wiring new comressor 220v White-Green-Black?

^^^^^^^^^^^^^^^^ That's what I would do, although I am sure there are some here who will that it is not 110% safe, since the fourth wire is missing. So to satisfy the ultimate in safety, you could run a wire from the frame of the compressor to ground (not neutral).

"Leo Lichtman" wrote:

The described connection is not even 100% safe, but that's not due to the number of wires, it's due to connecting the ground wire to the wrong connector, and leaving the wrong pin not connected to a wire.

There's no need for a 4th wire if the device is pure 220 - but the green should be connected to ground, and the neutral should be left not connected, as the compressor (pure 220V, not 110) does not need it. Hot-Hot-Ground is just fine. The reason you don't have a whip with Black-Red-Green has to do with common wire manufacturing for

You do not want to connect the safety ground of the compressor to the neutral wire - ground and neutral only connect at the main service entrance, and everywhere else they should be separate, and remain separate, and not be swapped willy-nilly.

Are you sure the compressor is wired to operate on 220v??

Green is almost always ground on US made appliances and it should connect to the odd shaped prong. But make sure you don't have a 120v compressor. Many of them can be optioned for either 120v or 220v. If this is the case, there should be a wiring diagram on the name plate showing how to option the machine for either voltage.

Industry standard for the green wire is frame ground (or 'bond' wire) Your compressor appears to be wired for 220vac only and does not need the neutral connection. Connect the black and white in the whip to the hot-hot in the supply (usually black and red) and the green to the ground (usually green) in the supply.

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Standard 3-wire cordage in the USA is all black-white-green. Open up the motor & pressure switch and look to make sure, but the safety ground should always be on the green, making the 220V hot conductors in the cord the black and white wires.

If the compressor is a straight 220V motor load only, you do not need a neutral connection, do not connect anything to the neutral pin in the dryer plug.

I suppose the compressor maker could special order a batch of cord marked black-red-green, but that would be an extra expense they don't want to spend when the competition doesn't have to. Unless they amend the electrical code to require it, you won't see it.

That's why they invented red colored electrical tape and red colored shrink tubing, so you can make your own reminders. ;-0

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When I worked in project supervision, our design electrical engineers used to specify all kinds of nicely colour coded wiring then almost demand compliance. It's easy to get the manufacturers to run a couple miles of wire in each of seven special, whimsical codes, YEAH RIGHT! Gerry :-)} London, Canada