I have a detached garage with a 40 amp sub panel. All 12 slots are used.

I'd like to get a small MIG welder for occasional projects, but don't have suitable power. The only 230 circuit in the panel is for the mini-split AC compressor. Is there such a thing (or is it legal/code) to put an "A-B" switch on that circuit so that only the AC circuit or the welder outlet would be hot at any given time?

If not, I may need to get a second meter and come straight off the transformer in my yard to a new panel.

Thanks

If your panel can accomodate 1/2 height breakers and an extra circuit. Just install 2 1/2 height breakers on 120v circuits to free up 2 slots next to each other. Install a new 220v breaker/circuit with an outlet for the welder. Use appropriate size wire and breaker for the welder.

Turn the AC off, when using the welder. Worst that happens if you forget is the 40 amp feed breaker to the sub panel trips.

I'm pretty sure my panel is not rated for tandem breakers, at least if one wants to stay within code.

I guess another option is to go with a dual voltage model and take it down to my storage garage (not far down the driveway) if I needed to work on something that needs all the amps. I'd probably use it out on the concrete aprons anyway to avoid the mess and gassing myself in the garage.

Maybe something like this?


https://www.lincolnelectric.co...95-1(LincolnElectric)

I don't know about codes in your area. But yes you could get a transfer switch and install it upstream of the sub panel and have it switch all power coming in from the subpanel, to another say breaker in it's own box (that supplies power to your welder's outlet). I use these manual turn transfer switches all day long in both 50 and 100 amp panels.

What if I took the output from the current 230v air conditioner circuit and ran it to one of these:

https://www.homedepot.com/p/Le...Brown-1288/301447057

Switch the output between AC or welder, but not both at the same time.

That switch from HD sounds like the perfect solution.

Sounds like a perfect scenario to find an honest local electrician and hire him to help you out.

There are dudes out there that really know the business and how to do things properly.