The meaning of beacon colors

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Auer Signal is a global leading manufacturer of signaling technology, operational in 70+ countries. The company produces stack lights, visual-, audible-, visual-audible and explosion proof signaling devices.

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What do the different beacon colors mean?

Every color has its own meaning and is associated with specific things or rules. For example, a red traffic light means “Stop”. Yellow, amber and orange beacon lights are often used to bring attention to something, like road constructions or to slow moving vehicles that are carrying dangerous or heavy goods. Amber, yellow and orange have a high radiance and can be perceived very well from a distance. Speaking of road traffic, beacons with the colors red and orange are also used in the dashboards of cars, in order to inform or warn the driver about an issue.

Green on the other hand means that everything is in order. Green beacon lights are mainly associated with safety. These associations also apply for machines.

In visual signaling, choosing the right beacon color entirely depends on the intended application and the message, that one wants to send to the person viewing the signal. Therefore, it is extremely important to choose the color carefully, in order to eliminate the risk of misunderstandings or fatal errors.

Which beacon colors are available?

Auer Signal offers signal lights with the following beacon colors:

  • Red beacon light
  • Yellow beacon light
  • Orange beacon light
  • Green beacon light
  • Blue beacon light
  • White (clear) beacon light

In addition, multicolour beacons from Auer Signal can display different signal colors with only one dome. Depending on the model, these include the colors magenta and turquoise, as is the case with the RMM multicolour beacon.

beacon light colors

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What is the meaning of the signal beacon colors?

The colors of beacon lights signal different states and require action depending on them. All beacon colors and their meaning in relation to the state of a machine are standardised. This has the advantage that the meaning of the colors can be quickly and correctly understood for different machines.

In addition, when choosing the correct beacon color, it should be noted that the light transmission decreases with colored lenses. The light transmission almost does not change with clear domes. The extent to which the light transmission is reduced depends not only on the color of the lens but also on the light source (halogen, xenon or LED). The measured values mentioned are based on measurements with our colored lenses with a 3 mm wall thickness. All lenses, except the red ones, are backlit with white LEDs.

Even though different beacon light colors are used in traffic, on vehicles, in the dashboards of cars and in many more applications, in this article we are going to focus entirely on the meaning of beacon colors that are installed on signaling devices, such as tower lights or signal lights.


A red bacon light is usually associated with an emergency. This is also the case with red beacon lights on signaling devices. It stands for emergency, a dangerous or hazardous condition and requires immediate action. Signal lights with a red beacon light are suitable for signalling system failures, values that lie outside their safe limits (e.g. temperature) or if there is danger from moving or live goods. Immediate action that can be taken includes stopping or switching off motors or machines.

The highest warning level is indicated by a red beacon light. When it lights up, it stands for the highest level of urgency and not for a general warning. Exceptions to this rule are two-color signal systems with only one red and one green warning light.

Reduction of light transmission:

  • Halogen: -70 %
  • Xenon: -87 %
  • LED: -17 %

LED signal beacons with a red lens are backlit with red LEDs. For this reason, the reduction of light transmission is much lower than when using a red lens and white LEDs.


Because of the high radiance of these colors, they are used to bring attention to something. Yellow and amber beacon lights indicate an imminent critical state and require human monitoring – or intervention. Signaling devices with a yellow or an amber beacon light are suitable for indicating overloads or exceeding of standard values if the duration is only permitted for a limited time. The required action steps serve the purpose of preventing the abnormal condition and avoiding resulting side effects. Precautions and warnings of moderate danger are suitable for the signal color yellow.

Just like orange domes, yellow and amber domes are often used for multi-stage traffic light systems.

Reduction of light transmission:

  • Halogen: -70 %
  • Xenon: -87 %
  • LED: -13 %


Like the color yellow, the signal color orange indicates a warning. Orange stands for an imminent critical condition and requires monitoring or human intervention. Typical applications in which orange beacon lights are is the classic traffic light system in signal towers. The colors red-orange-green are often combined in three-stage signal towers. With these three signal colors, three different states of machines or similar applications can be displayed efficiently and quickly.

Due to the slight reduction in the light transmission of orange calottes, this color is particularly suitable for applications where a high long-distance effect is desired.

Reduction of light transmission:

  • Halogen: -28 %
  • Xenon: -46 %
  • LED: -53 %


The signal color green means a normal, perfect condition. No action is required. Typical applications with a green beacon light on a machine show that the machine is ready for operation or is running without malfunction. By lighting up, green signal lamps indicate normal operation of a machine or that a machine part or switchgear can be switched on.

The color green is to be understood as a safety color and should not be used for warnings or safety instructions. Safety instructions already indicate a possible danger and should therefore be signalled in blue.

As with every other color, there are of course different applications for each of them. In the USA, for example, the green beacon lights are commonly used by the Community Emergency Response Teams (CERT).

Reduction of light transmission:

  • Halogen: -85 %
  • Xenon: -55 %
  • LED: -62 %


The signal color blue indicates a state that requires a defined action by the operator. Excluded are the states of the signal colors red, yellow, orange and green. Any other meaning can be assigned to the color blue.

Signaling devices with a blue beacon light are suitable for a multi-stage signal towers, for example. The signal tower PC7 from Auer Signal allows up to seven different modules. In addition to light modules with a red, orange and green beacon light, the blue beacon light can stand for another defined state.

Reduction of light transmission:

  • Halogen: -88 %
  • Xenon: -55 %
  • LED: -90 %


The clear beacon light has no special meaning. In use, the clear dome is used for other conditions when there is doubt about the use of red, yellow, green or blue. Whether or not the illumination of the clear dome requires the supervision or intervention of an employee must be assessed individually for each application.

Under no circumstances should a clear dome be used for push buttons with stop or off functions. The radiance of clear beacon lights is very high, as it does not consume light transmission. Despite the high light transmission, a clear dome is not suitable for attracting attention to warn of danger.

Reduction of light transmission:

  • Halogen: 0%
  • Xenon: 0 %
  • LED: -9 %


The color magenta, or often equated with purple, plays a major role, especially for applications in the USA. There, magenta beacon lights are used as an alternative to red beacon lights, if for example, the color red is assigned to fire hazard. Especially in the oil and gas industry, this signal color represents a particularly dangerous situation.

When a beacon light in the signal color magenta lights up, people should leave their surroundings immediately or actions should be carried out by trained personnel.

Comparison table: Meaning of the signal colors

ColorMeaningActionsApplicationsReduction of light transmission
RedDanger, highest warning levelImmediate action requiredSystem failures, values outside the safe norm, danger from moving or live goodsHalogen: -70 %
Xenon: -87 %
LED: -17 %
AmberWarning, critical condition imminentMonitoring or intervention requiredModerate danger, short-term exceeding of standard valuesHalogen: -28 %
Xenon: -46 %
LED: -53 %
YellowWarning, critical condition imminentMonitoring or intervention requiredModerate danger, short-term exceeding of standard valuesHalogen: -70 %
Xenon: -87 %
LED: -13 %
GreenNormal stateNo action requiredOperation of a machine, device is ready for operationHalogen: -85 %
Xenon: -55 %
LED: -62 %
BlueAny state, except the meaning of red, orange, yellow and greenDefined action requiredSecurity adviceHalogen: -88 %
Xenon: -55 %
LED: -90 %
ClearNeutralMonitorUse when in doubt about using red, yellow, orange, green or blueHalogen: 0 %
Xenon: 0 %
LED: -9 %

Signal towers with different color modules

With signal towers from Auer Signal, several signal colors can be displayed in one signal device. As with a traffic light, different signals can be controlled. With the signal tower PC7 up to 7 different modules can be used. In principle, the module with the highest alarm level is mounted at the top. The importance of the module decreases with descending order. This means that the topmost and most important modules are also particularly easy to recognise from a distance.

In the case of multi-level signal towers in the ECO series, the XIB labeling panel helps to better understand the meaning of the signal colors. Individual texts and notes on the color modules can be attached to the inscription panel next to the signal towers.

The significance of the different signal colors is illustrated using the example of a seven-level signal tower. Beacon of light meaning:

PC7 Signalsäule

Magenta: Warning of imminent, highly explosive danger

Clear: Indicates an error, but is not system relevant; material is approaching the minimum stock quantity

Blue: Safety notice requiring action by an employee

Yellow: Warning of imminent critical condition

Red: Highest alarm level, machine stands still and is defective

Orange: Warning of imminent critical condition; machine shows atypical behavior

Green: Perfect condition; machine runs in normal operation

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Which signal color is suitable for which type of signal light?

Signal lights from Auer Signal are available in different signal colors as:

The beacon colors red and orange are most common in flashing signal lights. In applications with a flashing beacon, the focus is on rapid signaling of danger. For this reason, the beacon colors red and orange are particularly suitable for such applications. However, these colors are also particularly suitable for use with flashing and rotating mirror beacons.

The colors yellow, amber and orange are most frequently found as continuous light in signal lamps or traffic light systems. The color green is also particularly suitable for the continuous light operation of signal and indicator lights.

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