Push button switches represent the most intuitive operational interface on machinery and automation control panels. However, engineers and procurement specialists frequently overlook critical selection factors—such as whether a button requires momentary or latching functionality, Normally Open (NO) versus Normally Closed (NC) contact setups, or how environmental moisture and oil might affect long-term contact conductivity. 

Backed by decades of manufacturing expertise in industrial switches, Auspicious Electrical Engineering breaks down illuminated option selection, ingress protection ratings, and double-circuit wiring strategies to help you specify the most reliable switches quickly.

Table of Contents

1. Key Types and Operating Mechanisms of Push Button Switches

2. Flush vs. Extended vs. Illuminated Push Buttons: Finding the Right Fit

3. Industrial Push Button Switch Quick Reference Table

4. 4-Step Selection, Wiring, and Installation Workflow

5. Frequently Asked Questions (FAQ)

Key Types and Operating Mechanisms of Push Button Switches

Despite their straightforward design, the internal mechanism of a push button dictates its circuit logic:

• Momentary Push Buttons: Conduct electricity when pressed and instantly spring back to their default position upon release (like a doorbell button). Ideal for machine start commands, inching (JOG) operations, or reset signals.

• Latching Push Buttons: Lock into an ON or OFF state when pressed and require a second press to release back to home position. Commonly used for main power toggles or continuous run modes.

• Normally Open (NO) & Normally Closed (NC) Contacts: NO contacts remain open in their resting state and close when actuated (used for starting). NC contacts remain closed in their resting state and open when actuated (used for stopping or power isolation).

Flush vs. Extended vs. Illuminated Push Buttons: Finding the Right Fit

Choosing the right actuator style depends on ergonomics, safety rules, and available panel space:

• Flush Push Buttons: The actuator surface sits flush with the guard ring, preventing accidental shoulder or tool bumps. Ideal for high-safety start functions.

• Extended Push Buttons: The actuator protrudes beyond the bezel, making it easy to hit quickly during frequent cycling or blind-touch operations.

• Illuminated Push Buttons: Features an integrated internal LED light source, providing immediate status illumination upon press and saving valuable control panel real estate.

Industrial Push Button Switch Quick Reference Table

4-Step Selection, Wiring, and Installation Workflow

1. Verify Panel Cutout and Rear Depth: Measure panel hole diameter (standard 22mm or 30mm) and ensure adequate interior depth for stacked contact blocks.

2. Define Actuation Logic & Contact Needs: Decide whether a momentary or latching actuator is required, and select the needed number of NO/NC contact blocks.

3. Assess Environment Protection Ratings: If exposed to water jets, dust, or oil mist, specify IP65 or higher switches fitted with silicone rubber protective boots.

4. Secure Wiring and Test Mechanics: Tighten terminal screws firmly onto wire leads, and perform tactile testing after installation to ensure smooth spring return and proper LED lighting.

Frequently Asked Questions (FAQ)

Q1: What does "1NO1NC" mean on a push button switch specification?

1NO1NC indicates that the switch is equipped with one Normally Open (NO) contact block and one Normally Closed (NC) contact block simultaneously. When you press the button, the NO contact closes while the NC contact opens, allowing you to control two separate circuits at once (e.g., starting a motor while turning off a stop indicator light).

Q2: How do I select the correct LED voltage for an illuminated push button?

The illuminated LED module voltage must match your control circuit power supply. Common standard voltages include DC 24V (widely used in modern automation panels) and AC 110V/220V (standard in traditional distribution boxes). Specifying the wrong voltage can cause illumination failure or burn out the LED block.

Q3: Why does a push button fail to spring back after prolonged use?

This typically happens due to two reasons: first, environmental dust or cutting oils penetrating the actuator slide guide and jamming the spring mechanism; second, over-tightening the mounting bezel nut, which distorts the switch housing slightly. In dusty environments, specify IP67 sealed buttons with protective boots and ensure balanced torque during mounting.