Wring for Lincoln Power Mig Welder

vstoyko

I just purchased a Lincoln Power Mig welder model 140C that Lincoln advertises as follows: “Wide 30-140 amp welding output range is the highest output in 120 volt input power welder class.”

In the operator's manual the requirement for the advertised maximum output states: "In order to utilize the maximum output capability of the machine, a branch circuit capable of 25 amps at 120 volts, 60 Hertz is required". The manual also states the recommended input fuse size is a 20 amp breaker and recommended input amps are 20.

The design of the Power Mig 140C type 5-15P power cord input does not provide for 25 amps at 120 volts because no 25 amp receptacle exists where a type 5-15P power cord will plug into it. However it will plug into a 20 amp receptacle. It's not possible to obtain a 25 amp breaker or a 25 amp (or larger amperage) receptacle that matches the 5-15P power cord. Beyond 20 amps a 30 amp circuit is the next highest circuit according to industry practice.

I certainly would appreciate any suggestions or insight in how to safely and legally obtain the advertised maximum output of my new welder without modifying the welder's NEMA Type 5-15P power cord.

Speedy Petey

You would definitely need a 30A/120v circuit for this. Even that is technically non-complaint since it would violate the individual load rating of 80%.

DO they give an advice on how to obtain this 25A/120v input? Such as changing the cord set?

There is NO WAY you will be able to safely and legally obtain a 25A input with typical 15 or 20A receptacles and circuits.

I gotta ask, why didn't you just get a 240v welder???

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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

InPhase277

I haven't wired many circuits for 120 V welders, and when I did, I just used a 20 A receptacle on a 20 A circuit. Speedy, do you think that since we can up size the OCP to 200% of the supply conductor ampacity that this might also translate to the dedicated receptacle for the circuit? I mean, can we put a 20 A receptacle on a 25 A breaker if we are trying to be in accordance with 630.12? I want to give a tentative "yes", but I'm just not that familiar with it.

Speedy Petey

All I can say is I NEVER apply Art's 430 & 630 in a residential setting.

IMO we are wiring a receptacle, NOT a welder. Who is to say what the next homeowner will plug in? A kiln perhaps.....

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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

MgMopar

My suggestion would be to use wire able to handle the 30 amp but install a breaker and plug for the 20 amps. Easer to upgrade latter. If you have a problem then the choice would be your. I would upgrade outlet and the power cord on the unit to the units input capability. However you may not run into a issue with the 20 amp plug unless you plan to use max output for a duration.

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Mgmopar

Stubbie

Yours is rated 20 amps AC volts input for 90 amps at 19.5 volts DC in order to hold 20% duty cycle.. Your duty cycle is 20% at rated output which means you can weld continuously for 2 minutes out of a 10 minute period. In other words if you strike an arc and weld continuously for 2 minutes (unlikely) your welder must cool for the next 8 minutes. There is usually duty cycle protection with a thermal overload that will shut the welder off if you exceed duty cycle. It will reset when the welder cools enough. What all this means is if I turn the output voltage knob to around 19-20 volts dc I will pull 20 input amps. Some knobs will have amps so turning to 90 amps dc output will pull 20 amps ac input. Going above 90 amps output will draw more than 20 amps input and decrease your duty cycle. The welder is designed to weld from the minimum setting up to the rated settings all metal types and thickness as advertised. The need to provide a 25 amp circuit should not be required.
In order to supply the welder with a 25 amp branch circuit and keep your present supply cord you would need to utilize NEC 630.11(A) and NEC 630.12(A) and the exception in NEC 210.21 (B). In your case if you supply the welder with 12 awg you would simply increase the breaker to 25 amps much like we do with motors. Using 630.11 you could actually supply your welder with 14 awg as for a 20% duty cycle welder you can reduce the ampacity of the conductors by a factor of 45% of the nameplate input amps which is usually the rated current in your case 20 amps. Using 210.21.(B) allows you to keep your existing power cord even though your breaker is 25 amps. This is all because of duty cycle and being only 20% your welder will not allow the wire to get to hot enough to damage it before it shuts down.

However welding at over 90 amps rated output reduces your duty cycle below 20% by some margin. So at 140 amps max. (well above rated output) your duty cycle is likely to be somewhere around 10% or less. You also have an increase in input amperage somewhere between 20 and 25 amps. So you need a 25 amp breaker in order to weld at max. settings. This allows the inrush current when you strike your arc and the welder set at max.from tripping the breaker if it were to small. Plus more input amperage flows at settings above rated output current. Much like what happens with motors during start up. The internal circuit breaker of the welder will shut the welder down based on the duty cycle your welding at as it is a thermal preset. Low duty cycle means the welder gets hotter faster so the branch circuit conductors will not have time to get hot enough to be damaged before the welder shuts down if you exceed the duty cycle.

Hope this helps

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" One nice thing about the NEC articles ... you have lots of choices"

Stubbie

kbsparky

Why not? The Code makes no distinction on whether you are dealing with a residential situation or not.

Stubbie correctly pointed out that section 630.12 allows for upsizing of overcurrent protection to the sizes specified by the manufacturer.

We are held bound by the conditions of section 110.3 regarding manufacturer's instructions and listings. This does not change when other restrictions are placed on electrical installations. Upsizing of overcurrent protection where warranted is no exception.

Speedy Petey

Obviously, but I feel this way for the reason I mentioned.

You are NOT "wiring a welder". In this case he is installing a receptacle in a residential garage. It is MY OPINION that this is simply a receptacle, NOT a means of disconnect for a welder.

What if this were a typical 50A stick welder? He wires it according to Art630 with smaller than #8 let's say.
Now, 2 months later he gets a better job and has to move. Of course he brings his welder, but the new owner has a kiln that draws 40A ALL DAY long.
Hey look. There is the perfect RECEPTACLE right there for the kiln.

Like I said, this is my opinion and I don't expect everyone or anyone to agree.

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Sometimes I feel like if I answer any more questions it is like someone trying to climb over a fence to jump off a bridge and me giving them a boost.

wirenut1110

How about a 5-30 P & R, #10 wire on a 30 amp breaker. Maybe that will cover the bases.

InPhase277

I feel so cheated...

InPhase277

That would solve the issue at his place, but it isn't very convenient when he drives down to grandma's with it to repair a handrail.

theatretch85

How about an adapter cable to drop the plug down to a 15 amp Edison? Wouldn't be able to use the full capacity of the welder, and that's the plug it came with (from what I am understanding so far). Any attempt to draw more than the circuit he plugs into can handle, it would trip the breaker there by protecting the wires in the wall. He can use the welder to the full capacity with the 5-30 plugged into the proper circuit, and limited capacity plugged into a 15 or 20 amp circuit using an adaptor.

I have a heavy duty 12 gauge cord in the garage that has a quad outlet box on the end, with a 20 amp twist lock (L5-20P) on the supply side which plugs into its own outlet on the wall. I also have an adaptor to a 15 amp Edison to be able to use it outside of the garage as a standard extension cord. Granted at that point the 20 amp interconnects seem to be a bit overkill, but this would usually be a temporary situation.

I'm assuming the same logic should apply here in the Op's situation.

Stubbie

You forgot to make your post in "bold" and "capitalized" where you suggested using Art. 630. You will not get credit here if my tired little eyes overlook the obvious at 3 in the morning........

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" One nice thing about the NEC articles ... you have lots of choices"

Stubbie

pcampbell

20 amp will be fine. How far from the panel will your outlet be?

Bondo

Ayuh,... I've got that Welder,...

I've been running it plugged into a standard wall socket for Years now,.... No Problems....