On Fri, 10 Aug 2007 16:47:05 -0600, Chris Friesen
wrote:

Lew Hodgett wrote:

BTW, Lew's rule for shop wiring:

#12 AWG for all 1Pole(120V) circuits and #10AWG for all 2Pole(240V)
circuits.

I agree that it makes sense to wire a shop with 20A circuits for
receptacles. Just gives a bit of leeway if you plug in a couple things
onto one circuit.

However, I think that wiring all the 240V circuits with #10 is overkill
given that it costs significantly more than #12. How many people have
5HP tools in their home shop? I have one 30A outlet for an electric
heater and a future welder. All the rest of my 240V outlets are 20A.

I do think it's a good idea for critical large items (compressor and
dust collector) get their own circuits. Most of the others (tablesaw,
planer, jointer, bandsaw) could realistically share a circuit or two in
a home shop since usually only one will be in use at any given time.

Chris

I know in home shops it is usually a non issue but factor in distance
from the panel when determining wire size. In my opinion I would never
put in less than 12g on 120 and 10g on 240v service. The cost is
minimal and downsizing breakers if critical is ok but never step over
your wire size.
When computing amp load just consider how many or what machines will
be running at the same time on the same circuit.
Never wire a machine without a ground. 240 volt motors only require
two hot legs but always ground as well. 120 volt service requires a
hot leg and a neutral PLUS the ground. Neutral and ground should never
be the same!
With 3 phase service any 240 motor will run fine with one high leg and
one low or two low legs but still ground the machine.
and there you have my $.02 worth.