Air compressor wiring. . . Help!




Zoinks!

Registered
I just bought a kobalt 60 gallon air compressor, and didn't realize till I got it home that it didn't come with a plug already wired to it. . . I looked in the owners manual to try to find out what I needed, but all the manual says in regards to wiring is "get professional electrition to install wiring. . ." It doesn't look that difficult. There are 3 terminals open to use, but I just don't know which ones to use. . . I'll post some pictures of the terminal board if someone can help me it would be much appreciated. Oh, and it's a 220 hookup, not 110. It says voltage spread 208-240, so I'm assuming that means 220 is ok?

In the pic the black arrow is pointing to chasis ground, the red is pointing to one of the open lugs, the white wire from the on/off switch is attached to one of the lugs on this group, and the blue wire is pointing to the other 2 open lugs. I'm not sure what these are for, but I'm assuming they're for the pressure switch. The manual says, "on models not supplied with a power cord, the electrical power must be wired into the pressure switch by a licensed electrician."

Compressor 005 2.jpg
 

stlbusarider

Donating Member
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It looks like the same one I have. You need to hook the wiring up to the switch in front not to the motor. It's the same as 110 White is common, black is power, green is ground. Pull the plastic cover off and you should be able to figure it out easily, as long as its a single phase compressor.:beerchug:
 

Zoinks!

Registered
It looks like the same one I have. You need to hook the wiring up to the switch in front not to the motor. It's the same as 110 White is common, black is power, green is ground. Pull the plastic cover off and you should be able to figure it out easily, as long as its a single phase compressor.:beerchug:
Thanks for the help! I was lookin in the wrong spot! Pulled the cover off the switch and found a diagram, 2 lugs, and 2 ground points. Do I need to use both ground points or is 1 ok? Also, I have a pic of the outlet. From what I've seen in lowes this outlet is ok for 125 or 250 volts. How do I know which I have? I think it's a 220 outlet, but I'm not sure. Which recepticals should I put the meter leads in to check the circuit votage? Also, it says "3 wire, non grounding" in the description of the outlet on lowes website. Shouldn't it have a ground? Sorry for the probably stupid questions, but I'm a COMPLETE novice to household electrical. Ask me about DC and I can answer your question, but when it comes to AC I am not your man. Lol.
 

Pardini

Donating Member
Registered
On a 240 vac outlet the two terminals on the top in the pic are L1 and L2, black and red wires usually. The bottom is neutral- white wire. There is no seperate ground- green wire in that circut. Neutral runs back to ground at the service panel.

Properly wired your meter will read 220 to 240 between the two top terminals, and will read 110 to 120 between either top terminal to the bottom. So red to black 240, black to white 120 and red to white 120.

That motor should be pre wired 240, by moving the terminal wiring it can be converted to run on 120.

That outlet you have pictured is 30 amp rated and should be wired with #10 wire 10/3 no ground to the backside. Size your power cord by amp draw of the motor. If the motor only draws 20 amps max then you can size the powercord to #12 wire.

You could fuse a 20 amp compressor with a 20 or 30 amp breaker as long as you use #10 wire from the outlet back to the breaker. Just don't over fuse the wiring, ie. 30 amp breaker with #12 wire.

30 amp circut / # 10 wire
20 amp circut / #12 wire
15 amp circut / #14 wire

Going bigger on wire size is ok, just a waste of money, but don't go smaller than listed.
 

Zoinks!

Registered
On a 240 vac outlet the two terminals on the top in the pic are L1 and L2, black and red wires usually. The bottom is neutral- white wire. There is no seperate ground- green wire in that circut. Neutral runs back to ground at the service panel.

Properly wired your meter will read 220 to 240 between the two top terminals, and will read 110 to 120 between either top terminal to the bottom. So red to black 240, black to white 120 and red to white 120.

That motor should be pre wired 240, by moving the terminal wiring it can be converted to run on 120.

That outlet you have pictured is 30 amp rated and should be wired with #10 wire 10/3 no ground to the backside. Size your power cord by amp draw of the motor. If the motor only draws 20 amps max then you can size the powercord to #12 wire.

You could fuse a 20 amp compressor with a 20 or 30 amp breaker as long as you use #10 wire from the outlet back to the breaker. Just don't over fuse the wiring, ie. 30 amp breaker with #12 wire.

30 amp circut / # 10 wire
20 amp circut / #12 wire
15 amp circut / #14 wire

Going bigger on wire size is ok, just a waste of money, but don't go smaller than listed.
Gotcha! Thanks for the help, I really appreciate it. Now I just have one more question. I was gonna just go buy a dryer power cord and use that, but the only ones I could find were 125V. It was 30A, 10/3 wire Will that work? It said on the package 125/250, but on the tag on the cord itself it said 30A 125v, and it didn't say which ones were power and which was neutral. There were all the same color and had ring terminals on the end of the wires. After that I was just gonna get a plug and some wire and make it myself, but I couldn't find the male end connector for the outlet pictured above. I'm really starting to get agrivated with the whole thing and am about to hire an electrition to just come do it for me, but I'd really rather save the money. The manual says to use this type of outlet
 

Pardini

Donating Member
Registered
The first pic is a standard 30 A outlet for an electric dryer. That dryer cord is fine, but they only come in 6' length max. They are cheap. There are male 30A plugs that you can wire your own 10/3 wire to. The plug alone is probaly 3x the cost of the dryer cord, plus the wire. Generally, the dryer cord will have left to right L1-N-L2. If in doubt check it with the ohm meter. The L shaped terminal should be connected to the center wire of a flat moulded cord. The other two are interchangable.

The second outlet will work too. The pin configuration makes no difference as long as its rated for your voltage and load.

That compressor should have a dedicated circut. Meaning that the breaker it's connected to should not feed anything else. You'll have to add a 240V breaker to your panel. You need to have an open space, really two with full sized breakers. If not you may need to use duplex breakers on some of the other circuts in the panel to make room. A 240V breaker needs to connect to both buss bars in the panel. You can't get 240V's by feeding L1 and L2 off the same buss bar in the panel.

The other thing to consider is the length of the wire run from the panel to the compressor. If it's excessive you will need to bump the wire size up to compensate for the voltage drop.

Couple of other things, not a good idea to run exposed romex cable. Exposed runs should be in conduit. Don't run romex inside conduit, use single wires. Romex in conduit would be ok up to 3' max.
 

Zoinks!

Registered
Is neutral the same as ground? Do I run the neutral to the ground screw? There are 3 terminals on the switch. L1, L2, and there are 2 ground screws. There is a white wire wire that runs from T1 to the motor and a black wire that runs from T2 to the motor. L1 and L2 are available to connect to and there are 2 ground screws that don't have anything connected to them. If I'm understanding correctly, I would run L1 and L2 to their respective terminals and then run the neutral lead to one of the open ground screws on the switch. Correct?
 



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