I would ALWAYS put in the full 4 wires especially when you are talking
about NM or UF cable. The cost is minimal, the labor and access is
usually a bummer. If you are pulling it though conduit, I might let it
ride for a while.

In the lab at school we have a 200 amp 3 phase bus duct, they cheaped
out when building the place, ran 3 hots and a ground with no neutral. In
order to put the neutral in we would have to pull all 4 wires out, add
the neutral, pull all 5 back in. Dumb.

Grant Erwin wrote:

Alex wrote:

I am pulling a new 220V line from a power box for my new belt grinder
(20Amp 115/220V). Wiring is inside my garage and 8 gauge wires go
through conduit. San Francisco code requires 4 poles for 220V
appliances so I am using four wired inside conduit.
My question is how to wire switch and motor to four wires.
Motor wiring has 6 wires but instruction says that 3 wires go to one
pole and 3 other to another. What about ground and neutral?

Is there any good on line DIY manual for this kind of work.


4 poles would go to a dryer outlet, which has L1, L2, N, G

L1: first 220V line
L2: second 220V line
N: neutral -- voltage L1-N or L2-N is 120V
G: ground

I would never go to the expense of running 4 wires when you only need 3.
Nor do I believe that San Francisco code actually requires it, but there
are amazing things in California laws. Your motor will use L1, L2 and G,
of course.

GWE