AC (~)

Alternating Current, as found in the line voltage power supply.

Accent Lighting

Also commonly called display or highlighting. Accent lighting is typically at a higher intensity to emphasise an object or area. A Ratio of 3:1 versus ambient lighting is recommended for accent lighting to be noticeable.

Ambient Lighting

The general background illuminance is usually at a low level and with task and/or accent lighting used for the task or display.

Ambient Temperature

The air temperature surrounding the luminaire or component. LED luminaires are particularly temperature sensitive with excess temperature affecting performance and rated life. See also Junction Temperature.


The unit for measuring rate of flow of electrical current: Current (Amps) = Power (Watts) / Voltage (Volts)

Asymmetric Light Distribution

Where the distribution of light from a luminaire is not even in one plane. Common in display luminaires such as ‘wall washers’ where light is directed intentionally in one direction.


The ‘swivel’ angle, as used in floodlighting or display lighting designs and installations.


Beam Angle

Not, as commonly thought, the width or angle of light emitted from the lamp/luminaire. Instead, the point where intensity reaches 50% of the peak value.


The method used for sorting LED chips during manufacture, typically based on output and color temperature. The latest manufacturing techniques employed by leading chip manufacturers are yielding chips that no longer require binning as the consistency and tolerance is greatly improved.


While brightness is what people see and react to, luminance is the actual surface brightness of an object and is measured in candelas per metre2.


Candela (CD)

The SI unit for luminous intensity.


The LED Chip is the light source.

Chip on Board (COB)

Is the latest generation of LED light source. Many small LED chips are incorporated in one packaged light source to provide a more efficient solution that can be combined with a lens and/or reflector to maximise the light distribution.

Color Appearance

Term used to describe how ‘white’ the emitted light looks. Commonly, warm, neutral, cool and daylight are used to categorise.

Color Rendering Index (CRI)

A measure of the degree of color shift objects undergo when illuminated by the light source as compared with those same objects when illuminated by a reference source of comparable color temperature. The reference source has a CRI of 100. Natural light (daylight) would also be 100.

Correlated Color Temperature (CCT)

The description used to describe the effect of heating an object until it glows incandescently, the emitted radiation, and apparent color, changes proportional to the temperature; easily envisioned when considering hot metal in a forge that glows red, then orange, and then white as the temperature increases. Measured in degrees Kelvin.

Corridor Function

Refers to luminaires that when not required to emit 100% light output, switch to 10% output. This ‘standby mode’ allows the luminaire to provide a low level of illumination for a feeling of security so the area is not totally dark. Upon sensing movement the output automatically and instantly switches to 100%. This is particularly useful in circulation areas such as corridors and stairwells.

Cut Off Angle

Small downlights can appear too intense and very glary, so cut off angle illustrates the point where the light source can’t be seen.

Cut-out Dimension

Size of hole required to install luminaire.



Stands 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 infinite configuration of the lighting installation and flexibility in the future.


Many Luceco luminaires are available as a dimmable version option. 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.

Direct Lighting

Luminous flux that reaches the working plane without being reflected from walls/ceiling or within the luminaire itself.


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 will fail before the rated life of the LED chip, reducing the claimed life by as much as 50%.



Is the measure of how efficient a lamp or luminaire is. This can be expressed as (source) lumens per watt, which is the normal measure for lamps. Or, as luminaire lumens per circuit watt that is common for luminaires. The figure for luminaires will also include the LOR of the luminaire in the calculation.

Escape Route

Emergency lighting along a route such as a corridor or staircase to enable safe evacuation.


Flux/Luminous Flux

Luminous flux is the measure of the perceived power of light, adjusted to reflect the varying sensitivity of the human eye to different wavelengths of light and is expressed in Lumens (lm).


Is the rate that the power supply wavelength fluctuates and is measured in Hertz.


General Lighting

Lighting to illuminate the general area without supplementary task lighting.


Is difficulty seeing in the presence of bright light such as direct or reflected sunlight or artificial light and is proportional to the background illuminance, a good example is a car headlight that provides glare at night time but not during the day.


A photometric device for testing the luminous intensity distribution, efficiency, and luminous flux of luminaires.


Heat Sink

A part of the thermal system that conducts or convects heat away from sensitive components, such as LEDs and electronics.

Hertz (HZ)

The unit to measure frequency.

High Power LED

A high power LED, sometimes referred to as a power LED, is one that is driven at a current of 350mA or higher.

High Risk Area

A requirement in Emergency lighting where a process may require safe shut down or an increased hazard. Higher emergency lighting levels are therefore required local to the risk.



Illuminating Engineering Society, an American organisation that provides standards and recommendations. Photometric data files are common in .ies file format.


The intensity of light falling on a surface area. If the area is measured in square feet, the unit of illuminance is footcandles (fc). If measured in square meters, the unit of illuminance is lux (lx).

Indirect Lighting

Lighting that is reflected by room surfaces or within the luminaire before falling on to the working area. As a result of reflection it is often lower in intensity and glare.

Ingress Protection (IP) Rating

A system that identifies the protection that a lamp or luminaire has against solid objects and water. The first digit being solid object protection and the second one resistance to water. All Luceco products IP20 unless otherwise stated.

Initial Lumens

The output up to 100 hours use.

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.

Integrating Sphere

A device used for a variety of optical, photometric, or radiometric measurements.

Isolux Diagram

A graphical representation of common illuminance levels to show lighting levels over a calculated area.



The point at which the Positive and Negative conductors meet in a LED.

Junction Temperature

A critical consideration in LED lamp or luminaire design. For every 10Adeg;C that the junction temperature exceeds the optimum figure, life of the LED chip is reduced by 50%. Overrunning LEDs by operating at higher amps will cause this to happen.



The SI unit used to measure and denote colour temperature, degrees Kelvin.


Kilo-Watt-hour is the typical billing unit for electricity costs and represents 1kW of power over a 1 hour duration.



A lamp converts electrical power into light and sometimes they are called ‘bulbs’ due to the traditional lamp shape.


Light Emitting Diode. An LED is a solid-state semiconductor device that converts electrical energy directly into light. On its most basic level, the semiconductor is comprised of two regions. The p-region contains positive electrical charges while the n-region contains negative electrical charges. When voltage is applied and current begins to flow, the electrons move across the n-region into the p-region. The process of an electron moving through the p-n junction releases energy. The dispersion of this energy produces photons with visible wavelengths. Most LEDs emit a blue light as that is the most efficient format, a phosphor coating turns the blue light into the white light required.

LED Rated Life

LED chip figures are quoted by the chip manufacturer and in some cases these are not translated when the chip is used in a luminaire where it can run hotter. As heat affects the LED chip, the life can be reduced dramatically.

Light Output Ratio (LOR)

Light Output Ratio is the percentage difference between the luminous flux emitted by the light source and the amount emitted from the fixture it is housed in.


Lumens per circuit watt is total lumens emitted from the source / total lumen wattage including control gear.

Lumen Depreciation

Describes the percentage of light lost relative to the initial lumen output. LEDs depreciate at a far slower rate than other light sources, so a LED with a lower initial output can quickly provide more light than a faster depreciating light source.

Lumen Maintenance

The luminous flux at a given time in the life of the LED. This is expressed as a percentage of the initial luminous flux. This usually determines the rated life of a LED product as the point it should be replaced.

Lumens (lm)

The international (SI) unit of luminous flux. Lumens are the new measure of light output. Watts cannot be a reliable measure due to the different efficacy of light sources and the ongoing improvement in LED efficacy through development.


The surface brightness of an object and measured in candelas/m2.

Luminous Efficiency

The percentage of total lamp lumens that a lighting fixture, luminaire, or system emits, minus any blocked or wasted light.

Lux (LX)

The SI (International) unit of illuminance, or luminous flux incident on a unit area, frequently defined as one lumen per square metre (lm/m2).


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 disturbs the pattern, movement is detected and 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.


Organic Light-Emitting Diodes (OLED)

Organic light-emitting diodes (OLEDs) are based on organic (carbon based) materials. In contrast to LEDs, which are small point sources, OLEDs are made in sheets which provide a diffuse area light source. OLED technology is developing rapidly and is increasingly used in display applications such as mobile phones and PDA screens. However, OLEDs are still some years away from becoming a practical general illumination source.



A coating of phosphorescent material which photons from a royal blue LED pass through causing those photons to exit with a different colour property.

Photometric Data

Is a generic term for light output and distribution data for a lamp or luminaire and can be shown in many formats. Generally data is produced following the IES or ELUMDAT method to provide a .ies or .ldt computer file for use in a lighting design program such as Relux or Dialux. Photometric data is available for a wide selection of Luceco luminaires from our website.


Passive Infra Red sensors detect movement by the change in background temperature as body heat moves into the area.

Power Factor

The active power divided by the apparent power (i.e., product of the rms input voltage and rms input current of a driver).

Power Factor Correction

In an electronic device, such as an LED lighting fixture, a system of inductors, capacitors, or voltage converters to adjust the power factor of electronic devices toward the ideal power factor of 1.0.


Remote LED Driver

Some LED lights in our range use a remote plug and play LED Driver, that offers flexibility to select either a fixed output, dimmable driver or emergency versions, with all being interchangeable.

Remote Phosphor

A phosphor conversion technique in which photons from a royal blue LED pass through a phosphor material that is not attached to the LED chip.


Restriction of Hazardous Substances (2002/95/EC) is an article 95 directive, meaning it is across all European Union member states. Since July 1st 2006 the use of hazardous substances is restricted in products, to prevent environmental harm. The prohibited substances are Lead, Mercury, Cadmium, Hexavalent Chromium, Polybrominated Biphenyls and Polybrominated Diphenyl Ethers. All relevant Luceco products comply.



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.


Surface-mount LEDs.

Source Lumens (lm)

Source or Chip lumens is the output of the LED array and does not allow for any reduction or increase from the luminaire.

Source Wattage

Also could be referred to as chip wattage is for the LED only and does not include any control gear.


Task Lighting

localized lighting intended for a specific task.

Thermal Management

Controlling the operating temperature of the product through design, examples include heat sinks and improved airflow.


Ultraviolet (UV)

Electromagnetic radiation with wavelength shorter than that of visible light. LEDs emit minimal UV and therefore do not attract insects or potentially damage sensitive materials illuminated by them.

Utilization Factor

In lighting design, the proportion of the luminous flux emitted by a light source, which reaches the working plane.



The term used to describe the electrical potential difference between oppositely charged conductors.



The power consumed by the LED.

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