My aircompressor remote switch

Owen · Nov 26, 2009

I bought a 30A DPST switch to turn my air compressor on and off rather than having to turn the rotary switch on it.

I was going to wire the switch inline with the power leads but instead wired it inline with the pressure switch outputs to motor inputs.

Is there anything wrong with doing this? I won't turn it off while the compressor is running. Unless I forget to turn it off and have to run down to the garage in the middle of the night...

The compressor is a Husky 60 gallon Model # VT6314 from Home Depot. I read on the net that the switch should be rated for the HP (which is 3.2HP) rather than the amps. The switch I bough says max 2.4HP...is this not good, even with the way I have it wired?

Thanks

mrb · Nov 27, 2009

Is the pressure switch handling the motor current, or is it switching a contactor? Switches do need to be HP rated, yours would most likely work but would burn out after some time if its switching the entire motor current.

the spyder · Nov 27, 2009

Wire it up to before the pressure switch. I would be concerned about issues with the newer "Chinese" pressure switches many of these machines have.

Owen · Nov 27, 2009

mrb said:
Is the pressure switch handling the motor current, or is it switching a contactor? Switches do need to be HP rated, yours would most likely work but would burn out after some time if its switching the entire motor current.

I don't know...here's a pic

I wired the switch inline with the bottom black and white wires. They go from the black bow with terminals directly to the motor.

Owen · Nov 27, 2009

the spyder said:
Wire it up to before the pressure switch. I would be concerned about issues with the newer "Chinese" pressure switches many of these machines have.

Should I use the switch I have or find one that is rated for at least 3.2HP?

rwhite692 · Nov 27, 2009

I have never liked the idea of using a pressure switch to switch the full load power to a compressor of anything 3HP or larger. I would set that unit up with a magnetic starter and use the pressure switch only to energize/de-energize the coil of the magnetic starter.

Identaltech · Nov 27, 2009

we use low voltage contactor relays in dental offices.
you could make one easly.
only the 24v used to pull in the relay runs to the switch. (you can use a regular light switch and 18g wire)
the relay interupts the power going to the compressor just like a disconnect.

Owen · Nov 27, 2009

Thanks everyone,
Is it easier and/or cheaper to use a contactor rather than a mag starter?

I don't fully grasp the relationship between the pressure switch and the contactor/relay. If I wire a switch or contactor ahead of the pressure switch, doesn't current still flow through it when activated? Isn't my setup the same thing except it's a manual switch?

GeorgiaHybrid · Nov 27, 2009

Owen,

If you are familar with how a relay switch works, the "pressure" switch does nothing more than trigger the mag starter with a lower amperage. This allows the full amperage that runs the motor to go thru the mag starter only and not the pressure switch.

What several people do it wire a "on/off" switch on the lead going to the pressure switch. That way the switch is not handling the full current and can be a low amperage switch. The on/off switch allows current to go to the pressure switch and turn the compressor off/on when in the "on" position and does not allow the pressure switch to turn on the compressor when in the "off" position.

Mr_fixit · Nov 27, 2009

If you're using a "remote switch" you're changing the length of the wire and the voltage drop to the compressor. How much wire are you adding...? A mag starter doesn't do that. Why not just use the breaker as a switch.... Not that that's better, but many people do that.

GeorgiaHybrid · Nov 27, 2009

fixit,

Read his post. Right now he has power coming to his pressure switch and from the switch to the motor. All that he did was buy a 30 amp DPST switch and added it in line between the pressure switch and the motor AT the compressor. I'm like a few others here and don't think that running the full amperage of a larger motor thru a pressure switch is a good idea long term. It works but the contact points can get stuck after time.

I like having the mag starter take the load and everything else being a lower amperage relay circuit. I used to have a buddy do mine but he moved away and with a lot of help from Charles, wired my new compressor up that way when I converted from 3 phase to single phase.

Owen · Nov 28, 2009

Thanks everyone, I'm gonna get a contactor. Probably from autmationdirect since it's 1/3 the price of mcmaster.

Probably being **** retentive here, but since my compressor is 3.2hp, do I get a contactor that's 3hp or the next size up which was 5hp?

My aircompressor remote switch

Owen

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mrb

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the spyder

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Owen

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Owen

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rwhite692

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Identaltech

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Owen

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GeorgiaHybrid

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Mr_fixit

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GeorgiaHybrid

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Owen

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