Whenever an inherently safe design measure does not make it possible to remove hazards or to sufficiently reduce the risk, then safeguarding and complementary protective measures are utilised. One of these complementary protective measures commonly used is the ‘Emergency Stop’.

Based on Australian and International standards, the emergency stop function shall not be applied as a substitute for safeguarding measures but should be designed for use as a complementary protective measure. It also shall not impair or influence the effectiveness of other protective measures. The emergency stop device should be designed to be easily accessible and actuated by the operator. The types of actuators that may be used include mushroom-type pushbuttons, wires, ropes, bars, or handles.

The emergency stop falls into one of the following stop categories.

Stop category 0

Stopping by means of immediate removal of power to the machine actuator(s).

Stop category 1

A controlled stop with power to the machine actuator(s) available to achieve the stop and then removal of power when the stop is achieved.

 When installing, it should be located at each operator control station, which may include other areas determined by the risk assessment. A risk assessment also dictates the type of the actuator, the category of stop, and the location of the emergency stop. This emergency stop function needs to be available and operational at all times and be able to override all other functions in all operating modes of the machine.

Once an emergency stop device is actuated, the stop command for all the functions shall be sustained until it is reset. This reset is only possible at the location where the emergency stop command has been initiated.

Universally recognised, emergency stop actuators are coloured RED, with YELLOW used as the background colour behind the actuator for clarity.