breaker size needed for welder

[stratton]

A while ago I had an electrician wire in a subpanel box in the garage for some extra plugs and tool outlets. I mentioned that someday i wanted to get a welder. He put in a 100 amp panel box. Now that i am shopping around for a welder I noticed that the migs are anywhere from 125 to 140 amps for the size that i want. does this mean that i cant run the welder at full power?

 

[balernbud]

no, that means how many welding amps the welder puts out even a 250 amp welder can be run on a 50 amp 240 volt breaker

 

[k0ua]

A while ago I had an electrician wire in a subpanel box in the garage for some extra plugs and tool outlets. I mentioned that someday i wanted to get a welder. He put in a 100 amp panel box. Now that i am shopping around for a welder I noticed that the migs are anywhere from 125 to 140 amps for the size that i want. does this mean that i cant run the welder at full power?

Nope, you can run your welder. the 125 amp or 140 amp is the welding current not the input current. I am guessing the 125 and 140 are 120 volt input welders. You can look at the specifications for your new welder to see how much input current it would draw. The 140 amp setting would probably press a 20 amp 120volt breaker pretty hard, as in you might need a bigger one than that. The current rating of those welders is rated at about 19 or 20 volts DC. NOT 120volts AC. You might need a 25 or 30 amp breaker but your 100 amp service is enough for a lot bigger welder than what you are looking at.

James K0UA

 

[5030]

Just because he put in a 100 amp panel don't mean you have 100 amps available. It means the panel bus is rated at 100 amps.

I take it the building is contiguous to your home and the sub panel is on a split from the house panel? If so, what are the main breakers for the house panel rated at first off and what are the sub panel spit breaker rated at?

Keep in mind that most residential drops (ftom the pole to the house) are usually 200 amps or less, sometimes much less depending on the age of the dwelling and if your service has ever been upgraded.

You have to take into account household loads, fridge, lights, furnace, ac, your computer, everything and start subtracting from the service rating. You may have a lot less than you think you do.

Then ther stuff in your shop. An air compressor maybe, overhead lights, a beer fridge, dehumidifier? All pull amperage.

While not everything may be on at the same time, keep in mind that starting amperage on motors in appliances and your air compressor (if you have one are 3 times running amps).

All things to consider if adding a welder.

Just 'cause it says 100 amp don't mean it is................