Welding Tips and Tricks

Hello,
Last year I picked up a clean Miller Thunderbolt XL from a welding shop that was downsizing. The retailer they bought it from put a 75 ft electric cord on it with new Nema 6r50 plug. I also just bought a Hobart Handler 190. My question is, can I cut the 75 ft long cable off (at maybe the 10 ft mark) and add a female end to make a 65 ft long extension cord to use with both welders? I know it seems like a no brainer, but the cord says 'ROYAL 10/3 TYPE S00W on it. I know 10 gauge should be fine with the Hobart that only needs a 30 amp breaker, but I'm puzzled as to why they used that cord for the 50 amp Miller. I'd like to think that if a welding supply house put it on, it must be okay and won't overheat. Thoughts?

That 10/3 cord is pretty light for that current draw. I'm guessing that they didn't use the machine to it's full capacity and were therefore able to get away with it. 75 feet is a log way for an undersized cord.
As far as you cutting it down to make a multi-purpose cord, no problem. It would be nice if it was at least # 8 or #6 wire, but then again that would be expensive.

I assume your 10-3 is running as 10-2 w/ground, i.e. single phase 240V, due to the plug?

Yes, 10 ga. is light for a 75 foot length. Fine for 20A service, acceptible for 30A in duty-cycle service, but for 50A it's really questionable. If you set it up on a 30A circuit, you limit the danger, as the breaker will trip before you overload the cord.

If you're running three-phase, or 480V single phase, 10 ga.is fine, but that plug suggests otherwise.

Steve S

Yes, single phase 220. What gauge was the original cord on a Thunderbolt or Hobart Stickmate? If I just pull the whole thing I would want to replace it with the right type cord. I can always use this cord as a kickass extension cord for 110. Overkill though. All the pre-made extensions I see are 10/3 for 50 amps, but no longer than 50 ft. Maybe I'll just try a shorter version and see how it works out.

Yeah, without referencing the charts, 50' sounds about right for 10-3 50A (stranded wire... Solid wire in the wall for a 50A plug would be heavier for a 50' box-to-outlet length).

That welder likely originally came either without a power cord (if it has jumpers inside the line-terminal box for different voltages), or a 10' 10-2 w/ground, more likely. The original supplier who put the 75' on used the logic, "That's what it came with, so..."

Cut it down to 50' or less, use the balance for a heavy extension cord (w/ a multi-outlet for your heavy power tools?), and see if you miss that other 25' before spending the money. If you find you really need the range, get 100' of 8-2 w/ground, or 150+' (175 comes to mind without digging up the chart) of 6-2 w/ground.

BTW, there's a price difference between, say, 10-3 and 10-2 w/ground. As a dedicated ground is simply for earthing the machine and providing a short-circuit path long enough to trip the breaker/blow the fuse, the ground on a 10-2 can be 14 ga., saving on copper.

Steve S

You can also save quite a bit per foot on heavy duty power cord by asking for or using SJO cable versus SO cable. They are basically the same thing size-wise, but the SO is rated for 600 volts while the SJO is rated for 300 volts. The incoming voltage per leg on most welders will be nowhere near 300 volts.

SO designates "Stranded (or Service), Oil Resistant"
SJO designates "Stranded("), Junior, Oil resistant.......the junior meaning it's rated for less voltage.

Other (Sparky) Steve

Thanks all. I'll just leave 8 or 10 ft on the welder and cut a 40 ft length for the welders, making 50 in total for the Miller. Even after buying an extra outlet/plug I guess I'm still cheaper than running a 6/3 or 8/3 to the other side of my garage where I would be using the welders.