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
some transformer-rectifier setup you didn't mention this just wont
work, AT ALL.You will end up in flames.Realize you are saying rewire a
?Voltage Direct Current motor to 220Voltage Alternating
Current...these are different beast.


With that 30A breaker and 10 AWG
wire, should have no problem handling the loads from a DC and air
cleaner
running, and startup surge from another tool.
O.k. that is pretty reasonable there are many appliances that run on
220VAC and use one hot and a neutral to get 120VAC and use that for the
timer, controls, or whatever. Really there is no reason to have put in
a neutral wire in if you weren't needing to use it for that very
purpose, ok you can use it for a 3way or 4way circuit, but that only
holds for small wire...think about it.
If you don't already know the transformer outside your house sends 3
wires.
Grounding is done near your house.
This is what you get fromthe transformer: L1-N-L2
L1 and L2 are the ends of the winding and N is the center tap that they
ground. It is therefore in the middle between the two legs so between
L1-N there is 120VAC and between N-L2 there is 120V and between L1-L2
there is 220VAC DIFFERENCE cause it is really all about potential
difference between points Also you might be fooled into thinking
Neutral is ground it is not . DO NOT use it as such it can be a lethal
mistake.
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 ...
The breaker would stop it huh....Nope not always, not if it didn't
exceeded the 30 amp breakers capacity.
Which is why you should run a seperate line for your 120v loads and
your 220v loads that are not related.It is just a lot safer , also
ground everything especially on a motor load, it will help reduce
staitc and noise on the line as well. In this case I would run a new
line, but I am an electrician
Oh and by the way always check your local electrical codes they are
always diffent and can sometimes surprise you!
Hth,
M.E.Farmer