page contents

Glossary

Ballast. An auxiliary piece of equipment required to start and to properly control the flow of current to gas discharge light sources such as fluorescent and high-intensity discharge (HID) lamps.

Base Socket Cap. The socket is the receptacle connected to the electrical supply; the base is the end of the lamp that fits into the socket. There are many types of bases used in lamps, screw bases being the most common for incandescent and HID lamps, while bi-pin bases are common for linear fluorescent lamps.

Beam Angle. The angular dimension of the cone of light from reflectorized lamps (PAR, Halogen types) encompassing the central part of the beam out to the angle where the intensity is 50% of maximum. The beam angle sometimes called “beam spread” is often part of the ordering code for the reflectorized lamps. 

BiaxTM. GE trademark for its biaxial family of high- efficiency and long-life compact fluorescent lamps. DBX (Double Biax), TBX (Triple Biax) and QBX (Quad Biax) refer to the number of U-shaped legs present in the lamp.

Colour Rendering Index (CRI). An international system used to rate a lamp’s ability to render object colours. The higher the CRI (based upon a 0-100 scale) the richer colours generally appear. CRI ratings of various lamps may be compared, but a numerical comparison is only valid if the lamps are close in colour temperature. CRI differences among lamps are not usually significant (visible to the eye) unless the difference is more than 3-5 points. Scale; 1A - CRI 90-100 Highest, 1B - CRI 80-89, 2A - CRI 70-79 Lowest.

Dichroic Reflector (or Filter). A reflector (or filter) that reflects one region of the spectrum while allowing the other region(s) to pass through. A reflector lamp with a dichroic reflector will have a “cool beam” i.e. most of the heat has been removed from the beam by allowing it to pass through the reflector while the light has been reflected.

Discharge Lamp. A lamp where light is emitted from an electrical discharge between two electrodes as opposed to a filament lamp. Examples are Fluorescent lamps and HID (High-Intensity Discharge) lamps like Metal Halide, Mercury and High-Pressure Sodium. All discharge lamps require some kind of current limiting device, e.g. a ballast, to operate them.

Fluorescence. A physical phenomenon whereby an atom of a material absorbs a photon of light and immediately emits a photon of longer wavelength. If there is a significant delay the phenomenon is called phosphorescence rather than fluorescence. It is interesting that “phosphors” used in lamps exhibit “fluorescence,” not “phosphorescence.”

Fluorescent HO. Fluorescent HO and VHO lamps require special ballasts that generate higher currents than standard ballasts and operate the lamps at a higher wattage than standard lamps. These lamps are generally less efficient than the standard product. Metal Halide HO and XHO lamps operate on the same ballasts as standard lamps and at the same wattage but are more efficient and produce higher light output than standard lamps.

Fluorescent Lamp. A high-efficiency lamp utilizing an electric discharge through low-pressure mercury vapour to produce ultraviolet (UV) energy. The UV excites phosphor materials applied as a thin layer on the inside of a glass tube which makes up the structure of the lamp. The phosphors transform the UV to visible light.

Full Spectrum Lighting. A marketing term, typically associated with light sources that are similar to some forms of natural daylight (6000K and above, 90+ CRI), but sometimes more broadly used for lamps that have a smooth and continuous colour spectrum.

High-Intensity Discharge (HID) Lamp. A general term for mercury, metal halide and high-pressure sodium lamps. HID lamps contain compact arc tubes which enclose various gases and metal salts operating at relatively high pressures and temperatures.

Incandescent Lamp. A light source that generates light utilizing a thin filament wire (usually of tungsten) heated to white heat by an electric current passing through it.

Kelvin. A unit of temperature starting from absolute zero, parallel to the Celsius (or Centigrade) scale. 0C is 273K. 2700K - very warm white. 3000K - warm white. 3500K - white. 4000K - cool white. 6000K - daylight

Lumens. A measure of the luminous flux or quantity of light emitted by a source. For example, a dinner candle provides about 12 lumens. A 60-watt Soft White incandescent lamp provides about 840 lumens.

Lux. A unit of illuminance or light falling onto a surface. One lux is equal to one lumen per square meter. Ten lux approximately equals one foot-candle.

PAR Lamp. PAR is an acronym for parabolic aluminized reflector. A PAR lamp, which may utilize either an incandescent filament, a halogen filament tube or a HID arc tube, is a precision pressed- glass reflector lamp. PAR lamps rely on both the internal reflector and prisms in the lens for control of the light beam.

Rated Lamp Life. For most lamp types, rated lamp life is the length of time of a statistically large sample between first use and the point when 50% of the lamps have died. It is possible to define “useful life” of a lamp based on practical considerations involving lumen depreciation and colour shift and also on the need to reduce lamp replacement costs.

GE Lighting state the following in their catalogue 'Where Life or Average Life are stated we refer to the industry standard definition of how many hours of operation 50% of a given installation will exceed'

RoHS (Restriction of Hazardous Substances). The Restriction of Hazardous Substances (RoHS) Directive aims to minimise the environmental impact of waste electrical and electronic equipment by reducing the quantities of four heavy metals and two brominated flame retardants that it may contain.

Starter. An electronic module or device used to assist in starting a discharge lamp, typically by providing a high-voltage surge.

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

Watt MiserTM. A Watt-MiserTM lamp is a term used by GE to indicate a reduced-wattage lamp with performance characteristics (life, light output, etc.) such that it can usually directly replace a higher-wattage product. Watt-MiserTM lamps are available in a wide range of incandescent and fluorescent lamp types.

WEEE (Waste Electrical and Electronic Equipment). The Waste Electrical and Electronic Equipment Directive (WEEE Directive) aims to minimise the impact of electrical and electronic goods on the environment, by increasing re-use and recycling and reducing the amount of WEEE going to landfill. It seeks to achieve this by making producers responsible for financing the collection, treatment, and recovery of waste electrical equipment, and by obliging distributors to allow consumers to return their waste equipment free of charge.