Hi All

the house i bought has a detached garage about 20 feet from main structure. It currently has 1/2 rigid metal conduit with a single 20A circuit (12ga). I need about 13A for a table saw or router (two are never on together) and 11A for dust collection. Then enough for radio and (4x4ft fluorescent tubes).

I realize that if I were starting over I should run 3x6ga + ground and add ground rods and a sub-panel with 60A breaker in main panel. Is there anything I can do with the existing 1/2-inch rigid metal conduit to get me (at least) 2x15A

for example
- Add 2 x 12ga for total of 2x20A circuits (2 breakers in main panel)
- Add 4 x 12ga for 2x15A and 1x20A (3 breakers in main panel)
- Replace all with 8ga for total of 2x20A and 1x15A (double pole breaker in main panel and sub-panel in garage)

What size should the ground back to the main panel be? I seem to recall it can be smaller than the current carrying conductors?

If using multiple circuits back to main panel, would a shared neutral help reduce wire count?

TIA
Mark