110v welder and the 3/8 bend test

[JimRB]

It isn't wiring in 30 amp breakers, it is wiring in bigger feeder wire from the breaker for less voltage drop. When I got my little Hobart 120 my friend the welder who has some of that alphabet soup certifications (yes some certifications can mean nothing) said the welder does better with a 20 amp circuit. That is not just a 20 amp breaker, that is 12 gauge copper wire instead of 14 gauge wire. I gather a 30 amp circuit is 10 gauge wire. Bigger wire is both ampacity and voltage drop.

Electrical: Building Wire - Bigger Really Is Better

And another read on power.
Electrical: Power Quality - A Power Quality Primer

 

[MossRoad]

Well, its not pushing a load from the supply... its pulling a load. At the same voltage, all a larger breaker will do is allow more amps to be drawn if needed. A larger breaker doesn't push more amps to the machine. Does that make sense?

 

[Sodo]

,,,,said the welder does better with a 20 amp circuit.

Your friend is referring to the times when you have the welder set for max power. But power setting depends on the project.

In my experience a 120v MIG may or may not pop a 15A breaker when set for 3/16" thickness. Settings for 3/16" seem to be on the hairy edge of 15A. You CAN weld a few inches at a 3/16" preset, on a 15A circuit (again, my welders, my usage). If you are setting your machine for 1/8" it won't pop a 15A circuit. For example if you're welding a brush hog deck, (my Rankin brush hog deck is 1/8"), you can do that on a 15A circuit. Certainly a 20A circuit makes it simpler but it's not a show-stopper for many light-guage repairs.

If course there are variations in supply depending on your location as Mudd has mentioned. If your supply happens to be 130v, you can get more power than if you have 110v.

 

[muddstopper]

Well, its not pushing a load from the supply... its pulling a load. At the same voltage, all a larger breaker will do is allow more amps to be drawn if needed. A larger breaker doesn't push more amps to the machine. Does that make sense?

What you say makes sense, but, if you have a 20amp breaker, all the machine can pull is 20amps before popping the breaker. Amp usage with mig can vary by adjusting the wire feed or how close you hold the gun to the weldment. VoltsxAmps=watts. The migs are 120v AC converted to provide DC V tothe machine. Wth CV the volts doing the welding shouldnt change, just the amps and watts being used. more amps, more watts, more heat. I dont have a clue as to how the electronics work inside the machine, I know they regulate the power somehow, but if the internals regulate the power being used so that no more than 20amps can be pulled from the breaker, then adding a 30amp breaker would be of little use.
Everybody says use at least a 20amp breaker to get full use of the machine capabilities, and that 15 amps will lower the welders output. And they say using a 30amp breaker will up the power output, but if the welder cant use the 30amp breaker, whats the point?

 

[MossRoad]

Exactly. 15 amp breaker will not lower the output of the welder if you're drawing less than 15 amps. If you draw more, it will pop the breaker. So, you're limiting the potential work that the machine is capable of doing if its capable of pulling more than 15 amps. You could weld heavier items with a 20 amp breaker if the welder is capable of pulling that many amps.

 

[MossRoad]

Now someone did mention voltage drop in the line from the breaker to the outlet. And that is a real, measurable thing. 15amp circuits are typically wired with thinner wire than 20 and 20s are typically wired with thinner wire than 30s. If you have long runs, you could have a voltage drop that does make a difference in the power available to the welder.

 

[CNC Dan]

I dont have a clue as to how the electronics work inside the machine, I know they regulate the power somehow, but if the internals regulate the power being used so that no more than 20amps can be pulled from the breaker, then adding a 30amp breaker would be of little use.

You can draw(pull) more than 20 amps from a 20 amp circuit breaker. For brief periods only.
And as you turn up the settings on the welder, it will draw more input current. I don't believe there is any hard and fast limit of 20 amps input current draw.

The machine is trying to control the output power, and will try to draw as much current as it needs to to do that. If you turn it way up, I believe it will dra
w more than 20 amps. And if you weld for a long time, it should trip a 20 amp circuit breaker.

 

[muddstopper]

Well, lets eliminate the wire runs and sizes. Welder sets next to breaker box, plug is wired with 8ga wire. Now, is there any benefit of using a 30amp breaker over a 20amp, and does having 30amp's availalble, is it possible to pull more amps at the mig gun than it would if it was on a 20 or 25amp breaker. Or is the welder made so it cant pull more than a specific amount of amps, reguardless of breaker size, and using a bigger breaker just fooling everybody into thinking the machine will preform better.

Let me add, if its possible to pull more amps with a bigger breaker, will this effect duty cycle?

 

[MinnesotaDaveChalmers]

Mudstopper, here is my take.

Welding manufacturers know how long a 20 amp breaker will allow a 25 amp pull (for example).

So if the machine is rated at 20% duty cycle at the welding amps that creates that draw, the manufacturer knows if the breaker will trip or not in that two minutes.

It is also known that the large inrush current for a second or so will also not trip the breaker.

Oversizing the breaker and wire just ensures you get the amps the machine is capable of - but now it definitely won't trip the breaker in two minutes.

Now if the machine has no cutoff for over temp, and the operator does not follow the duty cycle, and the oversize breaker will not trip, longer welding time is available until the unit overheats and starts to sputter.

This overheat can be done several times on welding machines until it's damaged, or just once - it's a crap shoot.

My first little mig sputtered at me pretty often on the day I finally get pissed and bought a bigger machine.
(So did the stick machine I was using that day - it was summer)

I ran that mig on an oversized breaker and an oversized extension cord - ran great that way and in the winter did not overheat.

Just my experiences - nothing more.

 

[muddstopper]

Dave, dont know why It matters, I dont own a 120v welder. I guess Roadhunters pointing out the comparison, (amps and duty cycle), between the 120v mig and one of the dual voltage machines made my mind start wondering.