Lighting A to Z

GlossaryRod Photoreceptors in the retina containing light-sensitivepigments. Rods probably play no part in color discrimination.Rough Service Lamps Incandescent lamps designedwith extra filament supports to withstand bumps, shocks,and vibrations.SAD Seasonal Affective Disorder is a type of depression, afeeling of lethargy, that may be related to the reduction ofsunlight as days grow shorter. Also known as “Winter TimeBlues” or “Cabin Fever”. It is sometimes treated with “FullSpectrum” lighting.Shielding An arrangement of light-controlling material toprevent direct view of the light source.Spacing The distance between the centers of two successiveluminaires in an installation.Spacing to Mounting Height Ratio (S/M) The ratio ofthe distance between luminaire centers to the height above thework plane. Gives the maximum spacing of luminaires at whicheven illumination will be provided.Speed of Light Approximately 186,000 miles per second.Spill Light The scattered light of a floodlight falling outsidethe beam that is usually considered wasted light.Spotlight A (small) projector giving concentrated light usuallynot more than 20˚ beam spread.Stand-by Lighting That part of emergency lighting thatenables normal activities to continue substantially unchanged.Starter Device for starting a fluorescent lamp that providesfor the necessary preheating of the electrodes and/or causes avoltage surge in combination with the series ballast.Task Lighting Lighting for a specific visual task, additional toand controlled separately from the general lighting. The term isoften applied to lighting designed to illuminate a particularly smallarea, e.g. a desk top.TCLP Toxic Characteristic Leaching Procedure. AUS Environmental Protection Agency test for non-hazardouswaste, a test designed to measure into the ecosystem. Philips ALTO substances that might dissolve® lamps pass this test.Lighting A–Z 53