Wire size?????????
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  1. #1
    Join Date
    Mar 2009
    Location
    Denver, Colorado
    Posts
    2

    Wire size?????????

    Sorry if this is a question that has been asked many times before but I’m new to this.

    I picked up a Century 84231 (230AC/140DC) for cheap and I am in the process of running a 50 amp 240 volt outlet (NEMA 6-50) for it because the power cable coming out of the welder has a 50 amp 240 volt plug on it. A 50 amp outlet requires a 50 amp breaker and 6/2 wire, right? I noticed that the cord coming out of the welder is marker 10/3 but it has a molded on 50 amp 240 volt plug, what is up with that? Every table I have checked say 6 gauge wire for 50 amps but then this cord coming out of the welder has 10 gauge wire with a 50 amp plug on it, why?

  2. #2
    Join Date
    Jun 2008
    Location
    Central California
    Posts
    3,769

    Re: Wire size?????????

    I'm not an electrician and don't know all the codes and perhaps not all the reasons, but I'd say:
    The wire in a building is generally both long and enclosed. There is no way to tell what will be hooked into the circuit, so if it is a 50 amp, 220v circuit, the assumption is that it might have to supply that power for quite some time. The wire size is designed to allow this to happen without any overheating. When codes are written, various things such as the type of wire insulation and maybe even the fact that resistance goes up with increasing temperature together with the area's ambient temperatures, are considered.

    The cable into the welder is fairly short, is exposed, and is dedicated to that machine which is assumed to be operated according to it's duty cycle which is well below the 100% that is used for the house wiring. It also needs to be somewhat flexible so that probably figures into the equation. Plus, some companies are 'cheaper' and don't always use what might be optimal for the job.

  3. #3
    Join Date
    Jan 2004
    Location
    Las Vegas, NV
    Posts
    3,175

    Re: Wire size?????????

    Not only that, but the house wiring is actually designed around a 125% duty rating for good measure!

    Now, that said, there is usually a very small chance of something other than a welder to be plugged into a NEMA 6-50R receptacle in most places. If you permanently label the receptacle "For Welder Use Only" you can also use the smaller wire on the permanent wiring to the receptacle. This is according to the NEC (National Electric Code) Article 630.

    I would run 10/2 NM cable to the receptacle if that were my machine.

  4. #4
    Join Date
    Mar 2009
    Location
    Denver, Colorado
    Posts
    2

    Re: Wire size?????????

    Thanks for the info, this makes sense now. I think I will go ahead and run 6-2 wire, that way if in the future I need to plug in a 50 amp item other than a welder I will have the capability to do so. I can not see this ever happening but you never know.

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