Understanding Your Air Compressor Wiring Issue

When dealing with a single phase 220 air compressor, proper wiring is critical. In your case, you have a 3-wire solid copper wire configuration (white, black, and bare) and have wired the white and black as hot 110V each, with the bare wire going to ground. When you turn on the compressor, it just hums—indicating a problem with start-up or operation. Here, we will help you troubleshoot and correct the issue.

Check Your Voltage Supply

First and foremost, ensure that your voltage supply is 220V. A 220V compressor requires a 220V supply. The configuration of the compressor you have (with a running capacitor and/or a start capacitor) necessitates a proper 220V circuit. If you find that your supply is from a 120V breaker, it will not be sufficient to start your air compressor motor.

Verify Capacitor Functionality

If you have both a running capacitor and a start capacitor, check their functionality. Faulty capacitors could be the cause of your compressor not starting. These capacitors can drastically affect the electrical performance of the compressor motor. Ensure both capacitors are working as expected.

Check the Connection

Confusingly, the wiring in your situation is described as 'white and black being hot 110V each, and bare going to ground.' This is not a standard configuration for a 220V air compressor. Typically, a 220V compressor uses red, black, and bare wires. The red and black wires should be connected to the 220V supply, and the bare wire should go to ground.

Identify Your Wiring Issues

Given that your wiring is currently set up with black and white as individual 110V hot wires, you need to reconfigure your wiring to support the 220V supply. To achieve this, you should:

Paint the White Wire

One way to clearly show the white wire as a hot wire is to paint the insulation of the white wire with red nail polish or a red permanent marker. This will help you immediately identify the correct wiring during troubleshooting and repairs. Additionally, you should connect the white wire to the same 220V supply as the black wire.

Ensure that the wire configuration in your circuit breaker is correct for a 220V supply. If you have a breaker or fuse that supports 220V service, both the hot legs of the circuit should be connected to the breaker, and the neutral/ground should be connected to the neutral terminal on the breaker.

Ensure Proper Safety and Circulation

Further, check the oil level and try loosening the motor/compressor combination mechanically. Ensure the release valve works correctly; when the compressor is pressurized and the power is switched off by the regulator, the purge/relief valve should open, dropping the pressure in the filler tube between the compressor and the tank. This helps to prevent high inrush current or the motor from stalling.

Seek Professional Help

Given the complexity of electrical systems and the potential for injury, especially with high-voltage systems like a 220V compressor, consider consulting a qualified repair professional. They can diagnose and correct the issue safely and effectively. Remember, 220V is lethal, and incorrect wiring can result in serious harm or even death.

Stay Safe and Consider a Darwin Award

The compressor is doing its best to communicate the need for proper wiring. Although it can only hum, this is better than the hum that electricity makes when it passes through your body. Be cautious and ensure that you or someone assist you in handling these electrical components. If you continually misuse high-voltage components and put yourself or others at risk, there is a very real possibility you may be eligible for a Darwin award.