Compressor Switch

[stankp]

I have searched the site and have not found my answer directly.
Here is the question; I have an old single phase 5hp compressor. It already has a magnetic starter but no actual switch to speak of. To turn it on I plug it in. This is obviously less than ideal. I am wondering what type of switch I should install here? Should I just install a 40 amp safety switch? Admittedly, I know enough about electrical things to be wildly dangerous, so please keep the comments in laymen's terms..

Thanks!

 

[pattenp]

That compressor should be hardwired, no plug. The cheapest route is to use a Square-D QO 60A AC disconnect, it is rated to 10HP. They are sold at HD and Lowes for about $16.

http://www.homedepot.com/p/Square-D...otection-QO200TRCP/202353314?N=5yc1vZbm0hZal2

 

[Zrexxer]

Even if it's hardwired, you can wire an on-off switch in series with the mag starter's coil. That's a very low current circuit and you could even use a light switch to control it. The other part of the mag starter is what handles the high current.

 

[38 Dodge Coupe]

My compressor has the on/off switch as part of the pressure switch connection.

 

[Zrexxer]

My compressor has the on/off switch as part of the pressure switch connection.

Well, yes, the pressure switch is what normally controls the mag starter's coil, so the switch would be wired in series with both the coil and the pressure switch.

 

[wyliesdiesels]

DEFINTELY hardwire that thing!

And u could install a light switch by your door and wire it in series with the pressure switch...

 

[K Powers]

hey guys, I'm working on a similar project. I'm planning on installing a disconnect similar to what pattenp has above for a safety shutoff. could I also use the disconnect as an on off or is it better to put a switch in the pressure switch to mag starter? would like to have an on off switch if needed, but don't want any unintended consequences e.g. motor or mag starter damage

 

[pattenp]

hey guys, I'm working on a similar project. I'm planning on installing a disconnect similar to what pattenp has above for a safety shutoff. could I also use the disconnect as an on off or is it better to put a switch in the pressure switch to mag starter? would like to have an on off switch if needed, but don't want any unintended consequences e.g. motor or mag starter damage

You can use the Square-D QO200 as an ON/Off switch but I don't know what the duty cycle is on that switch.

 

[K Powers]

Don't have the model number but I was looking at the 60 amp blade style disconnect. Never thought of duty cycle is that referring to how long the switch is in the on pos?


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[pattenp]

Don't have the model number but I was looking at the 60 amp blade style disconnect. Never thought of duty cycle is that referring to how long the switch is in the on pos?


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How many times the switch can be flipped on and off before wearing out the switch.

 

[K Powers]

I get it because it's switching the whole load. How would I size a switch interrupt the pressure circuit?


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[wyliesdiesels]

I get it because it's switching the whole load. How would I size a switch interrupt the pressure circuit?


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Does your compressor have a mag starter?

 

[Zrexxer]

I have an old single phase 5hp compressor. It already has a magnetic starter

Does your compressor have a mag starter?

I'm guessing you didn't even make to the second line of the OP's post...

 

[K Powers]

[ QUOTE=wyliesdiesels;4538134]Does your compressor have a mag starter?[/QUOTE]

Yes it does have a mag starter. Didn't want to hijack the ops thread but thought it was a similar enough question



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[pattenp]

I'm guessing you didn't even make to the second line of the OP's post...

He wasn't responding to the OP.

 

[toplessHO]

if its close and in sight of the panel that feeds it you dont need a disconnecting means.
But it is cheap enough..... Mag starter and a pressure switch with on/off switch is the accepted means

 

[Zrexxer]

He wasn't responding to the OP.

 

[Norcal]

If a magnetic starter is used, a simple switch* can be used to interrupt the control circuit, the load is just the coil of the starter, which will vary depending on the size of the starter but not enough to worry.

*Simple switch could be a residential grade toggle switch, or better yet a selector switch used for industrial control like the Allen-Bradley ones shown below.

 

[ForceFed70]

I looked into this myself when I wired my 1P 5HP compressor.

I ended up getting a 50A subpanel with included breaker. Did the same thing as a disconnect and was 1/3 the price. Supposedly it'll handle more cycles too.

 

[sberry]

Most of these don't need extra switches. Just more connections and **** on it.

 

[AP514]

I never thought of a duty cycle on my safety switch....where would it say ?

http://www.homedepot.com/p/GE-30-Am...witch-TGN3321CP/100674081#product_description

 

[K Powers]

If a magnetic starter is used, a simple switch* can be used to interrupt the control circuit, the load is just the coil of the starter, which will vary depending on the size of the starter but not enough to worry.

*Simple switch could be a residential grade toggle switch, or better yet a selector switch used for industrial control like the Allen-Bradley ones shown below.

when installing the switch which line do you interrupt to the pressure switch M or L?

 

[wyliesdiesels]

when installing the switch which line do you interrupt to the pressure switch M or L?

M or L? Huh?

 

[stankp]

Sorry for the lag in response guys. Thanks for all the thoughts.
Yes, I want to eliminate the plug and hardwire. Right now I am turning it on and off by the circuit breaker which I know is less than ideal.
Here is a photo of the mag. switch, it is in it's own box. The orange wire is the one to the plug. The red, black and blue head to the compressor.
Admittedly I have no idea where to wire a regular switch in on this. Zrexxer, can any you give me an idea of what posts to go from for switching?

 

[K Powers]

M or L? Huh?

Line or motor, the wires running to pressure switch


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[wyliesdiesels]

Line or motor, the wires running to pressure switch


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O duh....i was tired...