Generator for welder
- Thread starter aj2n
- Start date
BIG DOOLEY
Platinum Member
I have a Northstar 10,000 watt surge/ 8000 watt continous with a 40amp 240 volt outlet.
Both welder and generator are mounted on a small trailer.
Both welder and generator are mounted on a small trailer.
joshuabardwell
Elite Member
Depends entirely on the input current required by the welder. A typical 225 amp buzzbox might have 50 amp draw at max output on AC and 35 amp draw at max output on DC (don't ask me why they're different, I just looked it up recently). 50 amps times 240 volts equals 12,000 watts. But, realistically, if you tried to run that welder on a 12k generator, it's not going to work well, because when you start the arc, there is a big rush of current, and it most likely is going to overload the generator, causing voltage to drop, and the arc is going to fizzle out.
Now, that all assumes that you are going to be running the box at 225 amps, which, granted, is pretty hot for your typical home fabrication situation. But it gives you some idea of how to proceed. Look up the specs for the welder you are working with and find the current draw at your desired rated output. Then find a generator that can provide that current reliably. If your generator is sized at double your desired output, you will probably be okay. So let's say you're going to top out around 150 amps, which is more than enough for 1/8" rod. Assuming a linear relationship between output and input amperage, that equates to 33 amps. That's 8000 watts at 240 volts. You might get away with running that on a 10k or 12k generator, but you might not. It all depends on how well the generator is able to handle the surge when you start the arc, and how adept you are at not sticking the rod when the arc is unstable.
Another thought: some welders specifically say that they should not be run off generators unless the generator makes clean power. You had best check with the manufacturer to make sure what that means before proceeding. I suspect that if you have an old transformer-based welder, it won't matter, but if you are running an inverter-based welder, that's another story. They tend to have a bunch of circuitry inside them that may not be happy running on a genny.
Hopefully, this gives you some idea on the ballpark range, though. I wouldn't even try running a 240 volt stick welder on less than a 10kW genny unless I absolutely had to. Sure, if you run 3/32" rods you can get down in the 60-90 amp (output) range, but you're really limiting yourself at that point, and you're probably not going to be happy.
joshuabardwell
Elite Member
A final thought: if you are thinking about buying a genny to run a welder, why not shift gears and buy a dedicated generator/welder. My guess is that a 10k generator is going to run you around $500 used, and bear in mind that's the absolute minimum that I'd suggest for running a stick welder. A used welder will run you at least $150-200. So you're into the project for about $700 now. If you are willing to go up to the low $1k range, and are patient, you can probably locate a used generator/welder. You'll know that it'll run the welder, because it's designed to, and it'll double as a generator when you're not burning rod.
Reyer Farms
Platinum Member
Yep, and your life will be a little simpler!
byronlj
Silver Member
I can crank up my stick welder to 225a and run it off my 40a 240v circuit . So, you are not using 12,000 watts. I have welded @ 170a using my contractor type generator 5200w and my 6300w inverter generator with no problem also. I never went above that because I didn't need to. This was also for light fabrication so not running the welder continuously. My 190 Hobart mig welder also works on these generators.
Dave
Dave
Reyer Farms
Platinum Member
The new Lincoln compact machines look very handy and miller has the wildcat 200 in addition to the tried and true blue stars. I'm not trying to tell you what to do with your money but throwing some options that may work better in the long run. The older Lincoln ac 5500 is a good lil welder and can be very reasonable. I don't know if that is an option. What are trying to accomplish with being portable?
BIG DOOLEY
Platinum Member
I typically run DC all the time with my welder.
The welder requires less amperage at full output if I remember right.
Tig mostly and on a very rare occasions stick.(rust metal or in the field and I don't want to lug around the Argon tank)
Even without the simple tig set up I have, DC it the most preferred welding choice.
If you run can run a welder on a smaller generator than the rated requirements for the welder and not blow the breaker with the in-rush current draw, you most likely are not running at the output you think you have dialed in anyway.
Good luck
The welder requires less amperage at full output if I remember right.
Tig mostly and on a very rare occasions stick.(rust metal or in the field and I don't want to lug around the Argon tank)
Even without the simple tig set up I have, DC it the most preferred welding choice.
If you run can run a welder on a smaller generator than the rated requirements for the welder and not blow the breaker with the in-rush current draw, you most likely are not running at the output you think you have dialed in anyway.
Good luck
joshuabardwell
Elite Member
Right. You're using up to 9600 watts (40 amps at 240 volts). And a wall socket is much more able to smoothly apply inrush current than an undersized genny. So you could be doubling that for very short periods of time when you strike the arc.
I can't speak to the other examples because I don't know how your output current maps to input current for your welder. I'm glad it worked for you in the end. I know a lot of people have trouble getting their arc started because the genny can't supply the inrush current even if it is nominally big enough.