Help with new Compressor wiring

[rpsurfr]

I bought a used Quincy Air Compressor with a 220 steping down to a 110 I think. My old unit had a 20 amp fuse- can anyone tell me how to size the unit for the main line?
I fear I have only 3 wires and will need a 4th that will be not only a pain but expensive.
Any help and ideas would be wonderful
Ron

 

[GeorgiaHybrid]

Why do you think it steps down to 110 from 220? Can you post pictures of the motor plate? Does it have a mag starter? If yes, pictures there also. Include a photo of the pressure switch also.

Either way if it is 220, all you need are 3 wires. The pressure switch side might run a 110 leg thru the mag starter but I can't see the need for a neutral and a ground to be able to run 110.

 

[mmg440]

Maybe even a 3 phase. That you would need more then just a wire. I am sure there are memeber that can help sizing but first it will have to be idenified for what it is. This doesn't make sence to me "...220 steping down to a 110..." Don't really know what you are tring to say with that.

 

[Dragster Racer]

So is 10-2 with ground ok for most compressor installs? Or do you need 10-3 for some reason for just single phase?

 

[Gary S]

So is 10-2 with ground ok for most compressor installs? Or do you need 10-3 for some reason for just single phase?

We can't recommend a wire size until we know the load. What size compressor motor are you trying to insall?

 

[GeorgiaHybrid]

So is 10-2 with ground ok for most compressor installs? Or do you need 10-3 for some reason for just single phase?

For most home compressors, that would work. For higher HP motors or long runs of wire, you might need to go up a size to 8 GA wire.

10-2 with ground is all you need for a 220 circuit. If you are running to a sub-panel or if you plan on adding a 110 accessory to the compressor (110 volt hour meter for example) the extra wire will be required and you will need 10-3 with ground or separate wires in conduit.

 

[Dragster Racer]

We can't recommend a wire size until we know the load. What size compressor motor are you trying to insall?

I understand that. I was more curious about the number of wires. I ran 4 for a dryer circuit, but I understand that some dryers run 110V controls, thus the need for the fourth wire. I ran 10-2 yesterday for the future compressor, which won't need more than 30 amp circuit, and I wanted to make sure I did the right thing.
Thanks for the responses.

 

[rpsurfr]

Thanks guys. I will get the information and post it again with pictures and more detail now that I know what to look for

 

[Falcon67]

For my 3 1/2HP unit I used regular 12-2/wG. For a 220 Motor, you only need two wires and a safety ground. As noted, wire size depends on load and run length.