240v switch for my 7hp/60gal air compressor?

[Daubs]

Setting up the 40'x30' shop, want to put my air compressor in the back corner. Wired on 30 amp circuit with 10/2 Romex to the outlet.

I'd like to put a switch in front of shop, near my workbench to turn the air compressor on and off.

Leviton makes a 30 amp double-pole switch. Or would a single-pole switch work?

Some pictures...


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[bggrnchvy]

My BIL does that with his 5hp compressor. It's not truly the best option, but it does work.

The correct solution commonly applied is a mag starter and a regular switch on the control side remotely wired.

 

[sberry]

You need a pic of the motor data plate. While that sticker says 7 hp its really 3.

 

[strutaeng]

I think that should work. The switch is rated for 30A and 10CFM compressor is those motor HP rating listed as "SPL", but based on the 15A draw, turns out to be more or less like a 3.5HP.

7HP is marketing advertising!

There are some members here that are electrical professionals, and maybe they can chime in...

The only problem than can arise is turning the switch off while the machine is pumping up and trying to restart. It will have a hard time due to the loaded condition. Just flip the lever on the pressure switch to off to bleed the air and off you go.

 

[wyliesdiesels]

Setting up the 40'x30' shop, want to put my air compressor in the back corner. Wired on 30 amp circuit with 10/2 Romex to the outlet.

I'd like to put a switch in front of shop, near my workbench to turn the air compressor on and off.

Leviton makes a 30 amp double-pole switch. Or would a single-pole switch work?

Some pictures...

That switch will not work because it is rated for 2HP max.

Also, a single pole switch would not work.

Whatever you use needs to be rated for the motor HP which in your case is around 3HP.

This switch would work for you:

https://www.leviton.com/en/products/ms302-ds

 

[cabranch47]

I used a definite purpose 40 amp contactor with a 120V coil on mine. I wired it to the shop lights so that it is off when I am not in there. I don't turn it off while running. Feel better about it as there is a small leak that I have not been able to find and it kept cycling when I was away.

 

[Daubs]

Motor label...

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[PoorOwner]

I use this one to shut motors which is probably the boxed version that WylieDiesels recommended. The HP is written on the box itself, also have a hole for padlock.

https://www.amazon.com/gp/product/B003GIS2O4/?tag=atomicindus08-20

 

[navycryppie]

2.98 KW output means it's a 4HP motor.

 

[Citation]

Op, just for reference, the problem with a normal switch is due to the large voltage spike associated with turning the motor off. When you turn a motor off you can have a large back EMF spike that is much higher than the normally switched voltage. Basically a normal 30A switch can handle the running current but using it to turn the motor off could case problems. In theory if you never switched the compressor off until the pressure switch turned the motor off this wouldn't be an issue. However, given the switch below is not much more you should just get the proper switch.

BTW, as others have noted the unloader valve is built into the compressor's pressure switch so if you turn the compressor off at the wall switch you will either have to manually cycle there compressor switch to trigger the unloader valve or wait for the pressure to drop naturally. If this is a problem you could also install some type of alternative/secondary unloader. One type would be a pin hole orifice. Some really cheap compressors use this instead of an actual valve. It slightly slows the full rate and does require a few seconds to bleed down. The other option would be an AC air valve that is closed when powered. Thus any time the wall switch is on the valve is shut. The normal unloader works in this case. If the wall switch is turned off the valve opens. If your intent is just too make sure there compressor is off at the end of the day this is all overkill.
https://www.amazon.com/dp/B002MPQ51O/?tag=atomicindus08-20

 

[Falcon67]

2.98 KW output means it's a 4HP motor.

Yep, based purely on nameplate rating. (15A x 240v) / 745 watts per HP = 4.

Most of those motors are more like 3.2HP or so. 7 HP = LOL, sure. They should have gone with the LRA - that's like 29 HP.

 

[Daubs]

Appreciate the input here!

Ordered up the Leviton MS302-DS switch.

Should work good, as I always wait for the compressor to finish cycle before shutting off power.

Thanks again! D.

 

[Daubs]

Switch arrived, and got it wired in last night. Thanks for all your suggestions.




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[mike93lx]

Connect the ground to the switch ground screw

Edit: my bad, looked it up after posting, should have done it before. Non grounding switch

 

[Daubs]

No ground screw on this switch...

 

[pattenp]

240V, mark white wires as black or red. The NM looks like it's not fasten properly to the stud and the jacket doesn't appear to enter the box enough.