Should Your E-Stop “Be Fail-Safe?”



When it comes to safety, the selection of the right stop control device can make the difference. EAO offers emergency stop switches that provide extra assurance with “Fail Safe” operations for use in critical applications.

E-stopHow does it work…
  • If the E-Stop actuator is mechanically separated from the “Fail Safe” contacts, the equipment is immediately stopped
  • The act of dislodging the switch actuator opens the “Fail Safe” connection, effectively breaking it

Contact separation can often occur from improper installation. Without this “Fail Safe” feature, there is a possibility that the machine shut down will not occur in a critical situation.

Safe emergency stopping
According to international standards, the emergency stop function must be initiated by a single human action using a manually actuated control device. The E-Stop function must be operational at all times and designed to stop the machine without creating additional hazards. Resetting the electrical system can only be done by first releasing the E-Stop that was originally activated. 

E-Stops are critical to the human machine interface (HMI). restart. It should be noted that resetting E-Stops does not in itself restart the machinery; it only permits restarting through normal procedures appropriate for the machinery involved.

Not all stop E-Stops are made the same. Designers need to have a thorough knowledge of E-Stop fundamentals, E-Stop switch characteristics and capabilities, and the international and U.S. standards and compliance requirements.

E-Stops are required on all machinery independent of the type of energy used to control the function, except for machines in which an E-Stop function would not lessen the risk. Equipment designers must also consider a range of other safety functions.


E-Stop catalog | Config info | White paper

HHP Associates, Inc., a division of ESI,  is the Florida representative for EAO Switches, a global technology leader and manufacturer of Human Machine (HMI) systems and components serving the transportation, machinery, heavy duty, lifting and moving, specialty vehicle, medical and automotive markets. Intuitive development skills along with global manufacturing capabilities, worldwide supply chains, and superior project and consultation management result in complete and innovative HMI Systems. HMI components include award-winning pushbuttons, indicators, emergency stop switches, rotary selectors, keylocks and more.