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Emergency Stop Switches

An emergency stop switch is a switch which is attached to a machine to interrupt operation in the event of an emergency.


Standards for the Emergency Stop Function: ISO 13850 and IEC 60204-1


The most relevant standards for emergency stop applications are ISO 13850 and IEC 60204-1. ISO 13850 contains functional aspects and principles for design. IEC 60204-1 is about the safety of machinery and electrical equipment of machines.


Emergency Stop Devices


(1) Types

The following are typical types of emergency stop devices:


  • A pushbutton operated switch
  • A pull-cord operated switch


    • (2) Requirements

  • Electric contacts must have a direct opening mechanism.
  • Emergency stop devices must have a holding function that will mechanically hold in the stop position until the device is manually reset.
  • Actuators of an emergency stop device must be colored red and of a mushroom shape. The background immediately behind the actuator must be colored yellow.
  • Consideration must be given to the following items when a wire is used as an actuator.


    • 1. The amount of deflection needed to generate the emergency stop signal
    2. The maximum deflection possible
    3. The minimum clearance between the wire and the nearest machine in the vicinity
    4. The amount of force required for operation
    5. The ease with which an operator can locate the device, by use of a marker flag or other method
    6. The automatic generation of an emergency stop signal in the event that the wire breaks or becomes detached