Easy Solenoid Valve Wiring Tutorial-How to Connect Switch and Power?

U.S. Solid solenoid valves are vital electro-mechanical devices that control the flow of fluids or gases using an electromagnetic coil. Their operation is both simple and precise: when energized, the coil creates a magnetic field that moves a plunger to quickly open or close the valve. Many people feel confused when wiring a solenoid valve: How to connect the positive and negative terminals correctly? What to do if you want to add a switch for on-off control? We’ll break down the solenoid valve wiring logic step by step, based on U.S. Solid’s official guide. Whether you’re doing a basic direct connection or an advanced setup with a switch, you can get it right by following these steps!

1. Basic Setup: Directly Connect the Solenoid Valve to a Power Source

If you only need the basic function of “open when energized, close when power is disconnected,” wiring is super simple—just 3 steps:

1. Turn off power first for safety: Always disconnect the power switch before wiring to avoid electric shock. This is the top priority for all electrical operations.
2. Connect wires to positive and negative terminals: A solenoid valve usually has two lead wires (you can connect them arbitrarily if there’s no positive/negative marking). Attach one wire to the positive terminal of the power source and the other wire to the negative terminal.
3. Test the effect after power-on: Once connected, turn on the power—the solenoid valve will open immediately and stay open. It will only close when the power is disconnected. No extra accessories are needed for this setup, which is perfect for simple on-off scenarios.

2. Advanced Setup: Control the Solenoid Valve with a SPST Switch

If you want to manually control the solenoid valve (e.g., for timed on-off or manual intervention), adding a SPST (Single-Pole Single-Throw) switch will do the trick. Here’s how:

Step 1: Understand the switch pin functions

A typical SPST switch has 3 pins. Two are “functional pins” (for controlling circuit on-off), and one is the “indicator light pin” (optional, for showing the switch status).

Step 2: Connect the circuit step by step

1. Link one functional pin of the switch to one end of the solenoid valve.
2. Connect the positive terminal of the power source to the other functional pin of the SPST switch.
3. Attach the other end of the solenoid valve directly to the negative terminal of the power source.

Step 3: (Optional) Add an indicator light

If you need an indicator light, connect the switch’s “indicator light pin” to the power source’s negative terminal (sharing the negative terminal with the solenoid valve). This way, when you turn on the switch, the indicator light will turn on simultaneously, letting you visually confirm if the circuit is energized.

Step 4: Test the control effect

Flip the switch on, and the solenoid valve will energize and stay open. Flip it off, the circuit will lose power, and the solenoid valve will close. The control logic is clear and the operation is flexible.

3. Practical Tips