Light_Vocabulary

A consensus-based organization which coordinates voluntary standards for the physical, electrical and performance characteristics of lamps, ballasts, luminaires and other lighting and electrical equipment
 * ANSI (American National Standards Institute)**

An auxiliary piece of equipment required to start and to properly control the flow of current to gas discharge light sources such as [|fluorescent] and [|high intensity discharge (HID)] lamps. Typically, magnetic ballasts (also called electromagnetic ballasts) contain copper windings on an iron core while electronic ballasts are smaller and more efficient and contain electronic
 * Ballast**

**Beam Angle**The angular dimension of the cone of light from reflectorized lamps (such as [|R] and [|PAR] types) encompassing the central part of the beam out to the angle where the intensity is 50% of maximum. The beam angle sometimes called "beam spread" is often part of the ordering code for the reflectorized lamps. Example: The 50PAR30/HIR/NFL25 is a 50 watt PAR30 narrow flood lamp with a beam angle of 25 degrees (See [|FIELD ANGLE]).

**Cathode**Metal filaments that emit electrons in a fluorescent lamp. Negatively charged free electrons emitted by the cathode are attracted to the positive electrode (anode), creating an electric current between the electrodes.

**ChromaFit**A GE brand name for metal halide lamps designed to operate on HPS ballasts, allowing a user to switch from the yellowish color of HPS to the white color of metal halide without changing ballasts. These products are available in both quartz metal halide and ceramic metal halide (CMH) versions.

**Daylight Harvesting**Lighting design for building interiors that makes of daylight as a way of reducing energy consumption.

**GE Edison Award**An annual competition where lighting designers submit their best projects. The entries are judged by an international panel and awards are presented at a banquet accompanying Light Fair, the North American trade show for the lighting industry.

**Flicker**The periodic variation in light level caused by AC operation that can lead to strobe effects.

**Flood**Used to refer to the beam pattern of a reflector lamp, which disperses the light over a wide beam angle, typically 20 degrees or more. ("Flood" as opposed to "spot")

**Floodlight**A luminaire used to light a scene or object to a level much brighter than its surroundings. Usually floodlights can be aimed at the object or area of interest.

**Input Watts**The total power input to the ballast which includes lamp watts and ballast losses. The total power input to the fixture is the input watts to the ballast or ballasts and is the value to be used when calculating cost of energy and air conditioning loads.

**Parallel Lamp Operation**Refers to ballasts that employ multiple output current paths from a single ballast to allow lamps to operate independent of one another, allowing other lamps operated by the ballast to remain lit should companion lamp(s) fail.

**PAR Lamp**PAR is an acronym for parabolic aluminized reflector. A PAR lamp, which may utilize either an incandescent filament, a halogen filament tube or a HID arc tube, is a precision pressed-glass reflector lamp. PAR lamps rely on both the internal reflector and prisms in the lens for control of the light beam.

**PCB (Polychlorinated Biphenyls)**Chemical pollutant formerly used in ballast capacitors that were part of ballasts. It is now illegal to use PCB's and most such ballasts have been replaced over time.

**Phosphor**An inorganic chemical compound processed into a powder and deposited on the inner glass surface of fluorescent tubes and some mercury and metal-halide lamp bulbs. Phosphors are designed to absorb short wavelength ultraviolet radiation and to transform and emit it as visible light (See [|FLOURESCENCE]).

**Reflector Lamp (R)**A light source with a built-in reflecting surface. Sometimes, the term is used to refer specifically to blown bulbs like the R and ER lamps; at other times, it includes all reflectorized lamps like PAR and MR.

A Color Designation for GE Ceramic Metal Halide Lamps with superior Color Rendering ~ 90
 * SPXX**

**Wavelength**The distance between two neighboring crests of a traveling wave. The wavelength of light is between 400 and 700 nanometers.


 * Alabaster**: genuine alabaster is a very fine variety of crystalline gypsum (hydrous calcium sulfate) found in nature. It is [|translucent] and its color is often white, pearly, or silky colorless but it, more often than not, has subtle reddish-brown bands of iron oxide running through it. It is often used for decorative objects such as light fixtures or figurines. Some light fixtures use //**faux**// alabaster, which is usually man-made glass. Both genuine and faux alabaster can be very attractive. The faux alabaster is generally much less expensive while real alabaster can lose some of its coloration over time. Real alabaster is expensive simply because quarrying it is costly and there is huge amount of waste when it is shaped, finished, and polished. Genuine alabaster is a minimum of 3/8in thick and weighs at least twice as much as imitations and has translucent and dark bands that are completely random in shape, size, and location. Since alabaster is a soft, porous stone it should be treated gently and never cleaned with detergents or abrasives. Instead, wipe alabaster with a slightly damp (not wet), soft cloth. Furthermore, heating alabaster for long periods of time with a high-wattage light bulb may drive out the residual water in the alabaster and turn it completely white.