Adding Welder to garage

[corner27]

I bought a house last summer. It has a double detached garage, and I am thinking I'd like to get a welder and do some welding.
The house has a 100 Amp service, and a 40 amp sub panel in the garage running off the house.
If I put a 30 amp 240 breaker in, will this be enough for a small mig welder?

The other question is will this overload the house's main breaker?

Thanks,

 

[Gary S]

That depends on what you call a "small" MIG welder. My small MIG welder runs on a 20 amp 110v circuit and it handles welding anything I need to weld. I'd suggest picking out your welder first and then wiring the circuit correctly for its needs.

No, a 30 amp breaker will not overload your 100 amp panel's breaker.

 

[corner27]

I was looking at a hobart 187. It says it runs at 20.5 amp. so I would imagine a 25 or 30 amp breaker. Since the garage only has 40 amp, I will need to limit the amount of things running at the same time.

On a side note, it I was to upgrade to a 60 amp in the garage, what wire would I need to have running to the garage? Would a 60 cause an overload on the houses 100?

 

[katit]

Wire/Amperage rating will not cause overload by itself nor present danger if you have right ampacity wire/breakers. Worst can happen that if you are in fact pulling 60A out of the house and house usage at the moment above 40A - you will trip main breaker in house.

 

[sberry]

Welding with a small mig will be fine with that service, done all the time. A 30A breaker feeding a 10 wire is a tailor made circuit for a 187.

 

[70runner]

I have nearly identical situation...Hobart 187 (great welder btw) on 240/40 circuit in detached garage. IIRC, Hobart stated 30amp needed for the 187. As you said, just limit number of things running. I have a large vertical compressor and plasma, both 240v current hogs. Just have to make sure the compressor isn't running while I'm welding.

As to your wire size, it depends heavily on the run length. I ran #4 conductors in underground conduit about 150ft supplying the detached garage.

You might want to explore getting an upgrade to your main panel, to say 150amps, to reduce chance of tripping main.

 

[corner27]

I have also thought about upgrading the main panel, but I would assume that comes with a big price tag. I know they ran new wire underground, but I'm not sure if they put in thicker wire when they did this or not.

 

[sberry]

What kind of appliance in the house? All gas or all electric? Usually water heater is the main current hog not counting large air cond units or electric heat. We have had forum members here with 30A garage service and it worked. This is one of the benefits of these small wire feed units, very thrifty with power demands.

 

[corner27]

I have a gas furnace and hot water tank. Elec dryer, washer, stove, fridge, etc

 

[sberry]

You will be fine. Biggest real draw will be the dryer, change it to gas and it would be like getting an electric upgrade,,, ha Stoves really don't use much unless its a holiday with 4 burners on hi and the oven blasting on broil.

 

[corner27]

Sounds good.
I looked at my panal today, and the wire going to the garage is about 50 ft long and the wire says 8/3 on it. Is 40 amp the max I can run through it?

 

[bdog]

This is a simplified answer and a real electrician will tell you it is more involved and complicated than this and there are special rules, exceptions, etc but in a general sense the maximum current you can carry with copper wires is the following:
14 ga - 15 amps, 12 ga - 20 amps, 10 ga - 30 amps, 8 ga - 40 amps, 6 ga - 50 amps.

So with your 8/3 the max is 40 amps. You should be ok running the welder out in your shop unless you have a lot of light drawing current out there or have a compressor running or other things going on while you are welding.