220V Compressor wiring

[Doug Walls]

I just bought a new air compressor, it's a Puma Model# PK-6060V & I'm a little confused on wiring it up!


The compressor has a 3HP 3440 RPM Motor, it's a F56H frame (compressor duty) capacitor start. Voltage is 115/208 – 230 Amperage is 29.40/16.20 – 14.70
The motor is factory wired for 230V from the motor side of the pressure switch with 12 gauge SJT cord, The line side is not wired.


Here's where my confusion comes in: The wiring instructions states to use 10 gauge wires for the line side of the pressure switch! Why would they suggest using 10ga. wire before the switch & 12ga. after it?
Also according to the wiring diagram inside the cover for the pressure switch it looks like it's only rated for 12A. at 240V / 2HP! The pressure switch is a LEFOO model# LF10-4H 150 psi limit.

The compressor is only 20' from a sub-panel in my garage so I originally planed to run a 220V 20A line to a two pole disconnect switch mounted on the wall next to the compressor, then wire the switch & compressor with 12 gauge SOOW cable.

[Chip Lindley]

Doug, perhaps the compressor people are recommending 10ga wire to compensate for a long run from the breaker, just in case. Smaller gauge wire can be specified for making connections (as inside a contactor box) on very short runs--thus your 12ga wiring from the switch to motor.

Your compressor motor should run fine on 12ga wiring with a 14.7A 230V motor on only a 20 ft. run of wire. The pressure switch contacts are on the smallish side, but I suppose factory knows best. (or, they calculate the pressure switch should not burn out before the warranty expires) The 20A circuit would be correct for a 3hp 230v motor.

My 5hp 60gal. Quincy came wired to use the pressure switch as the unit's on/off. The pressure switch contacts were DPST, but one side of the 230v line ran through both contacts. (to prolong the life of the contacts, I suppose) The other side of the 230v was always hot, directly wired to the motor. I added a Square D 30A magnetic motor starter. Now the pressure sw. contacts only activate the 230v starter coil, rather than carry the full 21A motor load.

Undersized pressure switches are notorious for burnt contacts that stick closed and will not allow the motor to shut off at the pressure limit. When you must replace yours, look for a heavier switch with 20A- or 25A-rated contacts, but still the same pressure ratings.

[Doug Walls]

Doug, perhaps the compressor people are recommending 10ga wire to compensate for a long run from the breaker
That's kind of what I thought also! I wasn't really sure on the specs of a “Compressor Duty” motor, I thought It may have a higher amp starting load than a regular 3HP Motor. They state it as a 3HP (running) but also shows it as a 6HP (peak)


Your compressor motor should run fine on 12ga wiring with a 14.7A 230V motor on only a 20 ft. run of wire. The 20A circuit would be correct for a 3hp 230v motor.
Thanks for the info!