I'm looking for some direction here. I have a detached garage that already has power supplied to it, and the structure is divided into garage space and a woodworking shop by a partition wall. The garage space is all exposed joists, beams, and studs, but the shop area is all finished. The panel is in the garage on an unfinished wall. I want to run a 20A 230V circuit to the partition wall for a single 230 receptacle, and an electrician has told me there's enough spare amperage to run the circuit. I'd have a run of about 15' to the wall, and then over a few more feet to drop it down the wall (the top of the wall is also exposed in the garage side, but is finished with OSB).
I spent some time as an apprentice electrician about a decade ago, so I have the tools and confidence, a healthy respect for the lethality of electricity, can generally read and understand NEC code citations, and I'm an anal retentive perfectionist who doesn't want to get sued or have anyone get killed.
So these are my questions:
Should I use THHN in PVC rather than NM cable? If THHN, could I make a run up the wall and across the joists into a junction box, and then run NM down the wall?
What's considered "workmanlike" practice when running conduit up studs and across / parallel to joists?
I'm planning to use 12 gauge conductors for a 20A circuit - I'm under the impression this is what's advised? A dust collector is the only thing that'll be running on this circuit.