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oups.com...
Hello Keith,
I am just passing by and noticed your post , I am an electrician.
I do not know what level of experiance you have so let me start with
some warnings, if you know understand what you are doing ignore the
next few lines
(re-wire DC motor to 220V)
I am not sure what you mean here D.C. is NOT a.c.! Unless there is

Thanks, M.E. Sorry for the confusion. As someone else noted, I meant Dust
Collector, not direct current. Made an assumption about the audience of that
post. The dust collector has a 110/220V motor, pre-wired for 110. I believe
it's a straightforward task to re-wire for 220. I don't believe it comes
with a 220V plug, though; I'd need to add that.

The only real problem that I see is this:
You have 30 amp double pole breaker.
You want to use 220 for *whatever*
You want to use 120 for *whatever else*
what if the 120v appliance or tool messes up and starts pulling a
higher load until it burns up ...

I was just thinking about this on the way to pick up pizza. With 10AWG wire,
I'd have a circuit capable of 30A, but the cords from all the tools are
110V/15A. (leaving out the Dust Collector for a moment). Those will plug
into 20A receptacles, so say I wire 20A receptacles on the 120V outlets. Now
suppose the planer or whatever manages to load down and wants to pull
something like 28 amps. The circuit breaker says "no problem". Could run
that way all day and it wouldn't trip. But what about that receptacle that's
rated for 20A?? Are the connections or conductors inside it going to
overheat? Might be some risk there, not to mention the tool itself like you
say. I should go look at my reference book; NEC probably doesn't allow a 20A
rated receptacle on a circuit protected to 30A.

Then there's 120V/30A receptacles. Haven't looked, but probably cost more
than the 20's. The 110V/15A plugs won't fit in them, so I'd have to change
plugs on the tools. Even then I have to consider how likely it is that I'll
have situations where the tool wants to pull more than its rated current.

The 3-wire circuit starts to look like more trouble than it's worth. It
sounded like a slick idea at first, because I have the breaker, and I'd be
able to run 3 wires + ground in my conduit. (Finished walls, and I'm not
going to tear them up, so I'll be running EMT and individual wires inside).

I am going to ask a local electrician, but starting to think about the
original plan of a simple 2-wire 20A circuit. Then go with 220V, on a
separate circuit, on the dust collector if it's needed.