So I have a 7HP 220 compressor and want to install a wall switch next to my light switch to toggle the system on/off and I'm curious about the best way to go about doing this. From the compressor to the location I want the switch is about 45' so I'm wondering if I could perhaps mount a relay between the hot leg on the pressure switch and have the relay controlled via the wall switch or perhaps one yall have a better solution to the situation.
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7hp 220v compressor on/off wall switch
- Thread starter Jcole2016
- Start date
joe_padavano
Well-known member
If the compressor uses a mag starter, this is easy. I've got a wall switch wired into the mag starter to turn mine on and off.
I'm doing something similar and am using a 110v contactor. The contactor will be between the electric panel and the pressure switch. I'll leave the pressure switch in the ON position, and somewhere convenient, position a new 110v switch to control the coil on the contactor.
wyliesdiesels
Well-known member
Does your compressor have a mag starter? At 7.5hp (7HP is not a standard size) it most likely does...
wyliesdiesels
Well-known member
Contactor needs to be rated for 240v not 120v since it will see both sides of the circuit.I'm doing something similar and am using a 110v contactor. The contactor will be between the electric panel and the pressure switch. I'll leave the pressure switch in the ON position, and somewhere convenient, position a new 110v switch to control the coil on the contactor.
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It's actually a 3phase contactor rated for 600v with a 110v coil.Contactor needs to be rated for 240v not 120v since it will see both side of the circuit.
I'm using two legs to power the compressor and the 3rd leg is being used for a 110v light to help me remember to turn off the compressor.
ptt49er
Well-known member
I picked up a HVAC contactor that switches two poles...
Ran an extension from my overhead lights to a small metal enclosure with the contactor.
That way my compressor is only on if my lights are on.
Ran an extension from my overhead lights to a small metal enclosure with the contactor.
That way my compressor is only on if my lights are on.
wyliesdiesels
Well-known member
EDIT: The problem with that method is that the indicator lamp will only be lit when the compressor motor is on thus making it pointless...It's actually a 3phase contactor rated for 600v with a 110v coil.
I'm using two legs to power the compressor and the 3rd leg is being used for a 110v light to help me remember to turn off the compressor.
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While I don't care for the practice, it's not against code to switch only 1 leg of a 240V single phase load, or 2 legs of a 3 phase load, as long as it is not a disconnect, which a contactor is not, and is very common in HVAC equipment, but the OP did say 220V which is line to neutral.
Noltz
Well-known member
While I don't care for the practice, it's not against code to switch only 1 leg of a 240V single phase load, or 2 legs of a 3 phase load, as long as it is not a disconnect, which a contactor is not, and is very common in HVAC equipment, but the OP did say 220V which is line to neutral.
Nevermind. I'm responding to the wrong person.
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Cruzan80
Well-known member
You guys do realize Imagineer (using a 3ph-coil) is not the OP, right?
I am putting money on the SPL HP rating allowing a sticker to say 7hp.
I am putting money on the SPL HP rating allowing a sticker to say 7hp.
wyliesdiesels
Well-known member
That guy isnt the OP and connecting the lamp in the manner he has it connected is pointless. Read above...He's not saying to switch only 1 leg of the 240 load. The contactor has 3 poles controlled by a 120v coil. Of the 3 poles two will make & break both legs of the 240v compressor circuit, and the 3'rd carries 120v to an indicator lamp to show the contactor is energized. Wylies saying don't bother using the 3'rd pole and instead just use the 120v coil-controlling switched circuit to (also) energize the indicator lamp.
The OP wants a snap switch at the door and that would need to be in-line with the coil circuit and rated for 240v...
Noltz
Well-known member
No, No I did not. Thanks!You guys do realize Imagineer (using a 3ph-coil) is not the OP, right?
I am putting money on the SPL HP rating allowing a sticker to say 7hp.
TRWham
Well-known member
Not if the light is powered from the line side of one of the feeder contactor poles back through a neutral (which presumably you have handy given the 120 V control voltage). Then the light is only made when the control switch is on and the feeder contactor is pulled in. It's essentially using the 3rd pole as an auxiliary contact to sense the state of the feeder contactor. The operation of the compressor contactor or pressure switch will not impact this function.EDIT: The problem with that method is that the indicator lamp will only be lit when the compressor motor is on thus making it pointless...