Switch on 220 compressor

[Need more space]

Thinking of ways to wire my new compressor, its a 220 sailor-beall with a 5 hp motor. My main question is what are your thoughts on wiring a switch to override power to compressor to avoid running due to pressure loss in the event of a leak. I thought I could keep it simple and find a breaker that's rated as a switch, or maybe wire a simple switch in between. However I'm concerned a switch won't last long running such a load and switching it daily.

 

[teamextreme]

Either approach works. They make hp rated switches that will work fine for a disconnect, that's what I used. The only way it would be hard on the switch is if you're switching it under load, which you shouldn't be doing, not only to avoid abusing the switch, but I'm pretty sure the unloader feature on the pressure switch doesn't do it's thing when you kill power under load. This is what I used, a Leviton MS302-DS.
https://www.leviton.com/en/products/ms302-ds

 

[wyliesdiesels]

It sounds like OP wants to disconnect comp while running if it develops a leak.

Does this comp have a mag starter?

How is it wired to the electrical panel?

 

[Need more space]

It sounds like OP wants to disconnect comp while running if it develops a leak.

Does this comp have a mag starter?

How is it wired to the electrical panel?

Not really concerned about turning it off when running but more so like the idea of flipping power of at night to keep it from running when not needed.

Yes it has a mag starter, and not currently wired. Just got it yesterday

 

[TRWham]

Add a switch (can be a light switch in a separate box) to your control circuit to break the current from the pressure switch to the contactor coil. Alternately, if the circuit breaker is switch duty rated (not likely at that amperage as I think about it), you can just kill the power at the panel.

 

[alfredeneuman]

Add a switch (can be a light switch in a separate box)

The rules for a switch wired separate from the starter enclosure are different from 1 in the same enclosure.

If the circuit is 45 amps or less, use can use #14.
If the circuit is > 45 amps, then #12
If the switch is within the enclosure, you can just use the wire size (#18) that the existing control wire is.

It will need to be a maintained contact switch, but not necessarily a light switch, rated for the 240 volt system.

https://www.homedepot.com/p/Gardner...h-Button-Switch-Black-1-Pack-GSW-21/100147727

 

[alfredeneuman]

The switch should be wired to control the starter's coil, that way it doesn't switch the whole load.
Just disconnect either wire of the coil, and run it through the switch.

 

[TRWham]

The rules for a switch wired separate from the starter enclosure are different from 1 in the same enclosure.

If the circuit is 45 amps or less, use can use #14.
If the circuit is > 45 amps, then #12
If the switch is within the enclosure, you can just use the wire size (#18) that the existing control wire is.

It will need to be a maintained contact switch, but not necessarily a light switch, rated for the 240 volt system.

https://www.homedepot.com/p/Gardner...h-Button-Switch-Black-1-Pack-GSW-21/100147727

Sorry, I did not mean to imply just any light switch would do, but there are 240V switches readily available at home centers that will do the job.

https://www.homedepot.com/p/Leviton-30-Amp-Industrial-Double-Pole-Switch-White-R62-03032-2WS/100356941?MERCH=REC-_-rv_search_plp_rr-_-NA-_-100356941-_-N

 

[LX-Markham]

This is what I used, a Leviton MS302-DS.
https://www.leviton.com/en/products/ms302-ds

Have the same switch controlling the receptacle for my compressor.

 

[alfredeneuman]

If you read the spec sheet that switch is rated at 2hp @120/240V and takes the full load
The OP's compressor is a 5HP.

 

[teamextreme]

The spec sheet in that link lists 5HP @ 240vac. Where did you see 2HP? Either way, sounds like OP has a starter, so a simple 15A toggle switch will work fine to disconnect the control circuit. Regarding the statements that a switch needs to be rated for 240V, why would that be? It's only switching a 120V control circuit.

 

[Norcal]

The spec sheet in that link lists 5HP @ 240vac. Where did you see 2HP? Either way, sounds like OP has a starter, so a simple 15A toggle switch will work fine to disconnect the control circuit. Regarding the statements that a switch needs to be rated for 240V, why would that be? It's only switching a 120V control circuit.

The coil is usually 240V.

 

[TRWham]

The spec sheet in that link lists 5HP @ 240vac. Where did you see 2HP? Either way, sounds like OP has a starter, so a simple 15A toggle switch will work fine to disconnect the control circuit. Regarding the statements that a switch needs to be rated for 240V, why would that be? It's only switching a 120V control circuit.

I was suggesting the switch be used in the control circuit which is usually 240V on a single phase compressor.

 

[TRWham]

If you read the spec sheet that switch is rated at 2hp @120/240V and takes the full load
The OP's compressor is a 5HP.

So do we agree a 2 hp rated switch can handle the control circuit current, then?

 

[7635tools]

I was suggesting the switch be used in the control circuit which is usually 240V on a single phase compressor.

But your only switching one leg of the 240v which is 120v.


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[TRWham]

But your only switching one leg of the 240v which is 120v.


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No, it’s 240V. It is one phase to the other through the coil. There is no neutral even run to most compressor installations.

 

[rlitman]

...However I'm concerned a switch won't last long running such a load and switching it daily.

If the switch is rated for the horsepower rating of the motor, then it won't be worn out switching the load. However, remember that so long as the compressor isn't running, the switch isn't even actually switching the load, so unless you shut it mid-cycle all the time, it won't see any wear and tear at all.

So, if you want to switch the whole load, you can get yourself one of these:
https://www.homedepot.com/p/GE-60-Amp-240-Volt-Non-Fuse-Indoor-Safety-Switch-TGN3322/100676700

If you're hard wiring the compressor, you may want a disconnect anyway, so this is just adding a switch handle to that.

Or, of course, there's the option of just switching the control circuit, but that only helps if you're using a start contactor. Many 5HP compressors run the full motor current through the pressuretrol.

 

[wyliesdiesels]

Have the same switch controlling the receptacle for my compressor.

Whats the HP rating on your compressor?

 

[alfredeneuman]

Where did you see 2HP?

I must have copied the info wrong. Sorry

Anyway it's extreme overkill for use on a control circuit that's going to draw less than 1 amp.

 

[Lelandwelds]

Many 5HP compressors run the full motor current through the pressuretrol.

How long does that last? Whether you call it a mag starter, relay, or a contactor, that's a pretty hefty load to switch directly.


Or is it just overkill and a less than best use of limited dollars?

 

[teamextreme]

I must have copied the info wrong. Sorry

Anyway it's extreme overkill for use on a control circuit that's going to draw less than 1 amp.

Yes, for a control circuit, I was suggesting it to switch line voltage before we learned he had a mag starter.

Interesting, most of the single phase control starters I deal with use 120vac coil, not 240vac.

 

[rlitman]

How long does that last? Whether you call it a mag starter, relay, or a contactor, that's a pretty hefty load to switch directly.





Or is it just overkill and a less than best use of limited dollars?

I don’t know, but switching 5hp through the pressure switch is pretty common, even amongst the top brands. Mag starters are optional.

I happen to have a 7.5hp, where a mag starter is not optional.

 

[7635tools]

No, it’s 240V. It is one phase to the other through the coil. There is no neutral even run to most compressor installations.

Commercial grade 20a switches are usually 120/277v rated so I don’t see a problem using a toggle switch on the control side.


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[Lamakocklee]

How about something like a safety switch wired in before the compressor? Something like this.. Would be wired from breaker to switch to compressor..

https://www.homedepot.com/p/Siemens...-Non-Fusible-Safety-Switch-LNF222RU/202315410

Serves as a disconnect means and is HP rated to 10 hp.

Not sure how long something like this would last if switched on an off everyday though...

Just a thought.

 

[wyliesdiesels]

How long does that last? Whether you call it a mag starter, relay, or a contactor, that's a pretty hefty load to switch directly.


Or is it just overkill and a less than best use of limited dollars?

Motor starters are sized by HP so the load is not too hefty for the starter.

Yes, for a control circuit, I was suggesting it to switch line voltage before we learned he had a mag starter.

Interesting, most of the single phase control starters I deal with use 120vac coil, not 240vac.

So you run a neutral with your phase conductors just so you can use a 120v coil?

 

[BillK]

Ok,

I know I will get flamed for this but . . . . at my business I turn the compressor off every night by flipping the breaker. Its a 7 1/2 hp 3 phase compressor. I have been doing that for 30 years and have never had to replace a breaker.

My small 2 1/2 hp compressor at home is on a dedicated outlet and I do the same thing there. I probably only use the compressor a few hours a month, if that. That breaker has been there almost 25 years.

 

[rlitman]

Ok,



I know I will get flamed for this but . . . . at my business I turn the compressor off every night by flipping the breaker. Its a 7 1/2 hp 3 phase compressor. I have been doing that for 30 years and have never had to replace a breaker.



My small 2 1/2 hp compressor at home is on a dedicated outlet and I do the same thing there. I probably only use the compressor a few hours a month, if that. That breaker has been there almost 25 years.

No flames here. The breaker won’t see any arcing unless you shut it while the compressor is pumping.

 

[TRWham]

Commercial grade 20a switches are usually 120/277v rated so I don’t see a problem using a toggle switch on the control side.


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I agree, but happened to grab a 2 pole version on the THD site when I posted that link earlier. They also offer a single pole that works just as well for this, is a bit cheaper and is what I have controlling my compressor via the control circuit to the contactor. It is duly rated by Leviton for a 240V load, and is self grounding, so the metal box handles that through the conduit.

Simply put, if you have a starter already, I suggest you switch via the control circuit, using whatever switch you like that is suited to the task.

 

[TRWham]

Ok,

I know I will get flamed for this but . . . . at my business I turn the compressor off every night by flipping the breaker. Its a 7 1/2 hp 3 phase compressor. I have been doing that for 30 years and have never had to replace a breaker.

My small 2 1/2 hp compressor at home is on a dedicated outlet and I do the same thing there. I probably only use the compressor a few hours a month, if that. That breaker has been there almost 25 years.

I doubt it's really a problem, especially if the compressor is idle when you power down. Breaking a circuit under load is always harder on contacts than making one because it draws an arc for some small distance as the contacts move apart. That's not really an issue when closing the connection.

 

[On-Wheel]

I used extension cord to mag to motor and the pressure switch that has an off/auto switch.Just did this on a Saylor Beall 705'5hp.The centrifugal unloaded broke so used a pressure switch unloader.
With pressure switch off the mag won't start motor.About $30-35.

 

[Bdflies]

I picked up a couple of 40 amp relays, with 120 vac coils. I have one controlling the feed to the water heater and the other controlling my air compressor starter circuit. Both relays are plugged into the light circuit in my shop. When I turn lights on, in the morning, the compressor and water heater power up. All power down when the lights go off. If I'm gone, or just don't visit the shop for a while, everything stays off. I can remember to turn lights off.
Yeah, the 40 amp relay is overkill for the compressor control circuit. They're not too expensive and just got 2. Works great!

Bill

 

[Git]

Turn off the air at the compressor instead of the electricty

RapidAire sells this valve for $100

http://www.rapidairproducts.com/page/motorized-compressor-shut-off-valve

Or you can buy basically the same thing from Amazon for half the price. I have the one from Amazon and it works great. This particular valve uses DC - so you probably have an old wall wart transformer laying around that you could use. When you power up the valve, it opens, when you cut the power, it closes by a spring. There are a number of ways of turning the transformer on/off - z wave, wifi outlet, light switch etc etc. One advantage of turning off the air is when you turn it back on - you don't have to wait for the compressor to come up to pressure

https://www.amazon.com/gp/product/B00SAFM5U0/?tag=atomicindus08-20

 

[alfredeneuman]

Yes, for a control circuit, I was suggesting it to switch line voltage before we learned he had a mag starter.

Google is your friend>>>>

 

[alfredeneuman]

Turn off the air at the compressor instead of the electricty
One advantage of turning off the air is when you turn it back on - you don't have to wait for the compressor to come up to pressure

Why would it start up when you turn the compressor on electrically?
Unless it leaks it should be in the same state as when you turned it off, and if it leaks it would cycle continuously if you just turned off the air.

 

[rlitman]

Why would it start up when you turn the compressor on electrically?

Unless it leaks it should be in the same state as when you turned it off, and if it leaks it would cycle continuously if you just turned off the air.

Unless the leaks are in the lines (where some degree of leaks are unavoidable) and not in the compressor itself.

 

[EOC_Jason]

If you just want a switch on the control circuit, I would get a simple 240v rated toggle switch and mount it on the box where the mag starter is... Simple & effective.

Otherwise I would mount a disconnect box on the wall next to the compressor and just use that to cut the power completely.

(note: images were just grabbed for reference, make sure you are using ones of proper voltage & amperage for your compressor.)

 

[alfredeneuman]

Unless the leaks are in the lines (where some degree of leaks are unavoidable) and not in the compressor itself.

I always depressurized rubber hoses (via quick disconnects) as a matter of course when I was cleaning up at the end of the day, and ASSumed everyone did too

 

[rlitman]

I always depressurized rubber hoses (via quick disconnects) as a matter of course when I was cleaning up at the end of the day, and ASSumed everyone did too

I have a rubber hose between my compressor and my piping. But I also generally leave my hoses charged. I've had a few polyurethane hoses crack on me, but not the ones that are mesh reinforced. I've also had PVC hoses fail, but never a rubber one.

 

[Git]

I have a 3' synthetic rubber hose to absorb and shock/vibrations from my compressor to the hard lines. I installed my motorized ball valve at the end of the rubber hose. My compressor doesn't leak, not sure what actually does - the system is over 15 years old. My compressor is in a shed about 50' behind my garage and I used to just turn it off by the breaker, but then I added some things to the shed (motion outdoor lights, etc) and I would rather not shut off all the electricity, so the ball valve solved my problem. As others have done - I can turn on the compressor on/off by telling 'Alexa' to do it. Easy Peasy

 

[exranger06]

I'm in the middle of wiring up my compressor. I'm going to install a toggle switch in the garage (the compressor is in the basement on the opposite side of the house). I'm simply wiring the toggle switch in series with the pressure switch. The starter will only turn on if both switches are closed. The only thing is I have to run two extra wires for the switch.