 330 a/bp, but need to put a new cord on it. The place I bought it from had a 10/4 cord on it, which doesn't seem big enough (might have been ok for them, since it was running 460 volt). I've got plenty of power in the shop, and am wanting to put it on a 100amp circuit. I'm fine with getting the wire from the breaker to the welder, but what about from the welder to the box? I have some 6/3 cord, but not sure if that would work or not. Also, what would people recommend for a junction box? Would I just be able to get a large enough box, and use split bolts like these to connect the wires?

    I'll be within about 25' of the panel, so if I'm correct, I wouldn't need a disconnect at the welder. Thanks!

  • #2
    Isn't that machine capable of some high draw on HF? I'm not sure who put 10/4 on it, but they should be hung at sundown (even at 460V). I'd start by looking at some amp/wire size charts like the following:

    I'm a big fan of disconnects -- have them on most of the equipment even when close to the panels (e.g. my "smaller" 10hp air compressor is 8' from the panel and still sits on a Square D disconnect even though it's only 40-50 amps FLA (can't remember)).

    I'd also get a licensed electrician to help --- well worth the money. I'm a retired EE (Boeing and Northrop Grumman) and still use licensed electricians -- those 2nd and 3rd set of eyeballs (a norm for Boeing and NG) are value added always.
    Last edited by Crepe Myrtle Farmer; 10-29-2017, 09:21 AM.
    ESAB TIG 252 with Miller CoolMate
    Spectrum 875
    Diversion 180
    Oxy-A (Harris, ESAB, Ox Weld)
    Miller 252
    MM 211
    CST 280
    Trailblazer - Kubota


    • #3
      10 ga wire ain't gonna cut it. To power that machine, well mine at least, at full power you need 96 amps on single phase. That machine is pretty skookum. Hard wired to a wall disconnect is a good idea. You can get them with a fuse or a breaker too. Not really sure what you plan to use those split bolts for. I've always called them "kearnies", but I know that's a brand. Either way, I'd consider using copper ones for that amount of current. Connecting electrical wires with dissimilar metals just seems like a bad idea to me.


      • #4
        You probably want #2, and could get away with #4 for most purposes, but since all you have is #6, I'd go ahead and buy the #2 copper conductors for 240V input.

        Without knowing more, I wouldn't slam the previous people too hard for the #10 at 460V. They could easily do 50A input on that, and get away with a bit more, and they may have only used its lower half.


        • #5
          EDIT: After some more searching, looks like I should be able to use some flexible conduit between the disconnect and the welder, so that would avoid having to use SOOW, and can use individual conductors. I would like to keep it as flexible as I can, in case I need to move it around some (have already built a pallet for it, so moving it is easy).
          Last edited by cj7jeep81; 10-29-2017, 10:31 AM.


          • #6
            There is nothing "easy" about moving an 860 lbs welding machine around.


            • #7
              Originally posted by ryanjones2150 View Post
              There is nothing "easy" about moving an 860 lbs welding machine around.
              With a pallet jack it sure is Close to the top of best things I've bought is a pallet jack, and building a gantry crane. Makes moving equipment so much easier.


              • #8
                I'll agree on the gantry for sure. My machine is one running gear I built for her and she was hanging from my gantry during the Harvey flood. But most people don't have a pallet jack or a gantry.