Fused disconnect on welding circuit

leeko · Aug 18, 2014

Hi all,

My garage has a 20amp 220v circuit on awg12 wire, which I can't upgrade (yet). I have a couple of 220v welders (175amp mig and 180amp stick), which have been running fine on the circuit. I don't hit the top end often, and then only for short runs. I've yet to trip the breaker (yet).

I'd like to add a disconnect for the entire 220v service in the garage, so I can switch everything off when I'm not working. I have a 30amp fused safety switch which I was planning to use.

My question is related to the fuses. They're time-delay fuses, which I think is better for the welder circuit to avoid nuisance trips. But, what rating should the fuses be? The 20amp breaker and 12awg wire "tolerate" the higher current load of welding for short times, but is that the same for the fuses? I.e. they should be rated at 20amp? Or will they trip constantly while welding?

Thanks,

Lee

Gravel · Aug 18, 2014

If the disconnect is between the breaker and the receptacle it doesn't matter how big the fuses in the disconnect are.
If what i described is what you are thinking of doing, i suggest a 60 amp disconnect because it will still work fine after you upgrade the breaker and wiring.

leeko · Aug 18, 2014

Yes, it's between breaker and receptacle. Why wouldn't it matter what size the fuses are? Do you mean the fuses can be oversize because the circuit is protected by the breaker?

Thanks for the tip re: the 60 amp disconnect. I already have the 30 amp disconnect, though, and won't be upgrading the wiring any time soon.

Thanks again

Sent from my SGH-T889 using Tapatalk

Gravel · Aug 18, 2014

Exactly.
Since you already have it, it makes sense to use it.

Fused disconnect on welding circuit

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