How to Wire a Push Button Switch: A Step-by-Step Guide

Push button switches are simple parts, but wiring mistakes are common. Many “dead” switches are not defective at all. The wiring is just wrong. This happens most often with switches that have NO, NC, COM, and extra pins for an LED indicator.

This guide explains how to wire a push button switch in a practical way. It covers NO vs NC, what COM does, how a 5-pin LED push button switch is typically arranged, and the most common wiring scenarios. If you are a DIY builder, installer, or entry-level buyer, this is the wiring logic you can reuse across many projects.

Before You Start: What You Need

You can wire most push button switches with basic tools. A small screwdriver, wire stripper, and a multimeter are enough for most jobs. A multimeter is especially useful because it confirms which terminals connect in each state. Switch pin layouts vary by brand, so testing is often faster than guessing.

If your switch includes an LED, check the LED voltage rating (for example 12V or 24V). Some LED rings are built for a specific voltage. Others require a resistor. The datasheet or product listing usually states this.

Understanding Switch Terminals

A push button switch is basically a controlled bridge between terminals. The labels tell you how the bridge behaves when the button is at rest.

COM (Common)

COM means common. It is the shared contact that connects to either NO or NC depending on the button state. Many wiring diagrams start by placing the power source on COM, then routing the output through NO or NC.

You can think of COM as the “moving door” that can touch one of two “door frames.”

NO (Normally Open)

NO means normally open. When the button is not pressed, the circuit is open and no current flows. When you press the button, the circuit closes and current can flow.

NO is commonly used when you want an action to happen only when the button is pressed. It is also common in control circuits and input signals.

NC (Normally Closed)

NC means normally closed. When the button is not pressed, the circuit is closed and current can flow. When you press the button, the circuit opens and current stops.

NC is often used when you want a “default on” behavior, or when the system should detect a break in the circuit.

NO vs NC: A Quick Mental Model

If you remember one thing, use this:

• NO: off at rest, on when pressed
• NC: on at rest, off when pressed

A simple analogy is a hallway light with a door sensor. Depending on how you want it to behave, you choose a contact that either closes or opens when the trigger is activated.

 Step-by-Step: Wiring a Basic Push Button Switch (3-Pin)

Most standard push button switches use three terminals: COM, NO, and NC. In many projects, you will only use two of them.

Basic “Press to Turn On” Wiring (Most Common)

In this setup, the device turns on only when you press the button (momentary behavior) or turns on/off depending on switch type (latching behavior). The contact choice is the same.

1. Connect the power source (or signal source) to COM.
2. Connect NO to the device input (the load).
3. Complete the circuit by connecting the load return to ground/neutral, depending on DC/AC.

When you press the button, COM connects to NO, and the device receives power or signal.

This wiring is also the most common answer to searches like “how to wire push button switch NO NC COM explained.”

“Press to Turn Off” Wiring (Using NC)

If you want the device to be on by default and turn off when pressed:

4. Connect the power source to COM.
5. Connect NC to the device input.

Now COM and NC are connected at rest. Pressing the button breaks that connection.

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Wiring a Push Button Switch With LED (Typical 5-Pin)

LED push button switches often have five pins:

• COM
• NO
• NC
• LED +
• LED –

The switch contacts (COM/NO/NC) control the device. The LED pins power the indicator. These two circuits are separate. That is why the LED can be wired to behave differently from the switch.

This is where many wiring mistakes happen. People assume the LED is internally tied to the switch contacts. On many models, it is not.

Common LED Wiring Scenarios

Scenario A: LED Turns On Only When the Button Activates the Load

This is the “follow the output” setup. The LED lights when the device is powered.

A common method:

• Wire COM → power
• Wire NO → load
• Wire LED + to the switched output (same point as the load input)
• Wire LED – to ground/neutral (depending on DC/AC)

Result: when you press the button and the load receives power, the LED receives power too.

This wiring is popular because the indicator reflects the actual output state, not just incoming power.

Scenario B: LED Always On (Status Indicator)

This is the “panel status” setup. The LED shows the panel has power, even if the button is not pressed.

Typical approach:

• Wire LED + directly to the power source
• Wire LED – to ground/neutral
• Wire the switch contacts (COM/NO/NC) separately to control the load

Result: the LED remains on whenever the supply is present.

This is common in dashboards and control panels where the LED acts like a power presence indicator.

Common Mistakes

“The LED Is Always On, Even When I Don’t Press the Button”

This usually means the LED pins are wired directly to power. If you want the LED to follow the switched output, move LED+ to the output side (often NO path), not the input side.

Exceeding LED Voltage

Some LED rings are designed for specific voltages (12V, 24V). Feeding a higher voltage can overheat the LED or damage internal components. If the LED rating is not clear, check the product datasheet or test with a current-limited supply.

Shorting COM to Both NO and NC

If COM is accidentally bridged to both NO and NC, the switch can create unexpected paths or short circuits depending on the wiring. Many symptoms look like “the load is always on” or “the fuse blows immediately.”

Assuming Pin Layouts Are Universal

Two switches can both be called “5-pin LED push button,” but their pin arrangement may differ. A quick continuity test with a multimeter avoids this issue.

Quick Multimeter Method to Confirm Terminals

If the labels are missing or unclear:

1. Set the multimeter to continuity mode.
2. Test which pin pairs connect at rest. That pair is COM–NC.
3. Press the button and test again. The connecting pair becomes COM–NO.
4. The remaining two pins (that never show continuity with COM) are usually LED + and LED –.

This method works for most standard push button designs.

Wrap-Up

Wiring a push button switch becomes straightforward once you separate two concepts: switch contacts (COM/NO/NC) and indicator power (LED+/LED–). NO and NC determine what happens at rest and during actuation. The LED pins determine whether the light follows the load or stays on as a status indicator.