Wiring up new 240v compressor...
 

So I finally got a buddy over with a big pickup and bought a new 60 gallon compressor at Lowe's the other day. Putting the plumbing was a non-event, but the electrical is stumping me...

My wall outlet is a 14-30R, which is a 4 prong plug with green, white, red, and black wires as seen on the 30A wall plug I bought for the compressor.

But the compressor only has two posts to connect, white and black - green is a no brainer chassis ground. Question is where do I put the red wire, which is apparently a "hot" wire and is carrying 120v like the black? Intuition tells me to stack the red and black on the black colored terminal, but I'm not one to guess and kill new equipment.

Any experts out there care to lend me some advice?

do not stack the red to black. a 220v line gets it by 2 individual 110 sources. the red and black lines each should have their own individual breaker. give me a few min and ill repost how to do it. i wired up my 220v compressor myself from adding the double breaker all the way to outlet then to compressor.

edit. red goes to white, black to black. in typical 3 prong setups neutral and ground are combined. on the "L" terminal i think.

I get home around 9:30. ill look at my compressor and also post pics. please don't wire anything until then lol unless an electrician chimes in.

Get a hold of Phil <<86TA>>.

He can help you out with exactly what you need.

Phil fell off the earth

We have seen Phil more recently than we have seen you

bah. i was around for lunch on friday :mrgreen:

On a 220v line, the red and black are both 110 sources. With my wiring, I chose a wire that was just black/white/ground (12/2 or 10/2 I think). I also used a 30A 3 prong plug.
There is no neutral wiring needed in a 220v compressor circuit,(other appliances may require it because part of them do utilize just one of the 110v lines for a typical 110v circuit)
The ground wire is like normal and goes from the ground screw on the compressor to the ground strip in the service panel.

So in your case, red and black would go to the compressor white and black. Ground from plug goes to ground on compressor, and the neutral in the outlet is not needed so no connection is required on the 4th prong on the plug.


If you are still confused, Here are pictures of mine...



Outlet and plug

http://i32.photobucket.com/albums/d5...ps06b413c0.jpg


Compressor connection (and yes, I know I need to change the wire clamp on the compressor, lol)

http://i32.photobucket.com/albums/d5...psca82f200.jpg

Outlet wiring (in this case, black and white are interchangeable)

http://i32.photobucket.com/albums/d5...ps99759591.jpg

plug wiring (once again, black/white interchangeable, as you can tell the plug/outlet have them switched)

http://i32.photobucket.com/albums/d5...ps6f5f0761.jpg

Double breaker (same black and white that run to the outlet. Also notice 30A breaker to match the outlet and that the wires are the thickest in the whole box)

http://i32.photobucket.com/albums/d5...ps8f9ca470.jpg

Black sheathed wiring in top right corner is the compressor line (notice only black/white/bare)

http://i32.photobucket.com/albums/d5...ps1c3b7d43.jpg

Thicker bare wire up top is the compressor ground (5th terminal down)

http://i32.photobucket.com/albums/d5...ps5a9e22e6.jpg

overall view of the service panel

http://i32.photobucket.com/albums/d5...ps4cff77eb.jpg

Now that makes sense!

My breaker box looks the same as yours - previous tenants ran 2 red wires to the plug in question, but that is just a formality as the outlet is wired correctly as I already tested it.

So I leave the white wire off and connect red, green, and black... Easy.

If you need any further help I can confirm that Phil is around....he bailed me out with some electrical help in my shop last week.

Replied to your PM paul.

But for the sake of it, the L1430 receptacle is 30amp 120/240 volt. Meaning it has 240v across the 2 colored wires, or x and y on the back of the cap, and has a neutral and ground on the w and g ternimals. You will have 120v from either of the 2 colored wires to the white/neutral wire.

You don't need the neutral for your application, you should change the plug on the wall to the proper configuration, which I think is L6-30, which should be 30amp 240 volt. You could just leave it alone, buy the matching L14-30P male cord cap and just not use the white terminal, its not dangerous, just not 'correct'.

I haven't fallen off anything, just been really busy
-Phil

hey Phil, what do you know about baseball field lighting? :)

If you build it, they will come?

I don't think Phil has any experience with lighting :kneeslap:

We got bulbs out and we need to find someone to change them :)

oh, and some need to be realigned.

Phil,

Thanks for the reply and PM.

You need a bucket truck?

Yes. And it appears a very tall one. the town does not appear to have one that goes high enough, sometimes they do stuff like that for us since they give us nearly no money I guess they feel bad.

Plus it seems there is a special way to aim these things with some kind of meter that measures lumens. I guess at least one of the poles has twisted a bit with age.

Oh, wooden utility poles?

Pats brother has a bucket truck, he does tree service.

yeah on the back field.

Poles on the back field? :nick:

I know a pretty good lighting guy. He's all about lumens and CRI.

Thanks to all on the wiring advice - works as it should...