I have a 220v cord with 3 wires on a compressor and a plug and receptical with 4 hook ups. How should I hook up the 3 into the 4 correctly to achieve the 220 volts I need. The plug in question is a NEMA L14-30 if that helps. I hooked it up already but I think im only getting 110v out of it with: green as ground, white as neutral and black as hot with one hot slot left over.

Chris

 

sounds like you need to get a new 4prong male plug

 

You're only getting 110v because you've only got one hot.

I'm assuming you have a L14-30 plug and an L14-30 receptacle and that they fit together just fine? For 208 volts, you don't need a neutral, but you need two hots. The cord on the compressor only has a black, white and green wires and you're sure it needs 208v? If so, make the plug up with the white as a second hot wire. It sounds to me like you don't need the L14-30, but an L6-30 plug and receptacle. That would only require 2 hots and a ground and no confusion.

 

So I could use the white as my second hot then? I thought it was possible but wasnt sure. As for the plug and receptical, they have to stay because its part of a generator. The generator came with a L14-30 female receptical which is a 4 wire set up.

Thanks for the input

 

The fact that the compressor cord has only a black, white, and green wire makes me wonder. The white wire should always indicate a neutral. Make sure you need 208v for the compressor.

Okay, I just looked up the L14-30. Looks like you've got 2 phases and a neutral, meaning it can produce either 120v or 208v. You might need a power strip with an L14-30 input plug and it should have both 120v and 208v outlets. That way you can use the correct L6-30 or L5-30 or whatever you need. I don't think you should use a 4-wire plug on a device with only 3 wires. Just my $.02. Again, I'm no expert. There are guys on here who are electrical engineers or stuff like that, if you want to wait for a second opinion, hich I would advise.