My guess, based on my limited experience,
is that your compressor wires to black, red
(to black and red) ground to the third screw.
The white neutral is not used.

Dryer plug and socket should work fine. Old
style, three conductor. Of course, you can
wire in a disconnect switch if you wish.

The reason they went with four wires, is to
provide a neutral for 120 volt timer and drum
motors, used in some dryers.

..
Christopher A. Young
Learn about Jesus
www.lds.org
..

On 9/4/2013 11:07 AM, stryped wrote:
I have a new 5 horse 80 gallon upright ingersol
rand compressor. I need to wire it up. My outlet I
wired years ago in hopes of having a new compressor
I ran 4 conductor cable. red,black,white, and ground.
My compressor has connections inside the pressure
switch but only three. Red and black I understand,
however do I put the white neutral on the third spot
in the switch or do I put the ground there? This is
in my detached garage with a 100 amp sub panel.

Just want to make sure it is right.

Also, I assume a dryer type plug is not a good
Idea and I need a disconnect with the wire from it
to the compressor in armor shield?

I appreciate it!