Light_Vocabulary

====**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. ====

====**Ballast**: an electrical device used with fluorescent and HID (high intensity discharge) lamps (light bulbs) to supply sufficient voltage to start and operate the lamp but then to limit the current during operation ====

====**Dimmer**: a device in an electrical circuit used for varying the brightness of lamps in a lighting installation. Dimming controls are ideal for almost any type of room because they can change the amount of lighting to suit each mood or activity and they can help you look good. The use of dimmers with incandescent, xenon, and halogen light sources also **//increases//** the life of the lamps and //**decreases**// the use of electrical energy. ====

====**Glare**: direct glare is caused by light coming directly to the eye from a light source. Indirect glare is light reflected from a surface in the direction of the eye. Both can harm vision and cause visual discomfort or disability. ====

====**Louver**: a type of “screen” made of translucent or opaque material and geometrically designed to prevent lamps from being viewed directly within a given angle. Louvers are intended to minimize direct or indirect glare. ====

====**Neodymium**: a rare earth element discovered in 1885 with an atomic number of 60 in the Periodic Table of Elements. It is a fairly common silvery metal that is used to make slightly purple glass envelopes for incandescent light bulbs, eye protection goggles for welding and glass blowing, laser rods, filters to color correct light for art displays, and lenses used by astronomers to calibrate spectrometers, optical instruments used for analyzing light. Using this substance in an incandescent light bulb makes it less "yellowish" and more like natural outdoor light; however, the use of these "daylight" light bulbs can "expose" the flaws or inconsistencies in things. ====

====**Torchiere**: a tall floor lamp that provides indirect lighting with its light source located within a reflecting bowl that directs the light upward, which then reflects off the ceiling ==== 
 * [|Home] > Illustrated Glossary of Lighting Terms by Pegasus Lighting ||

[|10] =Illustrated Glossary of Lighting Terms by Pegasus Lighting= ||
 * || * [|AC]
 * [|Accent Lighting]
 * [|Alabaster]
 * [|A-Line Lamp]
 * [|Alternating Current (AC)]
 * [|Ambient Lighting]
 * [|Area Lighting]
 * [|Baffle]
 * [|Ballast]
 * [|Barn Doors]
 * [|Base]
 * [|Basket Troffer]
 * [|Bayonet Base]
 * [|Beam Spread]
 * [|Bollard]
 * [|Brick Light]
 * [|Bulb]
 * [|cd]
 * [|Cable Lighting System]
 * [|Candela (cd)]
 * [|Cathode]
 * [|Cave Effect]
 * [|CCFL]
 * [|CFL]
 * [|Chandelier]
 * [|Circline]
 * [|Colored Glass Filter]
 * [|Color Rendering Index]
 * [|Color Temperature]
 * [|Compact Fluorescent Lamp]
 * [|Cornice Lighting]
 * [|Cove Lighting]
 * [|CSA]
 * [|Dimmer]
 * [|Direct Current]
 * [|Downlight]
 * [|Efficacy]
 * [|Emergency Lighting]
 * [|ER Lamp]
 * [|ETL] || * [|Faceplate]
 * [|Filament]
 * [|Flexible Track Lighting System]
 * [|Floodlight]
 * [|Fluorescent Lamp]
 * [|Foot-Candle]
 * [|Four-Way Switch]
 * [|General Lighting]
 * [|Glare]
 * [|Halogen Lamp]
 * [|Hardwired]
 * [|HID Lamp]
 * [|High Pressure Sodium Lamp]
 * [|Household Wire]
 * [|Illuminance]
 * [|Incandescence]
 * [|Incandescent Lamp]
 * [|Infrared Radiation]
 * [|Initial Lumens]
 * [|Instant Start]
 * [|Inverse Square Law]
 * [|IP Ratings]
 * [|Lamp]
 * [|Layers of Light]
 * [|LED]
 * [|LEED]
 * [|Light Fixture]
 * [|Light Source]
 * [|Light Trespass]
 * [|Linear Spread Lens]
 * [|Line Voltage]
 * [|Louver]
 * [|Low Voltage]
 * [|Lumen]
 * [|Luminaire] || * [|Mercury Vapor Lamp]
 * [|Metal Halide Lamp]
 * [|MOL]
 * [|MR11]
 * [|MR16]
 * [|Neodymium]
 * [|Opaque]
 * [|Open Circuit]
 * [|Parallel Circuit]
 * [|PAR Lamp]
 * [|Pendant]
 * [|PL Lamp]
 * [|Portable Lamp]
 * [|Quick Connector]
 * [|Radio Frequency Interference (RFI)]
 * [|Rapid Start]
 * [|Rated Life]
 * [|Recessed Downlight]
 * [|R Lamp]
 * [|RLM]
 * [|ROMEX® Wire] || * [|Sconce]
 * [|Security Lighting]
 * [|Series Circuit]
 * [|Shield]
 * [|Silhouetting]
 * [|Single-Pole Switch]
 * [|Sky Glow]
 * [|Snoot]
 * [|Solite Lens]
 * [|Spill Light]
 * [|Splice]
 * [|Spread Lens]
 * [|Starter]
 * [|Step Light]
 * [|Tandem Wiring]
 * [|Task Lighting]
 * [|Terminal Block]
 * [|Three-Way Switch]
 * [|Torchiere]
 * [|Transformer]
 * [|Translucent]
 * [|Transparent]
 * [|Troffer]
 * [|UL]
 * [|Uplight]
 * [|UV]
 * [|Ultraviolet Radiation]
 * [|Valance Lighting]
 * [|Vandal Resistant]
 * [|Vapor-Tight Luminaire]
 * [|Voltage]
 * [|Voltage Drop]
 * [|Wall Grazing]
 * [|Wall Sconce]
 * [|Wall Washing]
 * [|Wattage]
 * [|Work Plane]
 * [|Xenon Lamp] ||
 * [[image:http://ep.yimg.com/ca/Img/trans_1x1.gif width="1" height="10"]] ||
 * **AC**: see [|alternating current]
 * Accent Lighting**: lighting that is used to accent or highlight a particular object such as a work of art. To be effective accent lighting should be approximately four or five times the level of ambient light in the room, area, or space. House plants can be accented by aiming an uplight at the wall behind the plant, creating a dramatic silhouette of the plant against the wall. To learn more about this topic click [|Accent Lighting].


 * 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.|| **A-Line Lamp**: the type of incandescent light bulb that is generally used in most indoor residential lighting applications. From now until January 1, 2014 the most common standard screw-base incandescent household (A-line) light bulbs will be phased out in the U.S. Clear, frosted, soft white, and daylight light bulbs will be phased out but specialty colors and shapes will not be. The new standards for these light bulbs are //technology neutral// so any technology that can meet the new standards can be used - including [|fluorescent], halogen IR, high- efficiency incandescent, [|LEDs], and any technologies still to be developed. ||= [[image:http://images.pegasuslighting.com/general/glossary/T222406-48.jpg width="48" height="77" caption="A-Line Incandescent Lamp"]] ||
 * ^  ||= **A-Line Shape Incandescent Lamp** ||


 * Alternating Current (AC)**: the flow of electricity (electric current) in a circuit that frequently alternates direction every second. In the USA, the standard frequency of alternating current is 60 Hz (hertz or cycles/second) and AC (as opposed to direct current) is generally the method for delivering electric power to homes and buildings.

**Ambient Lighting**: [|general lighting] that usually lights up an entire space

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 * Area Lighting**: a landscape lighting term that refers to the lighting of large landscaped areas, usually with [|floodlights]
 * Baffle**: in lighting this is usually a grooved surface that deflects and controls the “flow” of light to soften it and minimize reflected glare. Baffle trims (sometimes called step baffle trims or stepped baffle trims), made of plastic or metal, are often integral parts of recessed downlights. They are often colored a flat black to absorb some of the light but can have other finishes such as flat white, brushed copper, or brushed nickel.

**Ballast**: an electrical device used with [|fluorescent] and [|HID] (high intensity discharge) lamps (light bulbs) to supply sufficient [|voltage] to start and operate the lamp but then to limit the current during operation


 * Barn Doors**: 2 or 4 adjustable opaque plates attached to the front of a [|luminaire], such as a track fixture or a theatrical spotlight, which are used to shape and focus the light on a designated area, such as a framed work of art or a stage scene


 * Base**: the portion of a lamp (light bulb) that provides a means of physically and electrically connecting the lamp to a socket or lampholder within a luminaire


 * Basket Troffer**: a troffer whose light sources are concealed by curved opaque shielding called "baskets", which are often perforated with a pattern of small holes. This type of troffer provides both direct lighting through the perforations and indirect lighting by bouncing light up from the basket and then off the upper light-colored opaque parts of the troffer.


 * Bayonet Base**: a type of lamp base with pins that serve to lock the lamp into slots in the lamp socket of a luminaire. The bayonet base got its name from the method used by soldiers to mount bayonets on their rifles.


 * Beam Spread**: a measure of the spread of light from a reflectorized light source, a special-shaped lamp with a reflective coating inside the bulb to direct the light forward. The beam spread may be very narrow (narrow spot), very wide (wide flood), or something in-between (narrow flood, for example). Examples of "reflectorized light sources" are MR11, MR16, PAR20, PAR30, PAR38, R40, ER30, and BR30 lamps.


 * Bollard**: an outdoor [|luminaire] that is a short (usually about 2-4 feet in height) but very sturdy vertical post with the light source located at or near the top. Bollards are typically used to light walkways in commercial settings.


 * Brick Light**: a light fixture (usually the size of a brick) that can be recessed in a brick wall with its face parallel to the surface of the brick surface in order to light a walkway, a step, a landing, or a path

[|Back to top] **cd**: see [|Candela]
 * Bulb**: a colloquial term for a lamp. In the lighting industry, the term, bulb, refers only to the glass envelope of the lamp. Some lighting professionals contemptuously refer to "bulbs" as those things that are planted in the ground.


 * Cable Lighting System**: a [|low voltage] lighting system where the mechanism holding the light fixtures and conducting electricity to those fixtures is a pair of cables.


 * Candela (cd)**: the unit of measurement of luminous intensity (cd) of a light source in a given direction.


 * Cathode**: an electrode that emits electrons. A [|fluorescent lamp] cathode emits or discharges electrons to the cathode at the other end of the lamp (light bulb).


 * Cave Effect**: an unwanted consequence often associated with parabolic troffers, the cave effect is created when the light fixtures in a room apply no direct light to the upper part of walls due to an extreme cut-off angle

Fluorescent Lamp w/Medium Screw-In Base** ||
 * **CCFL**: a cold cathode fluorescent lamp is a type of fluorescent lamp in which the cathode (an electron-emitting electrode inside the lamp) is not independently heated although the cathode can become quite hot once the CCFL has been operating. Screw-in CCFLs come in several different wattages (present range is 3W to 18W) and several different shapes (spiral, globe, reflector, A-line, torpedo) and are generally characterized by a very thin glass envelope (2mm-4mm in diameter), a longer rated life than compact fluorescent lamps (often 25,000 hours), and a very good range of dimmability (down to 30%). ||= [[image:http://images.pegasuslighting.com/general/glossary/screw-in-ccfl.jpg width="100" height="48" caption="Cold Cathode Fluorescent Lamp w/Medium Screw-In Base"]] ||
 * ^  ||= **Cold Cathode


 * CFL**: see [|compact fluorescent lamp]


 * Chandelier**: a chandelier is often the focal point of the dining room. As such it should be hung about 30 inches above the tabletop and should be at least 6 inches narrower than the table on each side.


 * Circline**: a type of fluorescent lamp that is made up of a circular tube of glass; when placed in a light fixture the ballast that powers this type of lamp is usually located in the center of the circline lamp

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 * **Colored Glass Filter**: this term means that the glass is formed with the color **//in//** the glass as opposed to the color being coated **//on//** the surface. This is accomplished by mixing various metal oxides in the glass composition. These colored glass filters are primarily used for aesthetic purposes in lighting. They are //**not**// designed for the precise control of the spectral bands, as are optical color filters (dichroic filters). To learn more about this topic click [|Colored Glass Filters]. ||= [[image:http://images.pegasuslighting.com/general/glossary/GlassFilters_61.jpg width="61" height="66" caption="Colored Glass Filters" link="http://www.pegasuslighting.com/colored-glass-light-filters.html"]] ||
 * ^  ||= **Colored Glass Filters** ||
 * Color Rendering Index (CRI)**: a measure of a lamp’s ability to render colors accurately. The scale ranges from 1 (low pressure sodium) to 100 (the sun). A CRI of 85 is considered to be very good.

These tables may help you better understand the concept of Color Temperature.
 * Color Temperature**: a measure of the color appearance of a light source which helps describe the apparent "warmth" (reddish) or "coolness" (bluish) of that light source. Generally, light sources below 3200K are considered "warm;" while those above 4000K are considered "cool" light sources. The color temperature of a lamp has nothing to do with how hot the lamp will get or how much heat is given off by the lamp. The letter, K, stands for Kelvin.
 * ~ APPROX. COLOR TEMPERATURE ||~ ASSOCIATED EFFECTS & MOODS ||~ APPROPRIATE APPLICATIONS ||
 * 2700K || Friendly, Personal, Intimate || Homes, Libraries, Restaurants ||
 * 3500K || Friendly, Inviting, Non-threatening || New Offices,Public Reception Areas ||
 * 4100K || Neat, Clean, Efficient || Older Offices, Classrooms, Mass Merchandisers ||
 * 5000K || Bright, Alert, Exacting Coloration || Graphics, Jewelry Stores, Medical Exam Areas, Photography ||


 * ~ APPROX. COLOR TEMPERATURE ||~ LIGHT SOURCE ||
 * 1600K || Sunrise or Sunset ||
 * 1800K || Candlelight ||
 * 1800K || Gaslight ||
 * 2800K || Household Incandescent Lamp ||
 * 3000K || Warm White Fluorescent Lamp ||
 * 3500K || Neutral White Fluorescent Lamp ||
 * 4100K || Cool White Fluorescent Lamp ||
 * 5000K || Professional Light Booth ||
 * 5200K || Bright Midday Sun ||
 * 6500K || Heavily Overcast Sky ||


 * Compact Fluorescent Lamp (CFL)**: a generic name used for a whole family of small, single-ended [|fluorescent lamps] with a folded, bridged, or spiral glass tube design and with high color rendering ([|CRI] > 80) and a long life (> 8,000 hours). To learn more about this topic click [|CFL Information].


 * Cornice Lighting**: a lighting system comprised of light sources shielded by a panel parallel to the wall and attached to the ceiling and distributing light over the wall.

in a Restaurant** ||
 * **Cove Lighting**: a lighting system comprised of light sources shielded by a ledge or recess, and distributing light over the ceiling and possibly the upper part of the wall. To learn more about this topic click [|Cove Lighting]. ||= [[image:http://images.pegasuslighting.com/general/glossary/CoveLightinginRestaurant100.jpg width="100" height="81" caption="Cove Lighting in a Restaurant" link="http://www.pegasuslighting.com/cove-lighting.html"]] ||
 * ^  ||= **Cove Lighting

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 * CSA**: the Canadian Standards Association, like UL and ETL in the USA, is a not-for-profit membership-based association serving business, industry, government, and consumers in Canada and the global marketplace. It is an organization that works in Canada and around the world to develop safety standards that address real needs, such as enhancing public safety and health, advancing the quality of life, and helping to preserve the environment.
 * **Dimmer**: a device in an electrical circuit used for varying the brightness of lamps in a lighting installation. Dimming controls are ideal for almost any type of room because they can change the amount of lighting to suit each mood or activity and they can help you look good. The use of dimmers with incandescent, xenon, and halogen light sources also **//increases//** the life of the lamps and //**decreases**// the use of electrical energy. (Please see the Table below.) To learn more about this topic click [|Dimmer FAQ] and [|Valuable Information about Dimmers].||~ Percentage Dimmed ||~ Energy Savings ||~ Lamp Life Increase ||
 * 10% || 10% || 2 x ||
 * 25% || 20% || 4 x ||
 * 50% || 40% || 20 x ||
 * 75% || 60% || > 20 x || ||= [[image:http://images.pegasuslighting.com/general/glossary/newskylark.jpg width="71" height="109" caption="Preset Dimmer with Slider" link="http://www.pegasuslighting.com/dimmers.html"]] ||
 * ^  ||= **Preset Dimmer with Slider** ||


 * Direct Current**: electric current without alterations. DC current is usually supplied by a battery, a transformer, or photovoltaic cells.

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 * **Downlight**: a small light fixture recessed into the ceiling that usually concentrates the light in a downward direction. Synonyms: recessed downlight, “can”, recessed can. To learn more about this topic click [|Recessed Lighting]. ||= [[image:http://images.pegasuslighting.com/general/glossary/pnt5020.jpg width="92" height="69" caption="Downlight with a Black Baffle and White Trim" link="http://www.pegasuslighting.com/recessed-lighting.html"]] ||
 * ^  ||= **Downlight with a White Baffle and White Trim** ||
 * Efficacy**: a measure used to compare light output to energy consumption. Efficacy is measured in [|lumens] per watt. A 100-watt light source producing 1750 [|lumens] of light has an efficacy (efficiency) of 17.5 [|lumens] per watt (L/W).
 * ~ LIGHT SOURCE ||~ EFFICACY ||
 * Edison's first lamp || 1.4 L/W ||
 * Infrared Lamps || 6-9 L/W ||
 * Incandescent Lamps || 10-40 L/W ||
 * Fluorescent Lamps || 35-100 L/W ||
 * Mercury Vapor Lamps || 50-60 L/W ||
 * Metal Halide Lamps || 80-125 L/W ||
 * High Pressure Sodium Lamps || 100-140 L/W ||
 * Theoretical max for white light || 225 L/W ||

Emergency Lighting** ||
 * **Emergency Lighting**: lighting used when the normal lighting fails. To learn more about this topic click [|Troubleshooting Tips for Emergency Lighting]. ||= [[image:http://images.pegasuslighting.com/general/glossary/LEDEXITSignCombo_150.jpg width="150" height="83" caption="LED Exit Signs with Emergency Lighting" link="http://www.pegasuslighting.com/emergency-lights.html"]] ||
 * ^  || **LED Exit Signs with


 * ER Lamp**: a type of incandescent reflector lamp with the reflector shaped like an ellipsoid (a 3-dimensional ellipse) with the lamp's filament located at one of the two foci of the ellipsoid so that the light is focused directly in front of the lamp at the second foci

Symbol** || [|Back to top]
 * **ETL**: ETL, like Underwriters Laboratories, Inc. ([|UL]), is an independent, not-for-profit product safety testing and certification organization. Throughout its long history its name has changed several times. Thomas A. Edison established the Lamp Testing Bureau in 1896. In 1904 Edison renamed his Lamp Testing Bureau the Electrical Testing Laboratories (ETL). In 1977 ETL officially changed its corporate name to ETL Testing Laboratories and in 1996 ETL was renamed the Intertek Testing Services, Ltd. ||= [[image:http://images.pegasuslighting.com/general/ETL25.gif width="25" height="26" caption="ETL Symbol for Intertek Testing Services, Ltd."]] ||
 * ^  ||= **ETL
 * (**NOTE**: ETL Testing Laboratories, originally organized by the Edison Illuminating Companies, has been conducting electrical performance and reliability tests since 1896. Intertek Testing Services (ITS), which acquired ETL Testing Laboratories from Inchcape in 1996, is recognized by OSHA as a Nationally Recognized Testing Laboratory (NRTL) just as Underwriters Laboratories (UL), the Canadian Standards Association (CSA) and several other independent organizations are recognized. A federal law passed in 1988 established the NRTL program to eliminate provisions that explicitly required or implied that product certification be performed only by standard-writing companies such as UL. Since each NRTL must meet the same OSHA requirements of competency, NRTLs recognized for the same product safety test standard are considered as equivalent in their capability to certify to that standard.) ||=  ||
 * Faceplate**: the metal or plastic plate installed over an on/off switch, dimmer, or receptacle, which covers the wall opening and protects the wiring inside the junction box

**Filament**: a tungsten wire that [|incandesces] or lights up when an electric current runs through it.


 * Flexible Track Lighting System**: a [|low voltage] **//or//** a [|line voltage] lighting system where the suspended track (sometimes called a monorail) holding the light fixtures in place and also conducting electricity to those fixtures can be bent into creative shapes.


 * Floodlight**: a broad-beamed high intensity artificial light source

Lamp** ||
 * **Fluorescent Lamp**: a low-pressure mercury electric-discharge lamp (light bulb) in which a phosphor coating on the inside of the glass tubing transforms some of the ultraviolet energy created inside the lamp into visible light. To learn more about this topic click [|Fluorescent Lamps]. || [[image:http://images.pegasuslighting.com/general/glossary/T8Lamp_80.jpg width="80" height="80" caption="Fluorescent Lamp" link="http://www.pegasuslighting.com/fluorescent-light-bulbs.html"]] ||
 * ^  || **Fluorescent


 * Foot-Candle**: the amount of light reaching a subject. The commonly United States unit of measurement of lighting level (illumination) is the foot-candle (fc). The international unit of measurement of lighting level (Illumination) is the lux (lx). The relationship between the lux and the foot-candle is 1 fc = 10.76 lux.

[|Back to top]
 * Four-Way Switch**: a wall switch that allows three switches like this to control one lighting system. Whenever you flip one of the four-way switches in a given circuit, the light changes its state; that is, if the light was on, it then turns off and if the light was off, it then turns on.
 * General Lighting**: substantially uniform lighting of a space without providing for special local lighting requirements like [|task lighting] or [|accent lighting].

||
 * Glare**: direct glare is caused by light coming directly to the eye from a light source. Indirect glare is light reflected from a surface in the direction of the eye. Both can harm vision and cause visual discomfort or disability.