Compressor off when shop light are off

[RegeSullivan]

I want my 120V oilless compressor to turn off when my shop lights are turned off but turn on (deliberately) only when shop lights are on. I intend to use a 120 volt 15A magnetic switch an a 120V 30A contactor. Please review my (poorly done) drawing and make suggestions.

 

[matt_i]

Seems good to me. Where did you source the on-off switch asm?

 

[mike93lx]

Seems like it would be a lot easier to just add an outlet on the lighting circuit, if it has the capacity.

 

[mm08822]

Schematic is ok.

The contactor needs to be HP rated @120vac. Choose a different one.

 

[mm08822]

Seems like it would be a lot easier to just add an outlet on the lighting circuit, if it has the capacity.

Yes, but lighting flicker for sure. Maybe loss of lights at wrong time if breaker trips.

 

[wssix99]

That will work, but I would put your switch on the hot leg that goes from the contactor to the compressor. (So if the contactor fails-on, you'll still have the switch to cut the compressor off.)

The contactor will come on every time you turn on the lights, but that shouldn't be a problem. If you still don't want the "click" you can just install 2 switches.

 

[TRWham]

Do not break the neutral through the contactor.

I would skip the contactor, and run this as a 20A multi-wire branch circuit (MWBC) through a single 2 pole 30A switch, assuming that switch is rated to handle your compressor. Each pole would break one line (one for the compressor outlet and one for the lights), while the neutral would be shared. The 2 circuit breakers feeding the circuit would be tied so there can be no question of one remaining hot if the other needs service.

 

[alfredeneuman]

The contactor needs to be HP rated @120vac. Choose a different one.

The contactor is rated for 30A Full load amps (as in motor load) and a 40A Resistive load.

 

[RegeSullivan]

Seems good to me. Where did you source the on-off switch asm?

I like that you can easily remove the paddle. I have several on 1/4 and 1/3 HP machines and they have been reliable so far. Hard to beat for $10.00. https://www.amazon.com/gp/product/B01IEM2DSM/?tag=atomicindus08-20

The contactor needs to be HP rated @120vac. Choose a different one.[/QUOTE]
I was afraid of that, I can not find much information regarding contactors and this one came with no schematic . The compressor is a craftsman 6HP that runs on a 15 amp circuit. So obviously not really a 6HP motor. What is the worst that is likely to happen if it fails?

That will work, but I would put your switch on the hot leg that goes from the contactor to the compressor. (So if the contactor fails-on, you'll still have the switch to cut the compressor off.)

The contactor will come on every time you turn on the lights, but that shouldn't be a problem. If you still don't want the "click" you can just install 2 switches.

There is a switch on the compressor (between the contactor and compressor) I should have put that in the drawing in the drawing.

Do not break the neutral through the contactor.
- Thanks. - My intuition told me that was wrong.

I would run this as a 20A multi-wire branch circuit (MWBC) through a single 2 pole 30A switch, assuming that switch is rated to handle your compressor. Each pole would break one line, and the neutral would be shared. The 2 circuit breakers feeding the circuit would be tied so there can be no question of one remaining hot if the other needs service.

How would that allow me to signal the contactor off the 15A lighting circuit?

 

[TRWham]

- how would that allow me to signal the contactor off the 15A lighting circuit?

I edited my post to make it more clear. You would not need the contactor anymore, because the switch would break the circuit directly.

 

[RegeSullivan]

I edited my post to make it more clear. You would not need the contactor anymore, because the switch would break the circuit directly.

I am familiar MWBC's and I understand the safety concern. Unless it is not code compliant maybe I could tie the two breakers together to alleviate the safety concern. Or, maybe I am missing the point and don't understand how your suggestion will kill the compressor when the lights to the shop are turned off. The lights are on a 15A circuit and controlled by two 3-way switches. Are you suggesting rewiring the lights? Even if I was starting from scratch and did a 20 amp lighting circuit would it be code compliant to have a dedicated outlet and lighting or non-dedicated circuits in the MWBC?

Another idea would be to put a 24V transformer on the light circuit to signal the controller since the one I have seems to be underrated anyway???

 

[TRWham]

I was under the mistaken impression this was new work, and you had not previously mentioned 3 way switches for the lights. Given that, the device I had in mind to switch both feeders and avoid the relay will not work. You can certainly find a suitable contactor with a 120V coil. You will just need to pick up your control voltage from the leg that feeds the lights, and figure out where to put all this stuff.

As far as NEC is concerned, it's just an outlet. It is not required to be dedicated, so it should be no issue that it is tied to other loads. There is also no prohibition against 20A lighting circuits, nor mixing lighting and receptacles (though some mistakenly believe so).

ETA: Make sure you take the control voltage back to the neutral for the lighting circuit.

 

[wyliesdiesels]

The contactor is rated for 30A Full load amps (as in motor load) and a 40A Resistive load.

But that is NOT a HP rating.

The contactor specifically needs to have a HP rating equal to or greater than the motors HP rating.

 

[mm08822]

The contactor is rated for 30A Full load amps (as in motor load) and a 40A Resistive load.

See NEC 430.83 (A)(1) …….shall have horsepower ratings at the application voltage not lower than the horsepower rating of the motor.

The contactor needs to be HP rated @120vac. Choose a different one.

I was afraid of that, I can not find much information regarding contactors and this one came with no schematic . The compressor is a craftsman 6HP that runs on a 15 amp circuit. So obviously not really a 6HP motor. What is the worst that is likely to happen if it fails?

One of 2 failure modes - stops conducting and comp stops or contacts weld closed and the compressor PS provides exclusive control regardless of lights on/off.

Op, Consider AutomationDirect part # WDP40-2L-120 ($10.50) or WDP40-3L-120 ($16.50). This one is over-sized and should give long life. These both have HP rating @120vac.



And if you want to spend more $, find one UL/ETL rated.


There is a switch on the compressor (between the contactor and compressor) I should have put that in the drawing in the drawing.

How would that allow me to signal the contactor off the 15A lighting circuit?[/QUOTE]

But that is NOT a HP rating.

The contactor specifically needs to have a HP rating equal to or greater than the motors HP rating.

at the operating voltage too.

 

[RegeSullivan]

But that is NOT a HP rating.

The contactor specifically needs to have a HP rating equal to or greater than the motors HP rating.

I just can't find a contactor with a specific "HP" rating. I have not found much relevant information regarding contactors, at least not information I can understand. The contactor I have has a AC-3 rating, 15A 277 volts that I assumed would be fine since my compressor is a 6HP oil-less Craftsman (119.165500) rated to run on a 15A breaker or slow blow fuse. Obviously it's not 6HP because it only requires a 15A 120V circuit. That said, I have not found the actual amperage draw or peak in the manual or searching on the web and my amp meter only goes to 16 amps so I didn't want to chance melting it. It's just one of the cheapie kill-o-what type meters.

Perhaps someone can tell me what contactor specifications I need to look for. The one I have says "SA-1.5P-30A-120V", "Coil 120V AC", AC-1 20 AMP 277VAC", AC-3 15AMP 277VAC". There is a picture in my original post if you want to see more information.

 

[mm08822]

I just can't find a contactor with a specific "HP" rating. I have not found much relevant information regarding contactors, at least not information I can understand. The contactor I have has a AC-3 rating, 15A 277 volts that I assumed would be fine since my compressor is a 6HP oil-less Craftsman (119.165500) rated to run on a 15A breaker or slow blow fuse. Obviously it's not 6HP because it only requires a 15A 120V circuit. That said, I have not found the actual amperage draw or peak in the manual or searching on the web and my amp meter only goes to 16 amps so I didn't want to chance melting it. It's just one of the cheapie kill-o-what type meters.

Perhaps someone can tell me what contactor specifications I need to look for. The one I have says "SA-1.5P-30A-120V", "Coil 120V AC", AC-1 20 AMP 277VAC", AC-3 15AMP 277VAC". There is a picture in my original post if you want to see more information.

Right here from the post above.......

"Op, Consider AutomationDirect part # WDP40-2L-120 ($10.50) or WDP40-3L-120 ($16.50). This one is over-sized and should give long life. These both have HP rating @120vac.

Screenshot_07232018.JPG

And if you want to spend more $, find one UL/ETL rated."

 

[RegeSullivan]

Right here from the post above.......

"Op, Consider AutomationDirect part # WDP40-2L-120 ($10.50) or WDP40-3L-120 ($16.50). This one is over-sized and should give long life. These both have HP rating @120vac.

Screenshot_07232018.JPG

And if you want to spend more $, find one UL/ETL rated."

OK, I can see it on the side of the contactor "HP 2 3" on my computer... Sorry I could not see that on my phone. I will order the one you suggest to complete my project. For future reference what in the spec told you it had a HP rating. Thanks for all the help.

 

[mm08822]

OK, I can see it on the side of the contactor "HP 2 3" on my computer... Sorry I could not see that on my phone. I will order the one you suggest to complete my project. For future reference what in the spec told you it had a HP rating. Thanks for all the help.

The column labeled Horsepower..........under 1 Phase, 120 VAC believe it or not!

It's 2 hp for 120vac and 3 hp for 204/277vac

refer to cut sheet .... https://cdn.automationdirect.com/static/specs/dpcontactors.pdf

 

[TRWham]

Okay people, this is most likely a listed appliance, and if so, is covered by Exception 3 to 430.6(A)(1), and 430.109(F) also applies and in turn points to 422.33. UL almost always trumps the NEC so there will be exceptions for listed equipment.

 

[Git]

Turn of the AIR with this motorized ball valve

Install the valve at or near the compressor. Run an outlet from your lighting circuit close to your compressor /valve. This particular valve is 110v - you plug it into the outlet and it opens when the circuit is energized and closes when it is not. Done. Easy Peasy

https://www.amazon.com/dp/B00PVPFAUE/?tag=atomicindus08-20

 

[Milton Shaw]

I too used a motor driven ball valve to turn my air off. I hooked it to the compressor with a whip hydraulic hose so that it would never leak upstream from a broken hose. These valves turn on the air slowly so that there is no air hammer from instant air pressure like a solenoid valve would give. I have had mine for about 6 months now and love always having air pressure when I go in and turn the lights on instead of having to wait for compressor to build up air from line leaks. No system with 200 foot of lines and a dozen air drops with quick couplers and any hose reels is going to be completely leak free. I have checked all fittings for leaks that I can get too with an ultrasonic leak detector and bubble leak but still have leaks.

 

[Git]

I agree

I should add, that they also make these in low voltage. If you do not have an outlet near your compressor, all you need is some sort of 'wall wart' type transformer (12 to 24 v DC) and run two low voltage wires over to the ball valve. If you want to get fancy - get some sort of 'smart' switch that you can control with a remote, Amazon Echo, etc

 

[larry4406]

Waking up this thread.

Anyone used the 3/4" motorized valve from RapidAir Products? It is rated up to 230 PSI
https://www.rapidairproducts.com/sh...ries/3-4-female-npt-compressor-shut-off-valve
https://www.rapidairproducts.com/wp-content/uploads/2019/04/elect-schematic-.pdf
https://www.youtube.com/watch?time_continue=1&v=YVJ0KjuWhTI&feature=emb_logo

Summit Racing shows it as less expansive
https://www.summitracing.com/parts/raa-cp-0190

The unit that Git linked is max rated at 145 psi and 1/2".

 

[nadogail]

Thanks for sharing.l

 

[larry4406]

...I too used a motor driven ball valve to turn my air off. I hooked it to the compressor with a whip hydraulic hose so that it would never leak upstream from a broken hose...

So you have compressor => whip hydraulic hose => motor driven ball valve? If the whip hydraulic hose leaks/fails then the compressor runs as the pressure switch turns it on?

I like these motorized ball valves but am thinking I would also like to interrupt the pressure switch so there are 2 means to shutoff. I am planning on installing a 120V switched plug off the lighting circuit for the ball valve and would like to use it somehow to make/break the pressure switch circuit as well.

I have a Puma TUE-7580 7.5HP compressor with a Square D 8911DPS042 starter and LEFOO LF10-4H pressure switch. Is the starter basically a contactor and just using 120V off one 240V leg thru the pressure switch to drive the contactor? That's what the wiring schematic seems to show (using ground and the black leg in my case).

Is it possible to drive the 120V contactor off the separate 120V switched plug? Or am I better off using a 120V relay/contactor to make/break the pressure switch circuit?

 

[Milton Shaw]

The hydraulic hose has a 3500 psi working rating so I don't think it will ever fail on a 175 psi max air line. That's why I control the air and not the compressor. Almost any contactor could be used to break the line from the pressure switch to the main magnetic switch as the load on that line would be less than 1 amp just on the control side of the circuit. I like having a full air tank when I turn the lights on. When you turn the whole compressor off any downstream leak will leave you with a long run time before you can use air. All systems will eventually have downstream leaks as even the best hoses/fitting will eventually wear and leak. I have seen companies that drain the tanks every day and leave the drains open all night long, they can't do anything for 20 minutes each morning as the compressors finally fill their 120 gallon tanks with hot air. All that hot air cools and lets more moisture in the tank than gets in there during a day of regular use.

 

[larry4406]

The hydraulic hose has a 3500 psi working rating so I don't think it will ever fail on a 175 psi max air line. That's why I control the air and not the compressor. Almost any contactor could be used to break the line from the pressure switch to the main magnetic switch as the load on that line would be less than 1 amp just on the control side of the circuit. I like having a full air tank when I turn the lights on. When you turn the whole compressor off any downstream leak will leave you with a long run time before you can use air. All systems will eventually have downstream leaks as even the best hoses/fitting will eventually wear and leak. I have seen companies that drain the tanks every day and leave the drains open all night long, they can't do anything for 20 minutes each morning as the compressors finally fill their 120 gallon tanks with hot air. All that hot air cools and lets more moisture in the tank than gets in there during a day of regular use.

Thank you and understood. I have a hydraulic hose as a whip as well - cheap and way over capacity.