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I have good access to Aluminum B type SE wire connected to a 40 amp breaker. It is a dedicated circuit. There are only two capped wires and a thin app 2 mm silver color (aluminum?) wire that is unsheathed and wrapped around the other two capped wires. I will need to shut down power and uncap the wires to see if they are copper or aluminum. The wire is in a junction box in a very good place for me to run new wire off of it, to a good area in my garage where I want to be able to plug in a 130 amp combination flux core mig/stick mma welder that uses a standard extension cord type wall plug. Everything I have read states that with the welder at full 130 amp capacity running on a 6/10 cycle that the 40 amp breaker is plenty. I will check in the next few days if those wires are copper or aluminum. Does this sound safe, and is it doable?

Armand
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Robert
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  • There seems to be some inconsistency in what you are telling us, here. Please [edit] to clarify. You start with stating you have aluminum wiring, but you end with needing to check if the wiring is aluminum? Makes no sense to me. Is the "dedicated circuit" feeding some other thing, and you're trying to add a welder to it? That probably won't work when the other thing turns on. – Ecnerwal Aug 26 '23 at 00:50
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    Does the welder _DRAW_ 130A at 120V, or does it _produce_ 130A at 36V? The former definitely blows the breaker; the latter would be just within the 4800 watts the 40A breaker can provide. (Power in watts is voltage times current.) – keshlam Aug 26 '23 at 01:59
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    The latter, @keshlam, pretty clearly. Arc welders are normally known/called/identified by their (maximum) output amps. – Ecnerwal Aug 26 '23 at 02:36
  • Please clarify your specific problem or provide additional details to highlight exactly what you need. As it's currently written, it's hard to tell exactly what you're asking. – Community Aug 26 '23 at 02:48
  • What's the nameplate I1eff or I1max (aka *primary* current) of your welder? – ThreePhaseEel Aug 26 '23 at 05:00
  • Depending on the welder input requirements, that breaker might even be over sized. The welder should have instructions stating what it needs from a circuit. 40 amp circuits are usually 240 volts with two hots. A 240 v circuit with three wires can be two hots and ground(good) or two hots and neutral(bad). – crip659 Aug 26 '23 at 12:31
  • Thank you to all who responded. I came into this unprepared, because I first need to know what's under those wire caps. Copper or aluminum. I will remove those wire caps this weekend and i'm hoping I see copper. I will update after seeing the wires, and if I am able to I will post a pic. I am kind of curious though...for 17 years, all the electric work I have done in this house, I have seen only copper. Why would the electrician have installed aluminum for the electric range? Again, thank you all. – Robert Aug 26 '23 at 15:08
  • @Robert -- electric ranges are big enough current draws that aluminum starts to become viable at those wire sizes – ThreePhaseEel Aug 29 '23 at 02:33

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