Sorry for the reply in this state, but I have been unable to figure out how to do “quotes” yet.
Yes. 7 spaces still unused besides the 2 double pole 50A breakers feeding the garage and the welder.
Just replace the 50’s with 100’s, replace the wire and get going.
So I could pull two #2 wires in each of the two existing conduits and elimate the need for both of the existing 8/3 w/gnd cables in there now? And not have to dig that trench again to replace the 2 small conduits with 1 big one? Example: one "hot" and neutral in one conduit, one "hot" and ground in the other conduit?
Just one of the conduits will handle two # 2 wires and supply your 100 amp service. (if you set a new ground/neutral) put the welder on the other #8’s, change the breaker to 40’s and go. I can’t imagine the welder not running on 40’s
I don't like them either but if enough advised that it was the best option at this point, I'd try some.
You talking about the breakers or the chicks?
One more thing. You could run a whole new service, and use the existing conduits, pressurize them, and get the little woman to send beer through it for those long garage stays. Just a new variant on the same problem. Gotta think outside the envelope, ya know.