Technical Glossary

General Information Technical Glossary

Please see the glossary of terms in the table below. You can use the 'Search' feature to refine your term search and find what you're looking for quicker.

Term Description
AC (~) Alternating Current, as found in the mains power supply.
Ampere (Amp) The unit for measuring rate of electrical current: Current (Amps) = Power (Watts) / voltage (Volts).
Ballast A device that limits the amount of current in an electrical circuit.
Beam Angle The degree of width that light emits from a lightsource. It refers to the angle between the opposing points on the beam axis where the intensity drops to 50%. There are many descriptions for the beam angle from narrow spot to wide flood.
Current The flow of electrons. Measured (in amps) as the number of particles passing a given point per unit of time. Current can be induced by application of an electric field through a conductor or by changing the electric field across a capacitor.
COB Abbreviation for Chip on Board. Chip on Board technology groups LEDs together in clusters straight onto the circuit boards. The benefits of COB LED’s are the extremely bright light output, long lamp life, high Lumen output and a greater level of efficiency.
Colour Rendering Index (CRI) - The quality of light A measure of the ability of a light source to reproduce the colours of a reference light. CRI is rated on a scale from 1-100. The lower the CRI rating, the less accurately colours will be reproduced. A light source with a CRI = 100 (Ra) would be a perfect reproduction.
Colour Temperature Can simply be described as the colour characteristics of a light source. Colour temperature is measured in degrees Kelvin. A low colour temperature produces a warm yellowish light and a high colour temperature gives a cold blue light. Usually ranging from warm (yellowish) to daylight (very blue).
DALI Abbreviation for Digital Addressable Lighting Interface, where each driver and control component such as a sensor or switch has a unique address on the lighting installation. This allows for configuration of the lighting installation and flexibility in the future.
Diffuser Optical element used to mix light ray to improve uniformity of light.
Dimming Many Lummineux luminaires are available as a dimmable version. Generally this requires a different driver to the standard fixed output driver and also may require additional wiring on site to operate/control the dimming function.
Driver The driver is often the critical component in a LED luminaire or lamp, more so than the LED chip itself. The driver has to be matched to the power requirements of the LED chip and also have quality components. Drivers that use inferior components such as capacitors will fail before the rated life of the LED chip, reducing the claimed life by as much as 50%.
Efficacy Used to describe the efficiency of a lamp and is measured in lumens per watt (Lm/W). To determine the efficacy of a lamp you divide the lumen output of the lamp by the watts consumed.
Emergency Lighting Facilitates the safe evacuation of an area in the event of a mains failure. The positioning and number of emergency lighting luminaires is detailed in the British Standard, BS5266. It is vital that emergency lighting is maintained correctly to ensure batteries are conditioned so it operates when required.
Fire Rated A fire rated downlight incorporates materials that will expand when heated above a certain temperature to block any gaps and maintain the ability to keep a fire from spreading to other areas of the structure. The fire rating is only approved after the product has been tested and shown to withstand exposure to fire within certain time limits.
Flood Light A lamp that provides a broad beam intended to light a general area.
Frequency Is the rate that the power supply wavelength fluctuates and is measured in Hertz.
Inrush Current Components such as drivers can have high inrush currents for milliseconds due to the use of capacitors, this should be considered when specifying switching and breaker ratings.
Kelvin The SI unit used to measure and denote colour temperature, degrees Kelvin.
KWh Kilo-Watt-hour is the typical billing unit for electricity costs and represents 1kW of power over a 1 hour duration.
LED Abbreviation for Light Emitting Diode. An electronic semiconductor device that emits light when electricity is passed through it.
Light Engine LED light engine or LLE is the combination of one or more LED modules, together with an LED driver meaning it is ready to be fixed in the luminaire.
LM-80 In order to facilitate a comparison of the long term performance between different LEDs, the LED industry developed a standard, IES LM-80-08, which specifies how LED manufacturers and lighting manufacturers can test LED components to determine their performance over time. The LM-80 standard calls for operating a set of LED devices for a minimum of 6,000 hours under well controlled operating conditions (e.g. a constant DC drive current in a thermal chamber where the LED temperature and surrounding air temperature are controlled within specified limits). The LED samples are regularly removed (e.g. every 1,000 hours) from the thermal chamber in order to test relevant electrical and optical parameters for each LED, including forward voltage, light output, and colour point. Once the test reaches at least 6,000 hours, all test data is summarised in a comprehensive LM-80 test report.
TM-21 For many applications it is important to estimate when the light output will drop below 70% of the initial light output. However, given their excellent long-term performance, white LEDs typically exhibit only a small drop in light output after 6,000 hours. Therefore, the LED industry adopted a method, described in IES TM-21-11, to fit an exponential lumen maintenance model to actual LM-80 data. This model can then be used to
LM-70 Lumen maintenance is a prediction of the number of hours and LED will operate before it fades below a useful level of intensity. Currently, lumen maintenance reporting assumes that dropping below 70% of initial lumen output is the end-of-life for the emitter. Hence, L70 predicts when the LED reaches 70% of initial lumen output.
Lumens A lumen is a unit of measurement that is used to show how much illumination a light source provides.
Lumens Per Circuit Watt (LpcW) A calculation of the efficiency of a fitting. Lumens (4000) ÷ Wattage (50W) = 80lpcW.
Lumen Depreciation (L70) - Reduction of light output from the fitting Lumen depreciation reflects the overall performance of a light source through its life. All light sources will encounter lumen depreciation. Factors such as poor thermal management or over voltage may accelerate lumen depreciation. Light levels can be defined as L90, L80 or L70. This is the point at which the Lumen output has depreciated to 90%, 80% or 70% of its original lumens.
Luminous Flux The overall light output of a lamp or luminaire measured in lumens.
Lux A measure of the intensity of light is measured by luminous flux per unit area. One lux is equal to one lumen per square metre.
Maintained Emergency A maintained emergency luminaire is able to be used for both general and emergency lighting. A second live cable allows it to be turned on/off as required and detect a mains power circuit failure.
Microwave Sensor The sensor emits low power microwaves that form a pattern in the area covered. When movement is detected the sensor turns the light source on. Microwave sensors are only recommended for indoor use as they are sensitive to movement and not heat.
Non-Maintained Emergency A non-maintained emergency luminaire ONLY operates in emergency mode and is not for general lighting.
Photocell A photocell / dusk till dawn sensor detects the level of daylight and adjusts accordingly. It changes the resistance depending on how much light is shining onto the sensor and activates or de-activates the light.
PIR (Passive Infrared) A PIR is a device that is used to detect motion through infrared radiation. When a person walks past the sensor it picks up the change in the sensor field and activates the PIR.
Power Supply Device that supplies electric or energy. Most LED Power Supplies Convert Line Voltage (240V AC) to 12 & 24V DC.
RGB RGB stands for the colours Red, Green and Blue. They are the ‘primary’ light colours which come together to make other colours e.g. ‘White’ light is made up of Red, Green and Blue light. In LED RGB lighting systems, Red Green and Blue LEDs are used together to produce many possible colours and provide unique lighting effects.
Self-Contained The most common type of Emergency lighting luminaire, where all of the components are within one Emergency luminaire. This can include gear boxes connected directly to individual luminaires but outside the main luminaire housing. If within 1m, it is classed as self-contained.
SMD Abbreviation for Surface Mount Device. SMDs are very small LEDs which are attached to a circuit board. Surface Mounted Device can be grouped together to achieve a higher level of brightness than standard LEDs.
Wattage The power consumed by the LED.
IP Rating The International Protection Rating / Ingress Protection Rating consists of the letters IP followed by two digits and an optional letter as defined in the international standard EN65029. The IP rating classifies the degrees of protection against dust, moisture and intrusion of solid objects. The IP number is split, the first digit represents protection against dust particles and the second digit represents the protection against moisture.
IP Rating

The table below shows the digits that conform with IP Rating.

First Numeral Numeral Short Description – Example IP6X Second Numeral Numeral Short Description – Example IP5X
0 Non-protected 0 Non-protected
1 Protected against solid objects greater than 50mm 1 Protected against dripping water
2 Protected against solid objects greater than 12mm 2 Protected against dripping water when tilted up to 15º
3 Protected against solid objects greater than 2.5mm 3 Protected against spraying water
4 Protected against solid objects greater than 1.0mm 4 Protected against splashing water
5 Dust-protected 5 Protected against water jets
6 Dust–tight 6 Protected against heavy seas
—— —— 7 Protected against the effects of immersion
—— —— 8 Protected against submersion
IK Rating

The IK rating indicates the level of protection provided by enclosures against external mechanical impact, defined by standard IEC 62262 and IEC 60068-2-75:1997. IK ratings are identified by a code that consists of the letters IK followed by two digits. The two digits range from 00 to 10 and relate to how well the enclosure resists the impact of energy levels measured in joules.

IK Protection Equivalent
IK00 Not protected ——
IK01 Protected against 0.14 joules impact. Equivalent to impact of 0.25kg mass dropped from 56mm above impacted surface.
IK02 Protected against 0.2 joules impact. Equivalent to impact of 0.25kg mass dropped from 80mm above impacted surface.
IK03 Protected against 0.35 joules impact. Equivalent to impact of 0.25kg mass dropped from 140mm above impacted surface.
IK04 Protected against 0.5 joules impact. Equivalent to impact of 0.25kg mass dropped from 200mm above impacted surface.
IK05 Protected against 0.7 joules impact. Equivalent to impact of 0.25kg mass dropped from 280mm above impacted surface.
IK06 Protected against 1 joules impact. Equivalent to impact of 0.25kg mass dropped from 400mm above impacted surface.
IK07 Protected against 2 joules impact. Equivalent to impact of 0.5kg mass dropped from 400mm above impacted surface.
IK08 Protected against 5 joules impact. Equivalent to impact of 1.7kg mass dropped from 300mm above impacted surface.
IK09 Protected against 10 joules impact. Equivalent to impact of 5kg mass dropped from 200mm above impacted surface.
IK10 Protected against 20 joules impact. Equivalent to impact of 5kg mass dropped from 400mm above impacted surface.