BASICS 6 of 19

A 2 x 4 Fluorescent Lamp Fixture

A fixture is a housing for the lamp that redirects the light on to surfaces that need to be lit.

Fixtures contain (1) Reflectors (2) Lenses or Louvers and (3) Ballasts.

The Reflector is usually a shiny surface but it could also be plain white paint. Underneath, there is a plastic or glass sheet (Lens) or a grid-like Louver to disperse the light appropriately. The picture shows a "deep-cell parabolic" louver which directs the light downwards and prevents it from spreading--important to reduce glare on computer screens.

The 2 foot by 4 foot (two-by-four) fluorescent downlighting fixture is the workhorse of lighting as far as indoor commercial spaces are concerned (offices, schools, hospitals, etc.)

Fixtures (also called luminaires) typically allow out 60% to 90% of the light emitted by the lamp. Dust collecting on fixture surfaces can absorb light; periodic cleaning of fixtures is strongly recommended.