What size generator to run stick welder?

[ckirklen]

This was the hardest answer to find: what size generator do I need to run a stick welder when I have a remote project like a fence repair?

I saw lots of anecdotal data like “you’ll need at least 10kW to run a stick welder”, yet the Hobart Champion 145 welder/generator Only provides 4000 watts continuous.Even the Lincoln Electric site states at least 10kW are required. Then there’s Watts required = volts * amps, which leads me to believe I’d need only 120 * 220 = 2640 watts, which sounds like a wimpy generator. Very confusing to a non-EE.

So found a deal at Costco on a Firman gen (assembled in AZ) with 7500W continuous and 9500 surge for a great price and the welds I did on a fence with my cracker box stick welder - even at 120 amps on 110v - were easily as pretty as the ones made with the Bobcat 250 I had rented before buying the genny.

i was welding cleats on 1/8” metal posts using 1/8” E6013 rods at 120A on 110v (only because I didn’t have the right plug for 220v off that generator).

So my contribution is that in the case of a dual-voltage cracker box stick welder at 120A, if you have a generator that puts out 7500W continuous, you’re gtg! Maybe you can get by on less, but not seeing the need for 10kW for farm use.

My goal was to not have to buy TOO big a genny ($$$) but enough to get the job done. Hope that’s useful to the next “me” asking this question.

 

[handgun357]

Check your math ... FYI

 

[jhfmedic1]

A lot of people get confused about electrical requirements. When I hear someone say "I have a 210 amp wire feed welder" they need to realize that, their welder's amperage is calculated at their welder's transformer/inverter's design voltage. They don't require 210 amps at what ever the power from the wall or generator that the welder is plugged into (120 or 240 volts). You need to calculate the watts needed to produce the power the welder will need to use to make your welder run at it's selected amperage. So if your welder's transformer or inverter is rated at 37 volts and your welder is set on 100 amps to weld, you need 37 (volts) x 100 (amps) = 3700 watts (that would be the bare minimum wattage needed to run just the transformer or inverter - you'll still need a bit more than that to power the wire feed drive motor, circuit boards, solenoid gas valve, etc) so a 4000 watt generator would work in that situation. If they needed to weld at full power 37 (volts) x 210 (amps) = 7770 watts would be needed - an 8000 watt generator. So your welder can work and weld with a smaller generator when it is set at lower amp settings but only up to what the wattage is that is available from your generator. Hope that helps out.

 

[Volp]

I am running a stick welder from my 7000 watt generator with no problems. It is a 220volt as it is the common tension in Sweden and the rest of Europe. I also use a gasless MIG on the same generator but that uses less power.

 

[aussiebushman]

If you are using an Inverter welder, you will find a 6 KVA generator adequate, but an 8 KVA will be better. Even running an old-style welder the 8 did the job, though it did struggle.

 

[handgun357]

This was the hardest answer to find: what size generator do I need to run a stick welder when I have a remote project like a fence repair?

I saw lots of anecdotal data like “you’ll need at least 10kW to run a stick welder”, yet the Hobart Champion 145 welder/generator Only provides 4000 watts continuous.Even the Lincoln Electric site states at least 10kW are required. Then there’s Watts required = volts * amps, which leads me to believe I’d need only 120 * 220 = 2640 watts, which sounds like a wimpy generator. Very confusing to a non-EE.

So found a deal at Costco on a Firman gen (assembled in AZ) with 7500W continuous and 9500 surge for a great price and the welds I did on a fence with my cracker box stick welder - even at 120 amps on 110v - were easily as pretty as the ones made with the Bobcat 250 I had rented before buying the genny.

i was welding cleats on 1/8” metal posts using 1/8” E6013 rods at 120A on 110v (only because I didn’t have the right plug for 220v off that generator).

So my contribution is that in the case of a dual-voltage cracker box stick welder at 120A, if you have a generator that puts out 7500W continuous, you’re gtg! Maybe you can get by on less, but not seeing the need for 10kW for farm use.

My goal was to not have to buy TOO big a genny ($$$) but enough to get the job done. Hope that’s useful to the next “me” asking this question.

A lot of people get confused about electrical requirements. When I hear someone say "I have a 210 amp wire feed welder" they need to realize that, their welder's amperage is calculated at their welder's transformer/inverter's design voltage. They don't require 210 amps at what ever the power from the wall or generator that the welder is plugged into (120 or 240 volts). You need to calculate the watts needed to produce the power the welder will need to use to make your welder run at it's selected amperage. So if your welder's transformer or inverter is rated at 37 volts and your welder is set on 100 amps to weld, you need 37 (volts) x 100 (amps) = 3700 watts (that would be the bare minimum wattage needed to run just the transformer or inverter - you'll still need a bit more than that to power the wire feed drive motor, circuit boards, solenoid gas valve, etc) so a 4000 watt generator would work in that situation. If they needed to weld at full power 37 (volts) x 210 (amps) = 7770 watts would be needed - an 8000 watt generator. So your welder can work and weld with a smaller generator when it is set at lower amp settings but only up to what the wattage is that is available from your generator. Hope that helps out.

120 x 240 = 26400 watts...
The only generators that have a 50 or 60 amp receptacle, that I have found are 9k and above...
I use a 10k.

 

[mr_puddles]

Power = I x E;
Wattage = current x voltage;
so take the amperage DRAW (from the data plate on your welder) multiplied by 220 or 230 or 240 nominal volts to get the minimal watts needed. Remember to add about 50% for the fact that a stick welder is an inductive load and has a huge inrush current at arc startup. You wont be running any kind of useful welder on a 2640 watt genset, but both your arithmetic and logic are incorrect anyway.

Also, how many watts a Hobart Champion puts out, and how many amps it WELDS at are two different functions.

You CAN run a small inverter welder off of a moderately sized generator, as they only draw about half the amperage of a comparable transformer based welder.

 

[aussiebushman]

Well there are certainly smarter guys around than me, but my 8KVA generator (6500W continuous) has no trouble at all driving a Rossi Inverter welder at almost any power setting. The old transformer unit I used to use struggled a bit, but it still did the job. No way would I change from the Rossi - great little unit and by adjusting the power and/or reversing the lead polarity, it will weld thin stuff like mudguards as well as much heavier steel

 

[PILOON]

One important aspect is that you do not want to run you generator at max ratings.
Never mind the quoted surge or peak, that is for motor start up which only lasts for a few seconds.
I'd personally want to aim at about 75% of the rating remembering that when you touch your stick to start a weld you are essentially creating a near short.
Were U to have an amp meter on the input you'd sure see the surges on the 220 input.

 

[ericingreenbrier]

This was the hardest answer to find: what size generator do I need to run a stick welder when I have a remote project like a fence repair?

I saw lots of anecdotal data like “you’ll need at least 10kW to run a stick welder”, yet the Hobart Champion 145 welder/generator Only provides 4000 watts continuous.Even the Lincoln Electric site states at least 10kW are required. Then there’s Watts required = volts * amps, which leads me to believe I’d need only 120 * 220 = 2640 watts, which sounds like a wimpy generator. Very confusing to a non-EE.

So found a deal at Costco on a Firman gen (assembled in AZ) with 7500W continuous and 9500 surge for a great price and the welds I did on a fence with my cracker box stick welder - even at 120 amps on 110v - were easily as pretty as the ones made with the Bobcat 250 I had rented before buying the genny.

i was welding cleats on 1/8” metal posts using 1/8” E6013 rods at 120A on 110v (only because I didn’t have the right plug for 220v off that generator).

So my contribution is that in the case of a dual-voltage cracker box stick welder at 120A, if you have a generator that puts out 7500W continuous, you’re gtg! Maybe you can get by on less, but not seeing the need for 10kW for farm use.

My goal was to not have to buy TOO big a genny ($$$) but enough to get the job done. Hope that’s useful to the next “me” asking this question.

So in the big scheme of things it’s easy to misunderstand what amperage means in the consumption electricity. All you are powering is the transformer. Wattage draws are what is important but not exclusive to use. I have a 2100 amp amp genmaker and it pushes just as well as my 8750 amp genmaker. Duty cycle is important if you are using constantly such as commercial use. I hope this confuses you as much as it did me while writing it. I know what I’m talking about but not always able to put it up words. ?

 

[kayco53]

I would start by looking at the back of the machine what its power requirements are. Not much bearing on the output you are welding with. When you find those numbers like amps at what voltage. Do the math and get it in watts. Volts x amps equal watts. The n find a gennie a bit bigger. When you strike the arc it is a big load. If the gennie is struggling the weld will suffer. Watch a big machine with a heavy load work when striking arc or gouging. Just to get the idea. Even a buzzbox should be about 8000 watts. 35amps x 220 volts = 7700watts

 

[mathuranatha]

30 years ago I used to get an old 2.5kva generator to run 2.00 mm rods by turning up the revs . in recent years my 3kva will run 2mm rods on a inverter welder once its warm [stalls if not warm when I strike the arc] . Duty cycle on the small generators is low though - get very hot penetration better with 1.6mm rods

 

[Ken Kegris]

I have a Miller 252 Mig which I can run off a 8750 predator Gen set. You must remember if you have a 4000 watt unit its actually about a 3750 and that will be both legs, You only get 1/2 the wattage on 120 volt. Go 240 if at all possible. I have a PTO 15000 and when using the old tombstone Lincoln and you can here the Gov kick in on the tractor. I have 4 gen sets and I repair them on occasion. I also have a bob cat 250 and that is 9600/10000 watt and will run all the electric welders I have. I also changed the plug to the 50 amp 4 prong on the 8750 so i can hook all of them up to the house. And I Have a adapter cord for the welder for the one that need it. I put welder receptables and the 50 amp 4 prong on all my gen sets so I dont have to hunt the adapter.

 

[joea]

This was the hardest answer to find: what size generator do I need to run a stick welder when I have a remote project like a fence repair?

I saw lots of anecdotal data like “you’ll need at least 10kW to run a stick welder”, yet the Hobart Champion 145 welder/generator Only provides 4000 watts continuous.Even the Lincoln Electric site states at least 10kW are required. Then there’s Watts required = volts * amps, which leads me to believe I’d need only 120 * 220 = 2640 watts, which sounds like a wimpy generator. Very confusing to a non-EE.

So found a deal at Costco on a Firman gen (assembled in AZ) with 7500W continuous and 9500 surge for a great price and the welds I did on a fence with my cracker box stick welder - even at 120 amps on 110v - were easily as pretty as the ones made with the Bobcat 250 I had rented before buying the genny.

i was welding cleats on 1/8” metal posts using 1/8” E6013 rods at 120A on 110v (only because I didn’t have the right plug for 220v off that generator).

So my contribution is that in the case of a dual-voltage cracker box stick welder at 120A, if you have a generator that puts out 7500W continuous, you’re gtg! Maybe you can get by on less, but not seeing the need for 10kW for farm use.

My goal was to not have to buy TOO big a genny ($$$) but enough to get the job done. Hope that’s useful to the next “me” asking this question.

I'd say, the sure way, is to read the tag on the welder that shows what amps in needs at what voltage. Then amps x volts = watts.

I got a Hobart that says 20 or 25 amps and 115 volts. Now that's the breaker size, not what it actually uses. Even so that under 3,000 W.
Got a Miller that says, like 35 amps at 115, which is a 4025 W. @ 120v that's 4200.

Generally the 230/240V rating for amps is half that of the 115/120 rating, so the watts come out the same.

 

[CADplans]

AND, as always,, the proof is in the pudding,,,
Lets make some pudding,,

A friend came over, back in 1995,, and wanted to build a trailer.
The trailer was going to haul an old military truck,, single rear axle,, etc,,
The truck was bigger than a 1 ton dump truck.

Anyways, he had a generator, 4500 watts output (not "surge")
He borrowed my Miller Thunderbolt 225, AC welder,, and plugged the welder into his generator.

He welded the trailer together with 1/8" rod,, 6011 and some 7018, but, mostly 6011.

After completion, he hauled the truck from Virginia to the west coast,, and nothing broke.

So, the best way to determine how much generator is needed is to try the welder out.

 

[Lis2323]

AND, as always,, the proof is in the pudding,,,
Lets make some pudding,,

A friend came over, back in 1995,, and wanted to build a trailer.
The trailer was going to haul an old military truck,, single rear axle,, etc,,
The truck was bigger than a 1 ton dump truck.

Anyways, he had a generator, 4500 watts output (not "surge")
He borrowed my Miller Thunderbolt 225, AC welder,, and plugged the welder into his generator.

He welded the trailer together with 1/8" rod,, 6011 and some 7018, but, mostly 6011.

After completion, he hauled the truck from Virginia to the west coast,, and nothing broke.

So, the best way to determine how much generator is needed is to try the welder out.

wow talk about sidestepping the important stuff with a long winded story.

tell us about the pudding. Good? Bad? 28 years old and unsure of its “Best Before” date?

 

[aussiebushman]

If you are using an Inverter welder, you will find a 6 KVA generator adequate, but an 8 KVA will be better. Even running an old-style welder the 8 did the job, though it did struggle.

I agree
I use an 8KVA generator that performs well. You might get by with a 6KVA but it will not like it

 

[laabk2]

When it comes to generators, I have found that if through all my calculations I need one that has a X watts output, I always go over what I need because it ends up being less expensive to purchase one that has more output because you can use it to do fit your need plus other things at the same time or you may get a bigger welder later.

 

[aircommuter]

Like someone else said welders are inductive load and generators are typically rated at resistive load. That’s where power factor comes into play.

 

[tooler]

I am a pretty experienced welder. I once tried to weld with a Lincoln gasoline powered welder that was also a 4kw generator. I could not do it with 1/8'' rods that I would normally use at around 140 amps. It was OK with 3/32 and 1/16'' rods. I used to use a tractor driven welder and it would make a 35hp gas tractor belch when the arc was struck.