Long story short, I have a 30-amp, double-pole breaker wired to 10/2 cable. Black and white to the two poles on the breaker, bare ground to the combined neutral/ground bus bar.
The shop has four 20A receptacles. Black to the "hot" side, white to the "neutral" side, and bare to the green ground screw. I was wiring them like I've wired every other receptacle in my life (all 110)... What I didn't realize was that I had a double pole breaker. Rather, I asked for a 30A breaker (since I had pulled 10-ga. wire), and never considered the ramifications of the fact that the thing he handed me was double-pole; not even as I merrily hooked it up like all the other double-pole breakers in the panel.
I just didn't think. I've done some wiring projects successfully, and I fell into the trap of thinking I knew what I was doing. I obviously didn't, and I'm very lucky that the worst consequence of this mishap was a blown ballast and a fried voltometer.
What I have is half-assed 220. I'm not sure if I could just rewire my big motors and use this with 10/2 cable (or maybe run an extra red wire) or really what my options are at this point.
Seems the easy thing is to just throw away the $60 breaker (can't return it, and I have no other use for it) and buy a 20A SINGLE POLE, then continue with the original plan, but then there's the non-trivial problem that I have cut the neutral too short to make it to the bus bar, and I already took up the slack at both ends of the run.
It's a big mess. I deserve all the "hire an electrician before you burn your house down, you moron" type comments that I'm sure will follow, but I'm *not* stupid. I just had my head up my ass. I could use some advice, on how to get it out without electrocuting myself, or burning anything down.