120v off of 240v Compressor Switch

[Ironken]

I have a long shot here.....I have an automatic drain valve for my compressor. I wanted to cut a fat hog here since there is not a 120v outlet near my compressor and connect the drain to one leg of 240v on my compressor pressure switch. Is there a correct way to do this?

[DXF]

I have a long shot here.....I have an automatic drain valve for my compressor. I wanted to cut a fat hog here since there is not a 120v outlet near my compressor and connect the drain to one leg of 240v on my compressor pressure switch. Is there a correct way to do this?

Yes, that is how I wired my automatic drain so it is on when the compressor is on. I wired it to one side of the on-off switch.

Dave Hanks

[acourtjester]

double post

[acourtjester]

You can hook it up with one hot lead and one neutral lead I would put the hot lead through the switch.
this is how you home outlets are wired, the breaker box has 220 input with neutral and ground. Each of the outlet breakers control the hot one hot wire and the neutral and ground go to the outlets too so its one leg to neutral for power to 110 volt items. A double breaker has 2 hot leg with neutral to the item like your compressor. By hooking to one hot and neutral for you drain valve you are doing the same thing as in the breaker box. Don't forget the ground, I would hook the wires to an outlet receptacle in a electrical box and then just plug the drain valve in that. You may want to use a GFCI receptacle.

power.JPG

[ben de lappe]

Got to say this is a fine example of what I like about this forum. I'd venture to say most of us here aren't gifted in the electrical department, strong personal reference here. Many years ago found myself in a predicament with 110 volt welding machine/plasma cutter on job sites where the only electrical connection was an electrical box dropped straight from the power line. Thankfully an old friend of mine Ken, retired union electrician straightened me out by informing me in terms I could understand that one "leg" of a 220 circuit will give you 110.
Running a 110 V plasma from a generator...discussion for another day.

[WyoGreen]

I'm going to qualify what the guys up above said. It depends on what cable they ran to the compressor. Some people just run 2 hot wires (white and black) and a ground wire to the compressor. (The white wire should be taped or marked to indicate it is being used as a hot wire.) In such a case, there is no neutral wire to break out out the 110V leg. You need a 3 wire cable to the compressor, 2 hot legs, red and black wires, and a neutral, white wire (there is also a bare ground wire). Then you can pick up the white wire and either the red or black wire to get your 110V.

Steve

[Ironken]

I'm going to qualify what the guys up above said. It depends on what cable they ran to the compressor. Some people just run 2 hot wires (white and black) and a ground wire to the compressor. (The white wire should be taped or marked to indicate it is being used as a hot wire.) In such a case, there is no neutral wire to break out out the 110V leg. You need a 3 wire cable to the compressor, 2 hot legs, red and black wires, and a neutral, white wire (there is also a bare ground wire). Then you can pick up the white wire and either the red or black wire to get your 110V.

Steve

Thank you all for the suggestions and Wyogreen hit on my issue of which I couldn't articulate. I only have 3 wires running to the compressor B,W and G. No neutral for the 120v circuit. Thank you guys for the help!

[DXF]

I'm going to qualify what the guys up above said. It depends on what cable they ran to the compressor. Some people just run 2 hot wires (white and black) and a ground wire to the compressor. (The white wire should be taped or marked to indicate it is being used as a hot wire.) In such a case, there is no neutral wire to break out out the 110V leg. You need a 3 wire cable to the compressor, 2 hot legs, red and black wires, and a neutral, white wire (there is also a bare ground wire). Then you can pick up the white wire and either the red or black wire to get your 110V.

Steve

Yes, when I wired the on-off switch I had a red and black wire as hot and white as neutral. Pretty simple. I bought a booklet at Sears over 40 years ago that explained house wiring in simple terms and diagrams......haven't had a shocking experience yet and I'm no expert or gifted as Ben de lappe said.....I am determined.

Dave Hanks

[SegoMan DeSigns]

Here's one for the what it's worth dept, I have a standard light switch next to the compressors mag relay on / off. The switch runs the tank drain when the switch is turned on it dumps the tank then goes into the programmed cycle, this allows me to flip it several times to drop the overnight condensation..

[WyoGreen]

I do have an idea that might make this work. It would involve getting a 240v to 120V step-down transformer. The wattage of the transformer would have to match the input wattage of your tank drain. Prices run from about $30 to over a $100, depending on wattage. There's a bunch on Ebay.
https://www.ebay.com/sch/i.html?LH_CAds ... =&_fosrp=1

[djreiswig]

You could just run a neutral wire to your compressor. Or just wire up a 120v outlet.

[Ironken]

I do have an idea that might make this work. It would involve getting a 240v to 120V step-down transformer. The wattage of the transformer would have to match the input wattage of your tank drain. Prices run from about $30 to over a $100, depending on wattage. There's a bunch on Ebay.
https://www.ebay.com/sch/i.html?LH_CAds ... =&_fosrp=1

Thank you all for the ideas! Wyogreen, I think that your rout is the one for me. I'm on it.

Thanks again, everybody!

[SegoMan DeSigns]

US 240 is two legs of 120, the third is 208 if it's three phase. Your contactor switch has a leg for each one of the voltages needed. The pressure switch is probably 120 get out your voltmeter and do some checking..