Push Button Switch Classification: NO, NC and Composite Buttons Guide

Distinguish momentary, latching and special style push buttons for different industrial projects

Push button switches can be categorized by contact function and operation structure, which helps engineers select the correct model for panel installation. There are three main contact types: normally open (NO), normally closed (NC) and composite buttons.
Normally open buttons keep circuits disconnected at rest and close only while pressed, mainly used as start and jog control. Normally closed buttons maintain conduction in static status and cut off circuits after pressing. Stop and emergency stop circuits prefer NC contacts for safety. If wires break, the circuit automatically shuts down equipment. Composite buttons contain both NO and NC contacts with a “break before make” sequence, ideal for motor forward and reverse interlock.
By operation styles, common types include standard momentary buttons, red mushroom emergency stop, key lock buttons, rotary selector switches, LED illuminated buttons and waterproof anti-corrosion models. Illuminated buttons show running or fault status through built-in LED. Waterproof sealed switches suit humid and dusty workshops. Different types match diverse operating safety requirements for machine panels.