31st March 2021

A Guide to Indicator Terminology

A Guide to Indicator Terminology

Introduction to Indicators

In this blog, we are going to examine the different terminology that can be used when looking at indicator lights. This will hopefully give you the language relevant to ensure you purchase the correct indictor for your needs, however, our sales team is also on hand if you have any specific requirements or questions.


What is an indicator?

Indicator lights are visual aids that are used to relay information to a user or operator of a device. These can be large stacks of lights made up of different colours which emit a constant or flashing light to indicate if a machine is operating or if there is a fault. Alternatively, they can be smaller LED indicators designed to show when a certain function is activated or multiple indicators can be used to relay more in-depth information. The majority of indicators are now becoming LED (light-emitting diode) based as this allows for more efficient lighting to be used while also reducing the footprint of the indicator. To learn more about LEDs you can read our in-depth blog article here.

Glossary of Terms

Alternating Current (AC)

Alternating Current is an electrical current that reverses its direction within a particular frequency and is the type of current most often found in homes and businesses.


Ampere (A)

An Ampere often shortened to Amp is the international standard of measurement of the electromagnetic force between conductors, this is more often referred to as the current. An easier way to visualise this is through the river analogy is that the amperes relate to the volume of water (electrons) been moved. The higher the amperage the larger the volume of water that is moving.



Bi-colour simply means two colours. In relation to LED indicators, this means two different colours will be housed within the same body.



Binning refers to the grouping of LEDs during the production process into groups of the same colour temperature. This means the different LEDs within an LED strip or in multiple indicators will have the same colour consistency.


Candela (cd)

A Candela is a measurement of the amount of light which is emitted by a light source in one particular direction. A more in-depth explanation is that candela is the luminous intensity in a single direction from a light source that emits monochromatic ration at a frequency of 540×1012 hertz and has a radiant intensity of 1/683 watt per square radian.


Colour Rendering Index (CRI)

The Colour Rendering Index is a measurement of how accurate the colour given by a light source is when compared with the same colour in sunlight. The CRI is measured on a scale of 0-100, with 100 being an identical match, and is found mainly on LED indicators and LED strips. A CRI of 80+ is generally accepted as the standard although some LED’s are now capable of CRI’s in excess of 90.


Colour Temperature

The colour temperature of a light source is a way to describe the appearance of the light in terms of its colour. The temperature is measured in degrees Kelvin (K) with midday sunlight being around 5600°K. Higher Kelvin gives off a bluer, cooler light with extremely high Kelvin being ultraviolet. Whereas, lower Kelvin gives off a more yellow or warm light with the lowest numbers becoming red and then infrared light.


Direct Current (DC)

Unlike Alternating Current, Direct Current flows in a single direction and is used to power many smaller appliances. Direct Current also flows easily through semiconductors which is why it is used in LED indicators.


Flat indicators

A flat indicator is a style of LED indicator that has a flat bezel with a flat or domed lens. This style of LED indicator is ideal for areas that are required to be wiped down regularly or products that require a smoother finish.


Ingress Protection (IP)

Ingress protection often shortened to IP is an international standard for how protected a product is against solid objects and moisture. The first number after the IP relates to its solid protection while the second number refers to its liquid protection. To learn more about IP ratings you can read our blog article here.


Industrial Indicator Lights

Industrial indicator lights are generally larger style light units that are specifically designed to work within the industrial sector. These can be single lights or lighting towers which can produce continuous or flashing lights in different colours.


Light Emitting Diode (LED)

A Light Emitting Diode is a semiconductor that converts the electrical energy placed upon it into visible light through the release of photons. Read our blog article to understand more about LEDs and how they work.


Lumens (lm)

A lumen is a measurement of the total brightness of a light source as perceived by the human eye. Lumens, therefore, give you a simpler way to determine the brightness of a light when compared to other methods such as Watts, which were primarily used for incandescent lights. The higher the lumen rating the brighter the light appears.


Luminous efficacy

Luminous efficacy is a measurement of how efficient an LED strip or LED indicator is. This is calculated by dividing the number of lumens the light source emits by the number of Watts it uses.


Milliampere (mA)

A milliampere or milliamp is one-thousandth of an ampere, therefore 1000 milliamperes equals 1 ampere.


Millicandela (mcd)

Millicandela is one-thousandth of a candela, therefore 1000 millicandela equals 1 candela.


Panel Mount

Panel Mount describes how the indicator is mounted. These are designed to be fitted to an external case or enclosure with the wiring terminations on the inside and the LED and bezel on the outside.


Plastic indicators

Plastic indicators are manufactured with fully plastic housings, this makes them lighter and usually slightly cheaper than their metal housing alternatives.


Reflector indicators

Reflector indicators are specially designed with a bezel that can direct the emitted light into a focused point. This means they are generally brighter and therefore ideal for areas with high levels of ambient light.



RGB stands for Red, Green and Blue. RGB LEDs are designed so that all 3 individual LEDs are within a single housing. They are also individually adjustable which allows an RGB LED to produce over 16 million colours.


Solid-state indicator

A solid-state indicator relates to an LED style indicator rather than an incandescent style. This is because an LED does not have any electrical elements which are separate from the main system such as the filaments in incandescent bulbs.


Viewing Angle

The viewing angle of a LED refers to the size of the cone of light that is emitted up to the point where it loses half of its peak illumination level. A viewing angle of 20° for instance will be a much narrower light than one with a viewing angle of 72°.


Voltage (V)

Voltage or Volts is the difference in electric potential between two given points. An easier way to visualise this is the river analogy where the voltage relates to the steepness of the river or the speed of the water (electrons). The higher the voltage the faster the water is moving.



A watt is the standard unit of measurement equivalent to one joule per second. It is more commonly referred to as the power rating of the device or circuit. To calculate the watts of an electrical system you multiply the voltage by the ampere e.g. 240V x 2A = 480 watts.


Waterproof LED indicators

A waterproof LED indictor is usually a submersible or semi-submersible indictor, these usually have an IP rating of IP67 or IP68 and are ideal for applications where the LED indicator will be subjected to environments with high moisture content or the possibility of being submerged.


Indicator lights are visual aids that are used to relay information to a user or operator of a device.

An LED indicator is a type of indicator light that incorporates a light-emitting diode. This results in a highly effective light source that has low power consumption and a long lifespan.

Indicator lights are used to relay information to an operator, these are extremely useful in applications such as industrial & commercial control panels, agricultural equipment, marine & military applications and medical & scientific equipment.

Some LED indicators are available with built-in resistors, these are called ballast resistors and are used to limit the amount of current which flows through the LED. This is a safety feature that is useful in some but not all circumstances to prevent the LED from being destroyed by electrical overload.

A flat indicator is a style of LED indicator that has a flat bezel with a flat or domed lens. This style of LED indicator is ideal for areas that are required to be wiped down regularly or products that require a smoother finish.

An LED strip is a length of surface-mounted LEDs often fitted to a flexible base. This allows the lighting to be designed in different ways including custom lengths and even lighting over or around curves, which would not be possible with conventional lighting such as incandescent bulbs.

An IP rating is an international standard of how protected a product is against solid objects and moisture. Read our blog article to learn more about IP ratings.

While products that are rated IP65 and upwards are suitable for outdoor use, only products rated IP68 and IP69K can be considered fully waterproof as these are submersible in water for prolonged periods of time. IP67 rated products can also be fully submerged in water but these are usually only tested for 30 minutes in water up to 1m in depth.

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