Looks like a power upgrade for the house might be coming up...we have an outdated 100 amp service panel, and it looks like we'll be able to get it upgraded in the near future. (Time to replace the worn-out HVAC system with something a bit more efficient, and the power upgrade would be part of the project.) In the process, I'm hoping to add the power my shop has been lacking. (I'm currently running the whole shop on two 15 amp 110v circuits, one of which is shared with the washer and gas dryer.)
I doubt I'll be able to swing getting all the wiring run, but I'd like to get a sufficient subpanel in the shop for current and future needs. That would include 110v and 220v circuits.
I think ideally I'd want four 220v circuits and four 110v circuits. I figure the biggest simultaneous load I'd have in the future (after some serious tool upgrades) would be something like this:
Compressor 5hp 30 amps
Dust Collector 5hp 30 amps
Lathe 3hp 20 amps
Lighting 15 amps
Bench Power 30 amps (two 15 amp circuits)
How do I go about figuring out how big of panel to install in the garage? Is it as simple as adding up the amperage I anticipate using (with some wiggle room factored in)? Am I really looking at needing a 125 amp -- or bigger -- panel? And would this number be added to the total needed for the main house panel? In other words, say the house needs a 200 amp panel, would we now need a 325 to 400 amp panel to accommodate the subpanel in the garage?
Thanks for any advice -