A Normally Open (NO) Push Button is a push button that, in its default state, makes no electrical contact with the circuit. Only when the button is pressed down does it make electrical contact with the circuit. When the button is pressed down, the switch makes electrical contact and the circuit is now closed.
A Normally Closed (NC) Push Button is a push button that, in its default state, is closed to the circuit.Only when the button is pressed does it disconnect from the circuit.
For components such as travel switches and pressure relays. Under the condition of no external force, the contacts in the open state are normally open contacts, and the contacts in the closed state are normally closed contacts.
Understanding the roles of ‘NC’ (Normally Closed) and ‘NO’ (Normally Open) configurations is pivotal when selecting the right push button switch for your application. Whether you’re designing for safety features—such as emergency stop circuits—or control functions in electronic systems, knowing which contact type to use ensures reliable performance and proper circuit operation.This distinction helps you match the switch’s behavior to your needs: for example, use an NC contact for circuits that require a default closed path (like safety interlocks), and an NO contact where the circuit should only close when the button is actively pressed.
The so-called relay coil is not energized, that is, the switch that supplies power to the relay coil is in an open state, the normally open contact of the relay itself is in an open state, and the normally closed contact is in a closed state.
For example：
Why Understanding NO and NC Configurations Matters
Knowing the difference between NO (Normally Open) and NC (Normally Closed) configurations is essential when choosing a push button switch for your application. Selecting the correct type ensures your circuit behaves as expected—vital for both safety and control purposes. For instance, in emergency stop systems, an NC push button is preferred so that the circuit remains complete unless the button is pressed to break the connection. On the other hand, machines that require activation only when a button is pressed often use NO push buttons.
In short, matching the switch type to the function helps prevent wiring mistakes and avoids possible hazards or equipment malfunctions.
How do distinguish between normally open and normally closed contacts in our buttons？
-----La38 series:
This series buttons support combined contact switch, common 2NO-green module as normally open contact, 2NC-red module as normally closed contact, 1NO1NC is a red module and a green module combination contact.
-----Xb2 series:
An upgrade to the original lay5 product on the market, the latch rotary disassembly. Contact is also consistent with la38 button switch base contact distinction. It is also the distinction between red and green modules. Red represents normally closed and green represents normally open.
-----Metal series switch:
Waterproof metal switch plastic button, there will be symbols to distinguish normally open foot and normally closed foot.
As shown in the figure:
NO: Normally open foot
NC: Normally close foot
