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LED Glossary

Want to refresh your knowledge on all things LED? This post provides a glossary of terms and an overview of LED terminology.

Accent Lighting

Directional lighting used to highlight particular areas or objects. Used in retail displays and galleries or as guides for pathways and corridors.

Alternating Current (AC)

An electrical current which periodically alternates in direction.

Ambient Lighting

Also referred to as general lighting, ambient lighting provides the primary light source in an area. Ambient lighting should provide a comfortable level of lighting throughout the space without too much glare.

Ambient Temperature

Relates to the air temperature in the environment surrounding the product.


A measurement of electric current flowing through a circuit. It is often shortened to ‘amp’.

Bathroom Zone

Suitability for a product to be installed near or in water. This is divided into 4 categories and relates to the IP rating of a product.

  • Zone 0: The interior of a pool, bath tub or shower basin. For showers without a basin, the height of zone 0 is 10cm and its surface extent has the same horizontal extent as zone 1.

  • Zone 1: The three-dimensional space limited by the finished floor level and the horizontal plane corresponding to the highest fixed shower head or water outlet or the horizontal plane lying 2.25m above the finished floor level, whichever is higher and the vertical plane circumscribing the bath tub or shower. For showers without a basin, the limiting vertical plane of zone 1 is at a distance of 1.2m from the centre point of the fixed water outlet on the wall or ceiling.

  • Zone 2: The three-dimensional space limited by the finished floor level and the horizontal plane corresponding to the highest fixed shower head or water outlet or the horizontal plane lying 2.25m above the finished floor level, whichever is higher than the vertical surface at the boundary of zone 1 and the parallel vertical surface at a distance of 60cm from the zone 1 border. For showers without a basin, there is no zone 2 but an increased zone 1 is provided by the horizontal dimension of 1.2m.

  • Outside zones 0, 1 & 2: No specific IP rating.

Colour Tuneable

There are three types of colour tuneable LEDs available; white-tuneable, dim-to-warm and full-colour-tuneable. White-tuneable LEDs allow the colour temperature of a product to be switched between several variations of white light. Dim-to-warm means that a product will move from a cooler white to a warmer white as it is dimmed. Full-colour-tuneable refers to RGB or RGBW products which are also called Colour Change. Colour change products can be set to thousands of different colours on the spectrum.

Correlated Colour Temperature (CCT)

CCT defines the colour appearance of a white LED. The standard unit of CCT is the Kelvin (K), so CCT is described as a ‘temperature’; a warm light is around 2700K, moving to neutral white at around 4000K, and to cool white, at 5000K or more. These tones range from warm-yellow to cool-blue white light, with several options in between.

Colour Rendering Index (CRI)

CRI is a scale from 0 to 100 percent which indicates how accurately a light source can replicate (render) colours compared to natural daylight. CRI is stated as the Rendering Index (Ra). The higher the CRI, the better the colour rendering. LEDs are generally available with a CRI of between 50Ra and 95Ra, with those in the lower end used for outdoor lighting, and those in the higher end used for professional photography. It is generally accepted that a CRI of >70Ra is good, with >80Ra being very good, and >90Ra being used in specialised locations such us retail.

Digital Addressable Lighting Interface (DALI)

DALI is method of digital dimming and an International Standard (IEC 62386) lighting protocol which can help multiple products from different manufactures work together. Several products can be used through one control and individual units can be set to work through one system.

Direct Current (DC)

An electrical current flowing in one direction only.

IK Rating

Indicates the degrees of protection against mechanical impact. Rated from IK00 to IK10 in accordance with IEC 62262:2002 and IEC 60068-2-75:1997.

IP Rating

Ingress Protection (IP) Ratings indicate the degrees of protection against environmental conditions. Rated from IP00 to IP68 it defines the level of sealing effectiveness against intrusion from foreign bodies, both solids and liquids, in an electrical enclosure in accordance with IEC 60598-1:2003. The first number refers to solids protection and the second number refers to liquids protection.

Kelvin (K)

Kelvin is the scientific unit for measuring CCT (Correlated Colour Temperature) and is used to describe the colour of light output. The higher the Kelvin value of the light source, the closer the colour output will be to sunlight. Typically, commercial and residential lighting will be between 2500K to 6500K.

Kilowatt-hour (kWh)

A measure of electrical energy equivalent to a power consumption of one thousand watts for one hour. The total energy in kilowatt hours is equal to the power in kilowatts multiplied by the time in hours. This can be used to calculate the running cost of LEDs and the cost saving that could be made by switching from conventional lighting methods.

Let us calculate your potential savings and payback period. Simply fill out our short form here and we will do all of the calculations for you.

LED (Light Emitting Diode)

A semiconductor device that emits light through the conversion of electrical energy. LEDs are described as solid-state. The term solid-state lighting distinguishes this lighting technology from others that use heated filaments or gas discharge.

LED Lifetime

Due to the fact that LEDs have no moveable parts or filaments that may break, they can have a very long lifetime. Rather than die instantly as many light sources do, LEDs will have a very gradual drop off of output over time, this is referred to as the lamp lumen maintenance factor, or LLMF. Most LEDs are L70 meaning that after the stated lifetime hours have been reached they will have retained 70% of their original output. LEDs will usually provide 50,000 lifetime hours but many will exceed this.

Lumens (lm)

The quantity of light emitted from a light source. The higher the lumens, the brighter the light output. Also referred to as luminous flux.

Luminous Efficacy (lm/W)

A measure of energy efficiency and is calculated by dividing the lumens by the wattage (lm/W). The higher the lm/W the more energy efficient the product is.

Lux (lx)

A measure of the quantity of light that illuminates a surface, e.g. in a corridor 100 lux are required on the floor and in retail and general office spaces 500 lux should be achieved.

1 LUX = 1 Lumen / m2


A milliamp is one thousandth of an amp (0.001A).

RGB (Red, Green, Blue)

Colour changing products that can be used to add colour to an environment.

RGBW (Red, Green, Blue, White)

Colour changing products that can be used to add colour to an environment. RGBW products can also be run on white when natural lighting is needed.

SELV (Separated Extra Low Voltage)

A low voltage power supply that will not exceed 50V AC or 120V DC.

Task Lighting

An area of increased or specific illumination which enables certain tasks to be carried out.

It is crucial to understand how an area will be used when planning and designing lighting installations.

Thermal Management

LEDs are susceptible to heat. Thermal management refers to components such as aluminium heat sinks which are designed to remove heat efficiently to ensure high light output and long lifetime from the LEDs.


UGR stands for Unified Glare Rating. The lower the value, the lower the glare from a product and the more comfortable the environment. It is important for lighting designers to use products with a suitable UGR for the environment they are designing for, for example, UGR <19 is required for reading, writing and PC based work.

Watt (W)

The unit of electrical power stating the amount of electricity consumed by a product.


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