Buttonholes and flags.

To facilitate the work related to the electric controls , several models of pushbuttons were created, each one with a different operating system, in this way it is possible to obtain different ways of working within a single system of electric controls, changing only the way of activation. The NR26 and NR12 standards specified colors so that there was a working pattern where any professional could identify the flow of operation just by observing the colors of the buttons that were connected.

Buttonhole models.

Buttonhole with retention or selector key: Normally it has two or three positions, being on or off, leaving the circuit with practicality to have in just one button the two functions and still occupying less space. In the same way that there are pros, there are also cons, a disadvantage of using this component is that when the power ends and the circuit is in operation it will remain switched in the on position, so when the power returns, the circuit will automatically return, the same the way in which a protection relay acts by switching off the circuit when the fault is removed, the operation of the circuit will be restored and may impair the internal functioning of some protection component in the future or even bring risk to the workers involved in the system controlled by this type of device.

Selector switch.

Pushbutton or non-retention button:  Widely used in the control circuit together with a seal contact, if not used together with a seal contact, its operation will be temporary. This buttonhole model is widely used for the security it provides when there is a power outage because even with a seal contact, its circuit is turned off and its rewiring is possible only if the button is pressed again, the disadvantage of this model is the need for another button to turn off the circuit, which ends up taking up additional space.


Conjugated on/off button: This model has the necessary functions in the circuit in just one button. Its way of working is the pulsator without retention, being also necessary the use of a seal contact so that the circuit remains connected, however different from the model above, this one has both activations in the same button where the contacts are divided, one side having the button turns on in green and on the other side of the partition with the button turns off in red.

Power button.

Mushroom button or emergency button: Used to switch off the control in case of any abnormality or for maintenance to be carried out where it is necessary to switch it off. This button has retention when pressed by pressing on its structure. To return to its normal state, it is necessary to turn the knob in order to promote unlocking, this maneuver makes the device very safe, avoiding inadvertent maneuvers. Usually, its protective contacts are NC (Normally Closed) used to disconnect the circuit and NO (Normally Open) to signal the emergency condition.

Emergency buttonhole.

Colors for signaling on buttons.

  • Green: Start, start and start.
  • Black: Start, start and start.
  • Red: Stop, turn off, emergency button.
  • Yellow: Reverse the direction, cancel the operation, cancel the dangerous condition.
  • Blue: Any function other than the previous ones.
  • White: Any function other than the previous ones.

In addition to the buttons, there are also signals in the electrical controls to identify what operation is happening on the panel, standardized by NR26 and NR12 for greater safety, standardized in Green, Red, Yellow, Blue and Colorless, but the use of colors must be done as little as possible so as not to confuse the professional who is transiting where the equipment is located or even handling it.

Colors for signaling lamps.

  • Green: Machine ready to operate, circuits and devices in working condition.
  • Red: Alert and danger status, abnormal machine, stopped by a protective device or emergency.
  • Yellow: Value close to the maximum for quantities such as temperature or current, visual fault alarm.
  • Colorless: Machine in normal operation, circuit under-voltage and ready to work.
  • Blue: Any function other than the previous ones.


Now when they are going to develop a project or assemble a remote control panel, they will have the necessary information about which colors to use in the buttonholes and signs, as well as the variety of types and dimensions of the buttonholes available to be used in the electric drives.