The color of the push button switch actuator should meet the requirements of Electrical safety of machinery-Electrical equipment of machines –Part 1 General requirements (IEC60204-1).
For the start/connect function, the color of the actuator should be white, gray, black or green. White is preferred, but red is not allowed.
For stop/disconnect function, the color of the actuator should be black, gray, or white, and black is preferred. But green is not allowed. Red is also allowed, but it is recommended not to use red when it is close to the emergency button switch.
The preferred color of the button actuator for alternate operation of start/on and stop/off functions is white, gray or black, and red, yellow or green is not allowed.
For the button actuators that cause the equipment to operate when pressed, and stop when released, the preferred color is white, gray or black, and red, yellow or green are not allowed.
The actuator of the reset function button should be blue, white, gray or black. If they are also used as a stop/disconnect function, it is best to use white, gray or black. Black is preferred, but green is not allowed.
The actuator of the emergency stop button should be red, and the surrounding color closest to the actuator should be yellow.
The meaning of the color of the button and application examples are shown in the following table.
Operation in case of danger or emergency
Emergency stop, emergency function start
Operation under abnormal conditions
Intervention to stop the abnormal situation; intervention to restart the interrupted automatic cycle
Operation under normal conditions
Operation when forced action is required