When I moved into the house, the 220v was split at the subpanel to make two more 110 lines.
A number of years ago, I had some excavation done in my yard and the guy hit and broke the wire which was buried. I replaced it with 8 wire. So, from breaker box to where it exits the house is #6 (about 30 ft), then buried from the house to the garage is #8 (about 40 feet), then where it enters the garage to the subpanel is again #6 (about 15 feet).
So, that breaker should be changed to a 40amp, I guess. I never changed it because I knew I would never pull that many amps. The biggest thing I run is a table saw along with flourescent lights.
But now, I would like to run a MIG welder in the garage. I would like to use a 220v with as many amps as possible.
So I figure I would wire as follows:
1) Change the 50amp breaker in the main panel to a 40amp to account for the #8 wire.
2) In the garage, I would take the two lines that were 220v that I split into 110s and I would splice them (or come out of the subpanel with them with a higher awg) so that in addition to still being two 110s, they would also be a 220 again.
3) The 220 would go into another subpanel with a 30amp breaker.
4) From this new 30amp subpanel, I would run #10 to an outlet for the welder.
This way I would be able to use a 30amp 220v welder. I guess I could use a 40amp in the subpanel but I figure because of the distance I should step it down a little.