compressor question

[Ware91711]

So I'm fairly new to air compressors, used them a lot but never owned one of my own until now, and I have a quick question.

It's a 120v 20 gallon compressor that I acquired for free. Works great and holds pressure so it's good to go to work. My question is this, can I plug this into a switched outlet to turn it on and off? I would think it would be ok, but I don't want to burn anything up switching it on and off from a receptacle rather it's own off/auto switch.

Thoughts or opinions?

 

[finn]

I think most wall switches are rated at 15 amps.

What is the run and start load on the motor data plate?

I'll look into a dedicated motor switch designed to disconnect shop equipment, not a light switch.

 

[Ware91711]

That was one of my concerns. I'm not positive on those specs, most all of the info was wiped off over the years, the guys dad wiped it down with acetone of all things :/

The reason I ask is I am building a workbench and want to place underneath for space reasons. Thanks for the help! Electrical has never been a strong suit for me

 

[sam.coll]

Im not sure about the compressors in the states but here if you turn it off or unplug it while it is running (i.e the motor is turning and building pressure) the unloader valve wont operate to clear the pressure between piston and check valve so when it starts up again it will have to start under load which isnt good for the motor and might trip a breaker from in rush current. Hope that makes sense.

 

[sam.coll]

If you wait for the compressor to build up and cut out automatically and then switch it off at the wall/switch I cant see there being any problem.

 

[Ware91711]

Yeah I definitely wouldn't stop or start under a load, that's not good on any electric motor. My main concern is I don't want to overload my house circuit or a switch to small. I'll look at my compressor motor to see if that info is on it.

I wouldn't mind having to wire up a box to put on my bench to turn it on and off if that's what it takes for a switch rated high enough. I'll post back with the start/run amps if/when I find it. It's an old compressor from the early 90's, all it cost me was an 18 pack of miller lite cause I didn't feel right taking it for free

 

[Ware91711]

So I just checked the motor, all it says is 110/220v and 15/7.5a. So I should be fine to have that on a normal 20a circuit, nothing else is on it but a battery charger for drills, and use a normal 15a switch right?

 

[sam.coll]

Yeah I definitely wouldn't stop or start under a load, that's not good on any electric motor. My main concern is I don't want to overload my house circuit or a switch to small. I'll look at my compressor motor to see if that info is on it.

I wouldn't mind having to wire up a box to put on my bench to turn it on and off if that's what it takes for a switch rated high enough. I'll post back with the start/run amps if/when I find it. It's an old compressor from the early 90's, all it cost me was an 18 pack of miller lite cause I didn't feel right taking it for free

Ok that makes sense, I cant see there being a problem overloading the house circuit as the load is always going to be the same regardless of where it is switched on, as long as the circuit is of sufficient capacity to begin with. I have my compressor at home in NZ wired to a 20A socket in the shed where the compressor is and a 20A isolation switch at the front door to the garage, when I leave the garage I listen to hear the compressor is not running and turn the isolator to de-energize it. I also have above the door a 25W light bulb connected to the same circuit to remind me at night to turn the compressor off.

 

[firebox40dash5]

Only issue I could see is if you run the pressure down with it off then switch it on with the pressure switch on, it'll be trying to start right off. Not sure whether the startup current combined with the FLA being the same as the switch rating would be an issue.

I'd be cruising CL looking for a cheap old contactor from a 3 phase starter. But I really like overkill.

 

[Ware91711]

Only issue I could see is if you run the pressure down with it off then switch it on with the pressure switch on, it'll be trying to start right off. Not sure whether the startup current combined with the FLA being the same as the switch rating would be an issue.

I'd be cruising CL looking for a cheap old contactor from a 3 phase starter. But I really like overkill.

Not sure if I follow you here. If I run it down when it's off, even without a switch, it will want to start right up correct? Also, what is FLA?

 

[firebox40dash5]

Not sure if I follow you here. If I run it down when it's off, even without a switch, it will want to start right up correct? Also, what is FLA?

I'm saying if it drops below cut-in with your switch off, and you're leaving the switch on the pressure switch on, the motor is gonna be starting as soon as those contacts close. I wouldn't doubt that the switch could handle running it with the contacts closed until the cows come home, but regularly applying the rated load as you switch it might not work so great. Although I'm pretty sure you can get a 20A switch, too.

FLA = full load amps, which AFAIK is usually the nameplate amps. You might poke around online and see if there's a spec for max inductive amps or motor starting amps for a typical switch, too.

 

[bczygan]

FLA is Full Load Amps.

 

[Ware91711]

I'm saying if it drops below cut-in with your switch off, and you're leaving the switch on the pressure switch on, the motor is gonna be starting as soon as those contacts close. I wouldn't doubt that the switch could handle running it with the contacts closed until the cows come home, but regularly applying the rated load as you switch it might not work so great. Although I'm pretty sure you can get a 20A switch, too.

FLA = full load amps, which AFAIK is usually the nameplate amps. You might poke around online and see if there's a spec for max inductive amps or motor starting amps for a typical switch, too.

Ok, that makes more sense. Thanks! I'll look into a 20A switch then. With such a small garage, about 20x20, I have to make every inch count to still park our cars in it. The wife's Patriot fits perfectly with room enough to spare for my tool box and such, my Charger is a whole other story haha. I can barely fit a 18" deep shelf in front of it. If I put the compressor under the work bench then it makes it hard to get to the switch mounted on it.

Thanks for all the info. I've crept this forum long enough, it's time to get cracking on the garage.

 

[sam.coll]

Yeah sorry I wasn't recommending you get a 20A switch I was just explaining what I had but I believe the voltages used in America are different to what we run here in New Zealand.

 

[Ware91711]

Yeah sorry I wasn't recommending you get a 20A switch I was just explaining what I had but I believe the voltages used in America are different to what we run here in New Zealand.

Oh ok, I think I'm considering building a switch to mount to my workbench. My neighbor is actually a certified electrician. Amazing the things you find out when you talk to neighbors haha!

Anyone have success mounting a moisture trap to a wall? Here's how mine is setup for now