A Push Button Switch Wiring Diagram helps engineers, electricians, and equipment manufacturers understand how to connect a push button to a control circuit. However, the correct wiring method depends on the switch’s terminal arrangement, contact configuration, and whether the product includes an indicator light.
A 2-pin push button may provide a simple switching function, while a 3-pin or 4-pin model may support different contact arrangements or illuminated operation. The number of terminals alone does not guarantee a specific wiring layout.
In this guide, we explain common push button switch wiring configurations, the differences between normally open (NO) and normally closed (NC) contacts, and the key points to check before installing a switch in an industrial control panel.
Before following a Push Button Switch Wiring Diagram, identify the function of each terminal.
The most common contact configurations include:
A momentary push button normally returns to its original contact state after release. A latching push button maintains its changed state until another operation resets it.
Always check the manufacturer’s terminal diagram before connecting wires. Similar-looking switches may use different internal contact arrangements.
A basic 2-pin push button switch has two electrical terminals. In a typical non-illuminated model, these terminals form a single switching contact.
For a normally open momentary switch, the circuit is open before the button is pressed. Pressing the button closes the contact and allows current to flow through the connected circuit. Releasing the button opens the circuit again.
Power Supply (+)
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[ NO Contact ]
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Load / Input
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Power Supply (-)This simplified diagram illustrates a series connection. The actual supply, load, and return connections must follow the requirements of the equipment being controlled.
Common applications include:
A 2-pin switch may instead use a normally closed contact. In that case, its behavior is reversed. Verify the contact type before connecting it.
A 3-pin push button may use a common terminal with NO and NC contacts, or it may have a different configuration depending on the product design.
For a changeover contact arrangement, the three terminals are commonly identified as:
In the normal state, COM is connected to NC. When the button is actuated, COM changes to NO.
NO
o
/
COM o-------/
\
o
NCThis is a conceptual illustration of a changeover contact, not a universal physical pin layout.
A 3-pin illuminated push button may use a different arrangement. Some products use two terminals for the switching contact and another connection for the indicator, while others have a different internal design.
Do not assume that every 3-pin push button has COM, NO, and NC terminals. Check the product’s wiring diagram or datasheet first.
A 4-pin push button may provide two independent switching terminals pairs, an illuminated contact arrangement, or another manufacturer-specific configuration.
For example, an illuminated push button may separate the switch contacts from the LED supply connections. However, the exact arrangement varies by model.
Before wiring a 4-pin switch, determine:
Switch Circuit Indicator Circuit
Terminal A o LED (+) o
Contact
Terminal B o LED (-) oThis diagram represents one possible arrangement only. It does not identify the actual pin positions of every 4-pin switch.
Never connect a power supply to unidentified terminals based solely on their physical position. Doing so may damage the indicator, switch, or connected equipment.
The wiring arrangement also depends on the operating mechanism.
| Feature | Momentary Push Button | Latching Push Button |
|---|---|---|
| State after release | Returns to normal | Remains in the changed state |
| Typical use | Start, reset, jog | Maintained ON/OFF control |
| Contact behavior | Changes while actuated | Changes and remains switched |
| Selection priority | Temporary command | Maintained command |
A momentary push button is commonly used to send a temporary command to a relay, contactor, or PLC input.
A latching push button is useful when a maintained switching state is required. However, a maintained contact does not automatically provide all the control logic needed for a motor or other machine.
For example, motor control circuits may require overload protection, interlocking, and a suitable stop function. A push button should not replace the required protective devices.
Push buttons are frequently used as input devices in industrial control systems.
A momentary push button can be connected to a suitable relay control circuit to initiate an operation. The relay coil voltage, contact ratings, and circuit arrangement must match the application.
For maintained operation, the circuit may require a latching relay or a separate holding circuit. The correct arrangement depends on the intended control logic.
A push button can provide a digital input signal to a programmable logic controller.
In a typical arrangement, the switch contact connects a compatible input to the required reference potential. The exact wiring depends on whether the input is designed for sourcing or sinking signals and on the PLC’s electrical specifications.
Before installation, check:
Do not assume that all PLC inputs use the same wiring method.
Connecting to the wrong contact can reverse the intended switching behavior. Verify the normal contact state using the datasheet or an appropriate continuity test with the circuit disconnected.
A 3-pin or 4-pin switch does not have a universal terminal layout. Different manufacturers may use different arrangements.
An illuminated push button may require a specific AC or DC supply. Applying an incorrect voltage or polarity can damage the indicator.
The contact rating must be suitable for the connected load. For inductive loads or high-power equipment, a properly rated relay or contactor may be necessary.
Disconnect the power supply before installation or continuity testing. Confirm that the circuit is de-energized and follow the equipment manufacturer’s safety procedures. Work on hazardous-voltage circuits should be performed by qualified personnel.
Selecting a suitable push button requires more than checking its terminal count.
Consider the following factors:
| Selection Factor | What to Confirm |
|---|---|
| Operating mechanism | Momentary or latching |
| Contact type | NO, NC, or changeover |
| Terminal arrangement | Verify the product diagram |
| Electrical rating | Voltage and current |
| Indicator | LED voltage and polarity |
| Mounting size | Panel cutout and body depth |
| Environment | Required IP rating and materials |
For compact industrial control panels, Wuce offers metal push button options with different mounting sizes and designs.
The Push Button Metal Switch is a 12mm metal momentary push button. It may be worth considering for compact control applications, subject to confirming the required contact configuration and electrical specifications.
For applications where environmental protection is important, the Metal Button Waterproof is another option to review. Confirm the exact model’s contact arrangement and protection rating before selecting it for a particular installation.
You can also browse Wuce’s Push Button Switches category to compare available product designs.
Check the terminal markings, product datasheet, or manufacturer’s wiring diagram. If necessary, use a suitable continuity tester with the switch disconnected from all power sources.
An NO contact is open in its normal state and closes when actuated. An NC contact is closed in its normal state and opens when actuated.
A push button’s contacts may not be rated for direct motor switching. Industrial motors typically require an appropriate motor starter, contactor, overload protection, and control circuit.
Additional terminals may supply the indicator independently of the switching contact. The actual arrangement depends on the product design.
No. Four terminals can represent different electrical arrangements. Always verify the terminal functions and electrical ratings of the exact model.
A Push Button Switch Wiring Diagram is useful for identifying contact arrangements and planning connections, but the correct wiring method depends on the specific switch design.
Before installation, confirm the terminal functions, NO or NC contact behavior, electrical ratings, indicator requirements, and intended control circuit. For industrial applications, also ensure that suitable protection and control devices are included.
If you are selecting a push button for a control panel or equipment project, review Wuce’s product specifications and confirm the terminal arrangement before ordering. This helps ensure that the selected switch matches the electrical and installation requirements.
