Outdoor Lighting Glossary
Come across a lighting word you aren't sure of? Completely new to the world of lighting? We feel your pain! Here you will find a collection of terms and concepts that should help to make your life easier.
Have you come across a term that we don't have? e-mail the Webmaster and we'll add it!
Select the first letter of the word from the list above to jump to appropriate section of the glossary.
R Lamps - Reflectorized lamps available in spot (clear face) and flood (frosted face).
Rapid Start Fluorescent Lamp - A fluorescent lamp designed for operation with a ballast that provides a low-voltage winding for preheating the electrodes and initiating the arc without a starting switch or the application of high voltage.
Rated Lamp Life - The point in hours where 50% of lamps initially started will still be operating.
Raw Footcandles - Same as footcandles. This term is sometimes used in order to differentiate between ordinary footcandles and ESSAY footcandles. (Footcandles or Raw Footcandles refer only to the quantity of illumination. ESSAY footcandles refer to task visibility by considering both the quantity and quality of illumination.)
Reflectance - Sometimes called reflectance factor. The ratio of reflected light to incident light (light falling on a surface). Reflectance is generally expressed in percent
Reflected Glare - Glare resulting from specular reflections of high luminances in polished or glossy surfaces in the field of view. It usually is associated with reflections from within a visual task or areas in close proximity to the region being viewed.
Reflection - Light striking a surface is either absorbed, transmitted, or reflected. Reflected light is that which bounces off the surface, and it can be classified as specular or diffuse reflection. Specular reflection is characterized by light rays which strike and leave a surface at equal angles. Diffuse reflection leaves a surface in all directions.
Reflector - A piece of material with a reflective surface that directs radiant energy (light)in a desired direction.
Reflector Lamp - A light source with an integral reflector, usually a silver or aluminum coating on the bulb.
Refraction - The process by which the direction of a ray of light changes as it passes obliquely from one medium to another in which its speed is different
Relamping - A project where the existing lighting fixtures at a facility are, as a group, cleaned and new lamps are installed. This is typically scheduled around projected life expectancy to reduce the day-to-day interruptions of failing aged lamps.
Retrofit - Refers to upgrading a fixture, room, building, etc., by installing new parts or equipment.
Romex - A cable comprised of flexible plastic sheathing inside of which are two or more insulated wires for carrying electricity.
Room Cavity Ratio (RCR) - A numerical relationship of the vertical distance between work plane height and luminaire mounting height to room width and length. It is used with the Zonal Cavity method of calculating average illumination levels.
Rough Service Lamps - Incandescent lamps designed with extra filament supports to withstand bumps, shocks and vibrations with some loss in lumen output.
