Hello,

I'm about ready to start drafting a wiring diagram for my controller, but one question I can't settle after many evenings of research is whether to run 2x 20amp circuits from the garage subpanel, or a single 30 amp circuit that can run everything.

Some of my considerations:
-I have plenty of 12awg wire so running 2x 20amp circuits would be significantly cheaper
-I have read that separate mains circuit for the VFD can reduce noise/EMI
-I've also read about avoiding ground loops: as far as I can tell, having separate circuits would create a workshop-size ground loop, as both the spindle and steppers/machine frame are conductively mounted to the same chassis and would be grounded to their separate circuits. Unless: I grounded the spindle to the CNC controller mains feed instead of the VFD mains feed, but that seems kind of weird.
-my control PC is an older desktop PC and monitor, both of which can run on 240v. This could be ran from the controller circuit, or I could put it on the normal shop 120v circuit.
-I'm planning on full implementation of EMI filters and ferrite toroids, as well as enclosure layout to separate AC voltage, high current motor circuits, and logic circuits
-Having a single circuit on which everything runs seems necessary for true single point star grounding, which seems to be highly recommended. This is apparently in direct contradiction with the advice for separate circuits for controller and VFD, which would create multiple supply grounds.

Additional related questions:
1. I bought a giant 24"x16"x10" enclosure for the controller, thinking the VFD would be inside it. With good layout, emi filters and ferrites, should I still use a separate enclosure for the VFD?
2. If i run 2 separate circuits and they're in separate conduits, do the conduits really need to be separated from each other, i.e. not running parallel along the walls?
3. More theoretically, it seems there's two rivaling philosophies: equi-potential grounding where all metallic components are grounded to each other including both ends of cable shields, and, "single drain" where shields are only grounded at the controller/supply end. How do I choose between them when electrical engineers seem to disagree?

So many questions! Sorry. This has been one of the more difficult topics to get to the bottom of, so would appreciate any advice.
(my build thread is over in DIY Metalworking Machines but thought this warranted a separate post)

Cheers