Thanks for all the info and comments. It helps with my considerations.
The detached garage is a POS built from scrap wood in the 1930s as a one car stall, one horse stall unit. I've repaired it enough to straighten it and make it a usable open front shed and can squeeze my wife's "new" 2001 Jeep Wrangler in the horse stall side.
I actually gutted a lot of the existing electric and reran 12awg from the house to and through the garage. I did use one inch PVC buried only about 12", hand dug ditch. I MIGHT be able to pull 10awg through it but there is a 90 degree bend on each end where it goes into the ground. I'd like to keep the existing 12awg line as a separate circuit.
I will be doing any and all work myself. I can't quote the NEC but otherwise I'm very experienced on home electrical systems (US Navy electrical trained) & have replaced all the accessible knob and tube in the house (the vertical runs are a problem), separating circuits, doubling the number of CBs in the box. Electric was SUPPOSEDLY upgraded to FHA requirements when my wife bought it 40 years ago, yeah, right. House was built in the 1920s.
