Compressor wiring help needed

-
C

Colohusker

Well-Known Member
Joined
Aug 4, 2009
Messages
240
Reaction score
2
Location
Colorado
Okay, picked up a compressor this summer from an auction. It's an 80 gallon dresser with an Ingersoll Rand type 30 pump and a 7 HP motor. Finally have time to get it situated and wired up, but have some questions I'm hoping someone can help me with.

I have a 240 line that I've used for my welder, old compressor, etc. Attached is a picture of the motor control on the compressor. I know the 2 red circles are where 2 of the wires from the 240 circuit go to, and the blue circles are where the wires from the pressure switch go to.

My main question is which 2 wires from the 240 circuit go on L1 and L2,one hot and neutral, or the two hots? And where does the 3rd wire from the 240 circuit go to?

Thanks,
Scott
 

Attachments

Colohusker said:
Okay, picked up a compressor this summer from an auction. It's an 80 gallon dresser with an Ingersoll Rand type 30 pump and a 7 HP motor. Finally have time to get it situated and wired up, but have some questions I'm hoping someone can help me with.

I have a 240 line that I've used for my welder, old compressor, etc. Attached is a picture of the motor control on the compressor. I know the 2 red circles are where 2 of the wires from the 240 circuit go to, and the blue circles are where the wires from the pressure switch go to.

My main question is which 2 wires from the 240 circuit go on L1 and L2,one hot and neutral, or the two hots? And where does the 3rd wire from the 240 circuit go to?

Thanks,
Scott
Click to expand...
I am not an electrician, but I did hookup my 220 volt single phase welder and air compressor, My 220 volt circuit, has 2, 110v lines 1 red and 1 white and 1 ground green, that is how mine is set up. so both wires are hot I dont think there is a neutral with 220, only a ground.
 
240 is 2 times 120 so 3 wires is 2 hots and one ground. More recent codes require a 4th neutral .
 
L-1 and L-2 mean line one and line two which are your two 110volt feeds. You have two "hot" 110volt and one white neutral. You should also have a ground to ground the compressor back to the power panel ground/neutral bar. Your feed cable should have a "red" hot line a "black" hot line a "white" neutral line and a "green" ground line. If you don't have the ground you can add one and ground the compressor motor to an actual ground rod driven at least 5 foot deep in the earth adjacent to the compressor.
 
Your three wire hook up will put the neutral to the ground you have circled all single phase, 220/240 . Your neutral will be your ground and if you had a 4th wire it would be just a second ground for commercial installations, it is like hooking up a hot water heater. This is single phase ??
 
Thanks for the replies, I'll give it a try tonight. Mine is older wiring with 2 hots and a ground without the neutral. So the 2 hots would probably go on L1 and L2 and ground the panel and compressor from what I'm seeing.
 

Yes, it's single phase 240 circuit and I looked up the motor plate last night and it's a 240 single phase motor. My old compressor was a capacitor motor and didn't have the external motor control, so just wanted to double check before I get yelled at by the wife for blowing the main breaker, again. :)

Thanks for all the replies and help!
 
yup your two hot wires should be l1 l2 which is line in those two wires should tie into the breaker and a ground along with them, im a sparky here at newport news shipyard
 
Thanks for the help! One last question, where does the ground wire hook into? Just a lug on the case, or somewhere else?
 
should be a green screw if not the case just makesure to take a lil paint off were you put it to make a good ground even add a lil anti-seize were the paint was gona to prevent rust
 
You must log in or register to reply here.
-
Back
Top Bottom