A coating on the reflector that allows some of the infra read (heat) energy created by the lamp to pass through the back of the fitting instead of being reflected forward.

A material (tungsten in the case of filament lamps) that is heated until it gives off visible light. The tungsten slowly evaporates and darkens the inside of the lamp. As the tungsten evaporates the filament becomes thinner and eventually breaks.

A type of incandescent lamp that uses a tungsten filament and a halogen gas inside a small globe. The halogen gas acts to recirculate the evaporated tungsten back to the filament, thus giving a longer life and keeping the inside of the globe clean. Also known as metal halogen.

General Lighting Service. Refers to a standard mains powered incandescent lamp.

A lamp that produces light from an internal electric arc.

The measurement of the total amount of light output from a lamp.

The measurement of the light level falling on a surface (illuminance). Lumens per square metre.

A type of discharge lamp that produces light with a slight blue-green tinge, used as low cost lighting for factories.

A version of the mercury vapour discharge lamp with additional chemical additives that produces a more natural light than standard mercury vapour. Good colour rendering.

A type of discharge lamp used mainly for outdoor applications. Produces a golden hue light. Good lumens per Watt and long life.