I'm planning to install a subpanel in a separate workshop, about 100 feet (as the wire flies) from my house's main 100A panel. I'll have a 15A 220 circuit for machinery, a 20A 110V circuit for lighting and outlets, and a 40A 220V breaker that feeds a rotary phase converter, powering a 3HP 3phase 220V jointer. The phase converter is rated for a 10HP total load, so it's to be wired to a 40A circuit, but I'm sure I'm not pulling anywhere it's full capacity since I'm only running the 3hp jointer. The plate on the jointer says it's full load current is 8A at 220V.
So I was planning to run H-H-N THWN #6 Cu in 1" conduit from a 50 breaker on the main panel to a 125A 8-space panel in the shed. That gives me less than 3% voltage drop over the 100' half circuit distance. I'll try to get a length of sch. 80 for the exposed part of the run, going into the shed. Otherwise it's sch. 40 (the only thing HD carries
I'll put a grounding rod outside the shed, with a #8 conductor to the ground bar in the box. I'm leaning towards bonding the ground and neutral bars in the subpanel box, and only running the three conductors to the main panel, since there are no other metallic connections to the shed, and I can't imagine any in the future (this is a semi-temporary workshop until I build a barn for a permanent one- or two-man woodworking shop).
How does this sound? Is the 50A feeder sufficient for those loads? (I don't know whether to calculate a 3-phase 220V motor plate with a 8A load rating differently than single-phase motor plates.) Is it ok to have the 110V receptacles and lighting on the same branch circuit? (the shed currently has all that wiring run, and fed by a roll of 12-2 romex that the previous owner ran across the yard and plugged into an outlet outside the house.
So if I can leave that stuff wired, and tie it into the subpanel as a single circuit that would save a lot of time/money.
Thanks for your input.