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Jargon Busting – What Do LED’s Mean?

Posted on: 23rd Aug 2016

The lighting industry is littered with technical terminology. Illuminate your options with our A to Z explanation of some everyday industry expressions.


Accent lighting is directional lighting, employed to emphasise a particular object or to draw attention to a display.

Ambient lighting is the general lighting in any given area. While it excludes task and accent lighting, it incorporates room lighting and the level of available daylight.

Daylight harvesting is the term employed when an interior lighting design incorporates daylight as a way of reducing energy consumption.

A dimming control is another popular energy conserving device. It is used to lower the light output of a source by reducing its operational wattage. Lamps will state whether they are dimmable and hence, whether the lamp lumens can be varied while maintaining reliability.

There are two types of mains control dimmer. A leading-edge dimmer uses a TRIAC (Triode for Alternating Current) switch to control power. Leading-edge dimmers are the more common option available and while cheaper and simpler than many alternatives, their use can be limited with LED lighting circuits.

A trailing-edge dimmer, however, uses a transistor and offers a more sophisticated alternative, providing a smoother, more silent dimming control.

There are different ways of dimming LED lights. Many LED lamps are designed to be used with a transformer, however, performance can vary and compatibility cannot always be guaranteed. Consequently, a driver is often developed in conjunction with a LED, providing much-improved compatibility.

While mains dimming works well, there are alternatives. 1-10v dimming operates effectively with dedicated LED fittings. Dimming is often smoother and lower than the leading-edge and trailing-edge mains dimming options. This method, however, requires a separate control cable to be run from the controller to the fittings driver.

A sophisticated option, requiring the use of a control cable is digital dimming. DSI (Digital Series Interface) is an enhanced, controllable version of digital dimming. It enables the grouping of luminaires, daylight-linked dimming, and other controllable operations.

Similarly, DALI (Digitally Addressable Lighting Interface) is a sophisticated digital system, used more commonly in commercial environments. It requires a control cable which can be run between many fittings, allowing individual luminaires to be controlled from a central desktop PC.

A floodlight is a luminaire used to light a scene or object to a level much brighter than its surroundings.

Glare is the term used to express the visual discomfort experienced by excessive brightness. Glare is calculated using a precise formula.

UGR (Unified Glare Rating) measures the luminance of a lamp divided by the background of visible luminance from the room. The number calculated is the UGR and the lower, the better. Low levels of UGR will go unnoticed whereas higher levels will definitely cause a distraction.

An IK (Impact Protection) rating measures the degree of protection provided by electrical equipment enclosures against external mechanical impacts. The higher the rating, the greater the protection provided by the enclosure.

Similarly, an IP (Ingress Protection) rating measures degrees of alternative protection. The rating constitutes the characteristic letters IP, followed by two numerals which indicate conformity with stated conditions. The first number indicates the level of protection of persons against contact with live and moving parts and protection of the equipment against ingress of solid foreign bodies. While the second number indicates the level of protection of the equipment against harmful ingress of water. From zero protection to being dust and water tight, the higher the rating, the better protected the light fitting.

A LED (Light Emitting Diode) is a solid that directly converts electrical impulses into light. Modern LEDs incorporate different materials to change the colour characteristics of the emitted light. Different colour temperatures dictate the type of light produced and subsequently, their ideal application.

The lumen and the lux are both units of measurement. A lumen is used to express how much illumination a source of light provides, whereas the lux measures the intensity of light as seen by the human eye. The lux is measured by luminous flux per unit area and one lux is equal to one lumen per square metre.

Modern lighting embraces the concepts of efficacy and efficiency, with the overall aim of providing energy-saving solutions. The LPW (Lumens per Watt) is a measurement of how effective the light source is in converting electrical energy into lumens of visible light.

Similarly, the LOR (Light Output Ratio) is a figure that shows how much light gets lost inside a luminaire.

Maintained lighting is designed to be lit continuously and will continue to work even in the event of a power failure. A type of emergency lighting, maintained lighting allows a unit to act as a standard light fitting while still supplying the necessary backup in the event of a power cut.

Conversely, non-maintained lighting is designed to turn on in the event of a power failure. Linked to the lighting circuit, it reacts to a power cut by ensuring emergency exit routes remain illuminated.

A PIR sensor (Passive Infrared Sensor) radiates wavelengths to detect heat energy in nearby objects. As such, when a PIR sensor is incorporated in lighting, the device is able to capture movement and trigger the light accordingly. PIR sensors are ideal for use in outdoor security lighting.

Task lighting describes the use of supplemental lighting provided to assist in performing a localised task. Table or inspection lamps are obvious examples.

A watt is a unit of electrical power. Lamps are rated in watts to indicate the rate at which they consume energy.

SERA Technologies provide high-quality LED lighting for a range of applications. With a wide range of commercial and domestic lighting solutions to suit any style and space, contact us today to discuss your LED lighting requirements.