Tom & Sparky,
Thanks very much. Tom, I see that 225-30 is the pertinent requirement. My situation does not fit any of the exceptions. And your point about ground rods is well taken.
Sparky, no animals in the barn. It's more a storage area for boat, tractor, etc. I also thought about animals & ground currents.
Your thought on Sec 220 & load calcs is right on; I wouldn't install a new raceway & feeder until I got an idea of how the mother-in-law unit would be set up (HVAC load, kitchenette?). Although the MIL unit is "just a thought" right now, I want the client to be aware that the upgrade we're talking about will not give them the power for the apartment, IF they ever do it.
Work safe,
Cliff
