Any electricians out there? semi-complicated questions

I need advice from an experienced electrician. I got a new/ used compressor for the shop, but it uses some kind of seperate box to start the motor, and I have no idea how to wire it. If anyone knows anything about these things, please PM me, I appreciate the help, and sorry for the O/T....

 

thats about as clear as mud. sounds like the box you are talking about is either the pressure switch or the starting capacitor. the capacitor is almost always housed with the motor, so i'd bet you are dealing with the pressure switch. i assume this is a 220volt air compressor, that is intended to be wired directly into the power. take a picture of what you are looking at and i'll tell you whats going on. dave

 

could be 3 phase, that has a seprate power tp start it and another to run it,

 

Its not the pressure switch, and yes it is 220, it has to be hard wired through this box. I'll take a picture and send it to you tomorrow, 413...Thanks.

 

if it hard wired yo should just have 3 wires comming out of it ? green white black ?2 power wires and a ground

 

It's probably a starter, which is like a heavy duty relay. Your pressure switch contacts can melt together (from arcing, usually when the contacts open up) so the pressure switch brings in the relay (starter) and the starter in turn closes it's heavy duty contacts to start the motor. Just bring your 220 to the top of the contacts and the motor leads to the bottom. One side of the line (110) will go to the pressure switch and from there it will go to the coil of the starter. Clear? I can post a simple diagram if you need it. If the pressure switch contact weld themselves closed and your pressure relief valve also failed you can have a pretty good bomb sitting there in your garage

 

Ragtop, if you wouldn't mind, a diagram would probably help a lot.....

 

My guess is a starting contactor,which are abel to handel the current. Line voltage on the top,Load on the bottom,the contactor is controled by a coil,it can be any voltage 24 to 480 volts,coil is in the center of the contator with the voltage on it.Coil can be controled by the pressure switch and a start/stop switch. The pressure switch is in series with the coil.The NEC says that you must be abel to disconect the equipment,by unpluging ,a disconect or in site of the breaker.Hope this helped, GOOD LUCK PATINA

 

Here ya go:

 

Here's the box, getting power to it is no problem, theres a light switch mounted to the side of it, so getting power in is pretty self explainatory. there are 2 wires coming out of the terminals toward the top, where the yellow terminals are. Where do they go?

 

And heres the compressor side of it. I think I understand the pressure switch part of it, I'm fairly sure the pressure switch is wired between the box and the compressor. there are two leads out of the compressor.

 

I don't get it - what does the light switch have to do with it? The compressor is 220 volts right? The two leads at the top are where the power comes in. The two screws at the bottom are where you connect the two motor leads

 

Not quite that simple. Yes the compressor is 220, but the motor requires a "starter" that's where the box comes in. The light switch is just something someone added to be able to turn off power to the whole setup, I assume.

 

Flyin' Eye
I just noticed that you are in Forest Grove. I went to FG High.
Someone said its a junior high (middle school) now.
I used to live out on 26th catty corner from Dorman's Speed Shop.
I'm not a pro electrician so I won't even try to give you wireing instructions. Sorry I can't help.
The PknBner
OH, look on the tag on the motor and make sure its not 3 phase. Duh, that's what I started out to say.

 

What horsepower/watts is your compressor?if it`s a bit on the beefy side you need to use a contactor. this is simply a large switch that is operated by a control circuit i,e, your pressure switch and you "light switch". the cicuit feeds through your switches and then to your contactor coil(usually marked A1)A2 goes to neutral.The mains is fed into the top of the contactor in either single(220 volt or three phase 415 volts) and out of the bottom of the contactor to the compressor/motor, whatever.If you are unsure of any wiring get a pro to check it out.the most important wire is the earth?ground wire, do not leave this unconnected.