# Solenoid Wiring



## jbolt (Apr 21, 2015)

I'm wiring a solenoid valve into my mill for a mist system. I just want to make sure I understand the wiring diagram in the attached PDF. 

My take is one black wire goes to the positive on the 24vac power supply, the other black wire goes to the negative terminal on the 24vac power supply and yellow/green goes to safety ground?

Jay


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## Tony Wells (Apr 21, 2015)

AC power supplies are not polarized. There is no positive and negative in the conventional sense. If your PS is AC, doesn't matter which one you connect. I gather you are switching the line side of the PS?

And yes, the grn/yel is safety gnd.


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## jbolt (Apr 22, 2015)

Tony Wells said:


> AC power supplies are not polarized. There is no positive and negative in the conventional sense. If your PS is AC, doesn't matter which one you connect. I gather you are switching the line side of the PS?
> 
> And yes, the grn/yel is safety gnd.



Yes it is AC. The power supply came with the machine and also powers the contractor coils, 220vac in / 24vac out. I reused the contractors in the CNC conversion. My thought is to switch the line off of the power supply? The switch is a relay on the breakout board.

Here is the power supply. Terminals 30, 31 and E are the 24vac side. 30 & 31 go to the contactor coil and E is ground. Across 30 & 31 measures 27vac. 30 to E is 7vac, 31 to E is 19vac.


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## Bill C. (Apr 22, 2015)

You are correct about the wiring.  The valve has diodes to protect it.  Not sure why they used two black wires, I like different colors for tracing a circuit.  They sell rolls of colored electrical tape for wire identification as well.

I like using a Volt-Ohm meter to be sure the ground wire is fully grounded.  Can't afford to be messing with AC, even low voltage, without proper wiring.

Good luck with your project.


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## kingmt01 (May 7, 2015)

Usually two of the same color wires means it doesn't mater which way it is wired. If the circuit is polorized it will set its own P/N by the diodes no mater which way it is wired.


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