Light+Vocabulary

Alabaster**: genuine alabaster is a very fine variety of crystalline gypsum (hydrous calcium sulfate) found in nature.
 * WORDS THAT I DON'T KNOW ¿? **
 * A*
 * ANSI (American National Standards Institute):** 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 Ballast Type:** Ballast type used to operate lamp in accordance with ASNI standard.
 * ANSI Codes:** These are 3-letter codes assigned by the American National Standards Institute. They provide a system of assuring mechanical and electrical interchangeability among similarly coded lamps from various manufacturers.


 * B***
 * Ballast:** 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.
 * Ballast Efficacy Factor (BEF):** Defined as ballast factor divided by input watts. The value is used to evaluate various lighting systems based on light output and power input. The BEF can only be used to compare systems operating the same type and quantity of lamps.
 * Ballast Factor (BF):** This is the percentage of a lamp's rated [|lumen] output that can be expected when operated on a specific, commercially available ballast.
 * Ballast Hum:** Sound generated by the vibration of laminations in the iron core of the transformer or inductor present in the ballast.
 * Ballast Losses:** Power or energy dissipated in the ballast as heat and not converted to lamp energy.

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.
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 * Core:** Component of electromagnetic ballast that is surrounded by the coil. Core is comprised of steel laminations or solid ferrite material.
 * Core & Coil Ballast:** A ballast that uses a "Core & Coil" assembly to operate fluorescent or HID lamps. Refers to copper windings on a steel core.


 * D***
 * Distance Between Legs:** For U-shaped Fluorescent lamps, this measurement is the average distance between the inner walls of the legs.
 * Distance Between Leg Centers:**For U-shaped Fluorescent lamps, this measurement is the average distance between the centers of each leg.
 * Distance Outside Legs:** For U-shaped Fluorescent lamps, this measurement is the average distance to the outside of each leg.

ECE R37 Code:** European Common Market Regulation 37 standard lamp number.
 * E*

Field 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 10% of maximum. **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")
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Glare:** Visual discomfort caused by excessive brightness is called discomfort glare.
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Ignitor:** An electronic device providing a high voltage pulse to initiate an electrical discharge. Typically, the ignitor is paired with or is a part of the ballast.
 * I*
 * Inverse Square Law:** Formula stating that if you double the distance from the light source, the light level goes down by a factor of 4, if you triple the distance, it goes down by a factor of 9, and so on.
 * Isocandela Plot:** A plot with lines connecting points of equal luminous intensity around a source.
 * Isolux Plot (or Isofootcandle Plot):** A line plotted to show points of equal illuminance (lux or footcandles) on a surface illuminated by a source or sources.
 * Inverse Square Law**: a law that states that the illuminance (E) at a point on a plane perpendicular to the line joining the point and a source is inversely proportional to the square of the distance (d) between the source and the plane, E = I/d².

Light Emitting Diode (LED):** A solid that directly converts electrical impulses into light. Some LED's today incorporate fluorescent materials to change the color characteristics of the emitted light. Mesopic:** Typically referring to nighttime outdoor lighting conditions, the region between PHOTOPIC and SCOTOPIC vision.
 * L*
 * Lumens:** A measure of the luminous flux or quantity of light emitted by a source. For example, a dinner candle provides about 12 lumens. A 60-watt Soft White incandescent lamp provides about 840 lumens.
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 * N***
 * NOM:** Laboratory that sets safety standards for building materials, electrical appliances and other products for Mexico.
 * Non-PCB Capacitor:** Capacitor used in ballasts to help provide power factor correction. Contains no polychlorinated biphenyls and meets EPA requirements.
 * Neodymium**: a rare earth element discovered in 1885 with an atomic number of 60 in the Periodic Table of Elements.

Open Fixture Rated:** Lamps that are approved for burning in open fixtures (as opposed to enclosed fixtures which have an acrylic lens or plate glass enclosure).
 * O*

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.
 * P*
 * Preheat Circuit:** A type of fluorescent lamp-ballast circuit used with the first commercial fluorescent lamp products. A push button or automatic switch is used to preheat the lamp cathodes to a glow state. Starting the lamp can then be accomplished using simple "choke" or reactor ballasts.
 * Programmed Rapid Start:** Lamp starting method which preheats the lamp filaments while not allowing the lamp to ignite and then applies the open circuit voltage (OCV) to start the lamp.

Quad:** Generally refers to a compact fluorescent lamp containing 4 U-shaped tubes.
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Rapid Start Circuit:** A fluorescent lamp-ballast circuit that utilizes continuous cathode heating, while the system is energized, to start and maintain lamp light output at efficient levels.
 * R*
 * Rated Lamp Life:** For most lamp types, rated lamp life is the length of time of a statistically large sample between first use and the point when 50% of the lamps have died. It is possible to define "useful life" of a lamp based on practical considerations involving lumen depreciation and color shift.

Scotopic:** Vision where the rods of the retina are exclusively responsible for seeing, typically like the light levels in the countryside on a moonless, starlit night.
 * S*
 * Self-Ballasted Lamps:** A discharge lamp with an integral ballasting device allowing the lamp to be directly connected to a socket providing line voltage.
 * Spacing to Mounting Height Ratio:** Ratio of fixture spacing (distance apart) to mounting height above the work plane; sometimes called spacing criterion.
 * Sunburn:** Skin reddening and inflammation caused by overexposure to sources containing UV-B and/or UV-C.
 * Silhouetting**: a landscape lighting technique used to create a distinct outline or silhouette of plants or other objects.

Total Harmonic Distortion (THD):** A measure of the distortion of the input current on alternating current (AC) power systems caused by higher order harmonics of the fundamental frequency (60Hz in North America). THD is expressed in percent and may refer to individual electrical loads (such as ballast) or a total electrical circuit or system in a building.
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 * Troffer:** A long, recessed lighting unit, usually installed in an opening in the ceiling.

Uniform Code Council (UCC):** The 12 digit case code derived from the last 12 digits of the 14 digit SCC code on GE's case content label.
 * U*
 * Underwriters' Laboratories (UL):** A private organization which tests and lists electrical (and other) equipment for electrical and fire safety according to recognized UL and other standards.

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