Quality and Service Since 1936

How to Wire a Pressure Switch for Air Compressors

A problem General Air Products' service representatives see on a regular basis is incorrect wiring at installation. Often times, out of habit, electricians or installers wire directly to the compressor motor. DO NOT WIRE DIRECTLY TO THE MOTOR. In a fire protection air compressor the pressure switch is the brain that tells the compressor when to turn on and turn off and the brain needs power.

If you bring power directly to the motor or if you wire to the pressure switch incorrectly (most commonly done by doubling up on the motor contacts instead of using the line contacts) the compressor will run continuously. Once the system is full the compressor will continue to run and the safety relief valve will start popping.

How to Video: Properly Wire your Air Compressor's Pressure Switch

The video below speaks to these problems and aims to demonstrate the correct way to wire to a pressure switch. If you have any questions please feel free to comment below, email us or call one of our fire protection air compressor experts at 800-345-8207.

If you need information on adjusting a pressure switch on a General Air Products air compressor please click here. If you are looking for information on how to change the motor voltage on a General Air Products air compressor please visit our Wiring Guide page.

3 comment on “How to Wire a Pressure Switch for Air Compressors”

  • Fred crane

    Hi i bought a 2 hp single phase motor plus its connected to a dol switch plugged it in mains runs fine .My old motor was connected to the pressure swich to motor how do i connect the old items to the d.o.l regards fred.

    • ray

      For questions like this I suggest you contact our technical support through our primary web site - www.generalairproducts.com

  • sd

    Great post! Very informative!

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