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7.5HP disconnect

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bochnak

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Looking for an indoor, non fusible, with on/off switch, single phase disconnect.

This will be used to turn compressor on/off when not in garage.

Thanks,
Matt
 
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rlitman

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930dreamer

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Not sure if this is NEC legal, what about a used three phase disconnect and use two of the lines? I see these all the time on FB, CL etc and are usually for larger hp motors.
 

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alfredeneuman

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930dreamer said:
Not sure if this is NEC legal, what about a used three phase disconnect and use two of the lines? I see these all the time on FB, CL etc and are usually for larger hp motors.
Click to expand...

The problem with 3 pole disconnects is they're rated for that HP at 3 phase, not single phase. They aren't labeled or listed for single phase
 
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alfredeneuman

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wyliesdiesels

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Lightning rod said:
This is what i use for my compressor

https://www.homedepot.com/p/Leviton...ble-Pole-Switch-White-R62-03032-2WS/100356941
Click to expand...

That is rated for 2HP. It wont work for the OP

Whats the HP rating on your compressor?

bochnak said:
I have this sort of thing for my 5hp (switch made by bryant).

Problem is that going to 7.5hp requires #6 wire and it will be very difficult to stuff in a 4" square box. Assuming they make a version rated for 7.5hp.
Click to expand...

You have a snap switch for a 5HP motor? Its probably not rated for the HP youre subjecting it to.
 
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rlitman

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alfredeneuman said:
The problem with 3 pole disconnects is they're rated for that HP at 3 phase, not single phase. They aren't labeled or listed for single phase
Click to expand...

Good point. You have to read the label. Sometimes they are.

alfredeneuman said:
General-Duty disconnects aren't HP rated. Heavy-Duty ones are....and cost more than General-Duty ones.
Is the breaker within sight and not more than 50' away from the equipment?
If so, it would qualify as the disconnecting means
Click to expand...

My $12 disconnect has a 15 horsepower rating right on it. From what I've seen, HP ratings are something you need to open the box and look for. It's just not something they print on the outside.
 
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TonyJ

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If your running a 7.5 hp compressor then your likely running a magnetic starter also. If so then just put you a switch in line with the coil in the starter and use that to turn it on and off with. And it won’t cost a fortune because the coil runs on very low amps so a small switch can be used


Tony
 
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rlitman

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TonyJ said:
If your running a 7.5 hp compressor then your likely running a magnetic starter also. If so then just put you a switch in line with the coil in the starter and use that to turn it on and off with. And it won’t cost a fortune because the coil runs on very low amps so a small switch can be used


Tony
Click to expand...

That would be the easiest way to turn the compressor off at night. It doesn't require any HP rating, and makes it potentially simple to mount the switch remotely as well.
 
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tdkkart

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rlitman said:
That would be the easiest way to turn the compressor off at night. It doesn't require any HP rating, and makes it potentially simple to mount the switch remotely as well.
Click to expand...

Exactly what i did, the controlling switch is one of my light switches by the door, when I leave the shop there's no way for the compressor to run.
 
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exranger06

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I also recommend switching the coil of the starter. That's what I did on mine. I have a remote toggle switch to turn it on and off from the garage. The compressor is in the basement on the other side of the house.
 
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rlitman

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exranger06 said:
I also recommend switching the coil of the starter. That's what I did on mine. I have a remote toggle switch to turn it on and off from the garage. The compressor is in the basement on the other side of the house.
Click to expand...

Well, I won't say there's anything wrong with this approach, but I don't actually ever shut my compressor off (though a shutoff to the starter is on my to-do list). I have a motorized ball valve at my tank that I shut off remotely. When it's off there are no leaks whatsoever, so it can sit for weeks without cycling, and it doesn't immediately run when I turn it on.

Had I only shut down the power, it would have to pump all the way back up each time I use it.
 
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Ilikeike

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I have a knife switch type disconnect on my little compressor shed outside my garage, but since I'm quarantined bored right now, and thinking of garage stuff to do, I was thinking about a remote mounted E-Stop mounted in my garage by the door into the house so I wouldn't forget to kill it, then just run to a contactor out by the compressor before the service disconnect.


Hmmm:headscrat
 

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bochnak

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Here is a toggle switch with 60A / 20hp rating. Question is what do you house it in with enough room for wires?

https://www.automationdirect.com/ad...ntrollers_-z-_disconnects_(30-60_amps)/60002d

l_60002d.jpg
 
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exranger06

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rlitman said:
Well, I won't say there's anything wrong with this approach, but I don't actually ever shut my compressor off (though a shutoff to the starter is on my to-do list). I have a motorized ball valve at my tank that I shut off remotely. When it's off there are no leaks whatsoever, so it can sit for weeks without cycling, and it doesn't immediately run when I turn it on.

Had I only shut down the power, it would have to pump all the way back up each time I use it.
Click to expand...

I don't really HAVE to shut mine off. My system is pretty much leak free. I leave all of the piping and hoses fully pressurized 24/7. If I left the switch turned on 24/7, the compressor would probably only turn on once a month (that is, if I don't actually use it). But I like to turn the power off just in case a leak ever springs up.
 
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Lightning rod

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wyliesdiesels said:
That is rated for 2HP. It wont work for the OP

Whats the HP rating on your compressor?



You have a snap switch for a 5HP motor? Its probably not rated for the HP youre subjecting it to.
Click to expand...

Since i retired last year i find that my brains are slowly turning to mush to the extend that i don’t always fully explain what my recommendations are based on.
You guys are correct in that the proposed switch is not rated to switch “in and out” a 7.5 HP compressor.
I assumed that the compressor already had a magnetic starter on it and the OP Was looking for a way to make sure that the power was off to the compressor when he wasn’t around.
The proposed switch will not be used to switch the compressor directly
Only when the compressor is not running.
Thats what i did in my garage.
 
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