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.
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Select the first letter of the word from the list above to jump to appropriate section of the glossary.
PAR Lamps - Parabolic aluminized reflector lamps which offer excellent beam control, come in a variety of beam patterns from very narrow spot to wide flood, and can be used outdoors unprotected because they are made of "hard" glass that can withstand adverse weather.
Parabolic Louvers - A grid of baffles which redirects light downward and provides very low luminaire brightness
Pattern Control - A blade, in the air passage of an air handling luminaire, which sets the direction of air flow from the luminaire.
Photocell - A light sensing device used to control luminaires and dimmers in response to detected light levels.
Photopic Vision - Refers to vision involving the cones of the eye; used in reference to the adaptation of the eye to illuminance of more than 3.4 candelas per square meter, or one footlambert. See "Scotopic Vision."
PL - Designation for a type of compact fluorescent lamp.
Plug-in Wiring - Electrical distribution system which has quick-connect wiring connectors.
Point Method Lighting Calculation - A lighting design procedure for predetermining the illuminance at various locations in lighting installations, by use of luminaire photometric data.
Polarization - The process by which the transverse vibrations of light waves are oriented in a specific plane. Polarization may be obtained by using either transmitting or reflecting media.
Polycarbonate - Material used in lenses that will not break or yellow
POMB - Position Oriented Mogul Base lamps - for horizontal burning positions
Positive Cash Flow - when referred to as part of a lighting upgrade, this is a comparison of estimated savings to cost. With 100 percent project financing it is possible to have an immediate positive cash flow once the project starts.
Power Factor - Ratio of: watts over volts x amperes; Power factor in lighting is primarily applicable to ballasts. Since volts and watts are usually fixed, amperes (or current) will go up as power factor goes down. This necessitates the use of larger wire sizes to carry the increased amount of current needed with Low power Factor (L.P.F.) ballasts. The addition of a capacitor to a L.P.F. ballast converts it to a H.P.F. ballast.
Preheat Fluorescent Lamp - A fluorescent lamp designed for operation in a circuit requiring a manual or automatic starting switch to preheat the electrodes in order to start the arc.
Pulse start metal halide lamps - Pulse start metal halide lamps incorporate a high voltage ignitor similar to the high pressure sodium. The result is a run up time of two minutes, one-half that of standard metal halide and equal to high pressure sodium. The restrike time is similarly affected, being cut by 80% down to three to four minutes. The efficiency (lumen/watt) of pulse start systems is anywhere from a 25% to 50% increase in lumens/watts, 90 to 110 up from probe start at 60-85. Lumen maintenance also increases by up to 30%, up to 85% from 65%. The change in color (color shift) of pulse start due to the improved crest factor and lamp wattage regulation is reduced by up to 2/3 of the comparable probe start metal halide or less than 200°K over the life of the lamp versus 600°K for probe start. A CRI of up to 85 represents a 30% improvement over traditional probe start metal halide sources (four times that of high pressure sodium). Finally, the high voltage ignitor allows a much colder starting temperature compared to standard metal halide units, -40°F/-40°C to -20°F/-30°C.
