240 volt air compressor wiring advice from Campbell Housfeld skewed???

[James Blais]

Hi. I need some help w/ this. I just bought a Campbell housfeld stationary upright air compressor w/ a 240 volt, capacitor start 15 amp motor. The unit came unwired. The owners manual shows a wiring diagram w/ two sides of the pressure switch; one side shows two terminals wired to the motor; if you lift the pressure switch cover you will see a black wire and a white wire running from these terminals to the motor. The other side of the pressure switch from those teminals (the two empty ones to which wiring connects from the users sub panel) -the wiring diagram indicates that there is a 120 volt line which attatches to each of these empty terminals. (240 volts total). As one of the wires going to the motor is white, I emailed campbel Housfelds tech line and asked them if they had mistakenly wired the motor for 120 volt instead of 240 volt? I also asked them if this unit utilizes a "neutral" wire in addition to two hot wires and the ground (ground being shown in diagram in manual, but no neutral connection shown). There reply was, Quote:

"Our Solution :

The answer to your issue is that the white and black wire coming from your motor is your 2 hot wires. The white wire and your neutral wire coming from your service panel will be put under the green screw on the base of the pressure switch".

Thank You Thank you for using our system.

Question: Is this a correct solution? I thought that linking a neutral wire as the ground or to the ground was an "old school" outdated and unsafe practice. Should this unit just run two hot leads to the pressure switch and a ground, as shown in the wiring diagram in the manual? Shouldnt the two hot leads running to the motor be colored black and red, and not black and white? (white indicating a neutral, and not "hot" connection). Is a neutral necessary for the circuit to function? If so, I would not think that the techies at Campbell Housfeld would be telling me to link a neutral wire to the ground wire at the compressor. But wouldnt' this be unsafe? (linking neutral and ground at the compressor?). Any help on this would be greatly appreciated, thanx, J.B.

[Bob Vaughan]

It is.

Make sure the motor nameplate rating is in fact 240 volts, and wire it according to the wiring diagram. Ignore the fact that they used a white wire inside the motor.

I suspect that the motor can be strapped internally for 120 or 240 volts, and that is why one of the wires is white. In this case, if the motor is wired for 240, the white becomes a hot.

Connect the two hot wires, and the ground, and leave the neutral disconnected. For the wire from your subpanel, use black and red.

[RBM]

It sounds like you're over complicating this. Forget about wire colors as usually a two wire cord or cable uses a black and a white. You need three wires from your power supply: two hots (240) which go on the pressure switch and a ground, which goes on the ground terminal. Just be sure that they are large enough to carry the amperage of the compressor

[James Blais]

thank you! James

-- James Blai

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