When selecting a push button switch, customers may need one button to perform multiple control functions. A common question is whether a single push button can have both NO (Normally Open) and NC (Normally Closed) contacts.
The answer is Yes. Many industrial push button switches are designed with both NO and NC contacts in one unit.
What Does NO + NC Mean?
A button with NO + NC contacts means the switch contains:
One Normally Open contact
One Normally Closed contact
This allows one button to control two different circuit functions at the same time.
How Does a NO + NC Push Button Work?
Before pressing the button:
NO contact: Open
NC contact: Closed
After pressing the button:
NO contact: Closed
NC contact: Open
The two contacts change state at the same time.
Why Use Both NO and NC Contacts in One Button?
Having both contact types provides more flexibility in circuit design.
For example:
Control and Feedback
The NO contact can send a control signal, while the NC contact can provide status feedback to the control system.
Example:
NO contact → Start signal
NC contact → Status monitoring
Start and Indicator Control
A single button can be used to:
Start a machine through the NO contact
Change an indicator signal through the NC contact
Safety Applications
In some industrial control systems, using both contacts helps improve monitoring and reliability.
The NC contact can be used for safety circuits, while the NO contact can be used for control signals.
Common Applications of NO + NC Push Buttons
Buttons with both NO and NC contacts are widely used in:
Industrial machinery
Automation equipment
Control cabinets
Motor control systems
Production lines
Test equipment
What Do 1NO+1NC and 2NO+2NC Mean?
Push button switches are often marked by the number of contacts.
1NO+1NC
Means:
One NO contact
One NC contact
This is one of the most common configurations.
2NO+2NC
Means:
Two NO contacts
Two NC contacts
It provides more connection options for complex control circuits.
Can Emergency Stop Buttons Have NO and NC Contacts?
Yes, but emergency stop buttons mainly use NC contacts for safety circuits.
The NC contact ensures that the circuit will be interrupted when the emergency stop is pressed.
Additional NO contacts can be used for:
Signal indication
Alarm output
PLC monitoring
Conclusion
A single push button can have both NO and NC contacts.
The 1NO+1NC configuration is widely used because it allows one button to provide both control and feedback functions.
ONPOW provides push button switches with different contact configurations, including NO, NC, and NO+NC options, to meet various industrial control requirements.
ONPOW - Professional Push Button Switch Manufacturer
