60a breaker instead of 50a?

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I have some extra 6/3 Romex, so I decided to run an extra 240v plug for my welders.  The only breaker I have left is a 60a, which means I would have to buy another 50a.  Is there any reason I shouldn't use the 60a breaker, or will I be fine using it in place of the 50a?
Reply:Breakers are cheap...Maybe you can return the 60 and pick up a 50 for no cost at all. 6 guage wire can be used with a 60 amp breaker under certain conditions. Chosing the right breaker depends on how long the circuit is and what the temperature standards are. The "safety" of using undersized wire depends on several factors, is it going to be buried in insulation, is it going to be near flamable materials, is the wall where it will be run close to or attached to living space? I run my Syncrowave 300 (which actually has a rated output of 400 amps) on a 50 amp circuit and have only tripped it a couple time when I was running wide open.Ian TannerKawasaki KX450 and many other fine tools
Reply:The plug will be around 4-6' from the box, basically under the panel.  I actually found a 30a breaker, which I could use until I do pick up a 50a.  I just didn't know if I could use the 60a, but breakers are fairly cheap!
Reply:A 60A on #4 will be fine for a dedicated run up to 50ft. so long as it's not aluminum wire. For aluminum, go up one wire size.And then, after so much work...... you have it in your hand, and you look over to your side...... and the runner has run off. Leaving you holding the prize, wondering when the runner will return.
Reply:Step one - RTFM!  Many (some/most?) welder manuals list the electrical service requirements, including wire size, length (apparently not an issue in this case   ), and circuit breaker/fusing requirements.Note that although -some- welders may allow a 'mismatch' between the usual Code required breaker-vs-wire sizing because of duty-cycle exemptions, in those cases the ciruit must be DEDICATED to the welder and LABELED as such with something like "For Welder Use ONLY !! ".  The best laid schemes ... Gang oft agley ...
Reply:If it was my garage, I'd just use the one ya got. For such a short run there shouldn't be a problem. But I'm not an electrician and I don't think giving advice that might cause a fire is a smart thing to to do in a public forum. Cheers. Ian TannerKawasaki KX450 and many other fine tools
Reply:6 gauge copper is rated 55A in the 60 deg. celsius column of NEC Table 310-16, and 65A in the 75C column.  Non-metallic cable (NM, or "Romex") is required to be sized per the 60C column, so it's good to 55A.  However, if your load requirements don't exceed the ampacity of your wiring (for a fixed, known load), you're allowed to round up the breaker size to the next 'standard' size, which per the NEC is 60A (55A is not a standard size).  The cable is not overloaded assuming your welder does not put more than a 55A load on it*, so the breaker serves mainly as protection for short-circuits and ground-faults (shorts to ground), and also to protect against shorter duration higher amperage overloads.Perhaps you should post the nameplate current and lowest duty-cycle for the machine.  I suspect you have plenty of conductor for what you need, and there won't be a problem with the 60A breaker.  I'm using 10 gauge copper NM on a 50A breaker now for a 53A at 20% buzz box (legally), and could actually go up to a 60A breaker if I wanted to.*None of that includes the Article 630 provisions for duty-cycle based downsizing of conductors for arc welding machines, and also the provision for overcurrent protection up to 200% of the rated primary current of the welding machine (from the nameplate).  Art. 630 usually results in 'undersized' wiring and 'oversized' breakers or fuses.
Reply:The three welders I have are a Clarke 180a MIG, a Lincoln Power Mig 255, and a Lincoln Invertec v-275s stick/tig machine.  I think the max draw for the Invertec and Power Mig are all under 50a, but Ill have to check the plates.