working on it wrote:H.A. wrote:To split hairs,
The receptacle on the right is a NEMA 6-15R.
NEMA 6-30R is substantially larger and wont fit within a singlegang box.
As others stated, You need to verify the circuit feeding your garage panel is large enough to supply your new welder, PLUS whatever existing loads, lighting, appliances, etc.
It appears you have a 100amp Square-D Loadcenter, However, does not mean it is supplied by a 100amp circuit.
I forgot to acknowledge that H.A. was right, the receptacle was a 6-15R. Since I was home today, I did some more (closer) checking of the main panels and the cable/wiring leading to them. I pried and separated (very carefully) the 'tied, buried, wrapped' input wiring to the outdoor main from the output wiring to the shed and garage sub-panels. At closer inspection, I found I was wrong about the previous owner using 12ga indoor Romex going underground to those two panels. I found 8/2 cable instead. That's 8ga! The ampacity is good for 40 amps to both areas. The wire run to the shed panel is 75 feet to its 30amp breaker, and 30-32 feet to the garage panel with its 40amp breaker. After that point, the wire is only 12ga to the receptacles. Using this calculator http://www.csgnetwork.com/wiresizecalc.html, it shows that I could "get by" with only 12ga wiring (at the reduced output setting I set the welder to). If correct, I could go ahead and change one receptacle to 6-50R, and test the stick welder to the reduced setting. At worst case, the sub-panel breaker would trip (I will also check the fully-exposed 12ga wiring for elevated temperature as well). I still will have the electrician cousin consult, and check, and possibly re-wire the whole thing soon. I won't "use" the 220v welder till then, just the one "trip" test. I'll get the small 110v flux welder if I just can't wait.
I hope that was 8/2 with ground?
Dale