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 Looking for explanation of special term of LED Lighting.

The following is not, nor is it intended to be, a complete list of lighting techniques, terms, or devices.
It is, rather, a sampling of definitions frequently used by the lighting industry.

a.f.f. “Above Finished Floor” - commonly used abbreviation when specifying the mounting height of fixtures, ceilings, etc
accent lighting directional lighting used to emphasize particular object or area. It focuses the observer's attention
acrylic  clear, translucent or white plastic material used to produce optical elements for light fixtures, i.e. lenses, louvers and refractors
acrylic lens flat plastic panel installed in the fixture to visually cover the lamps, and to lower glare by redirecting or diffusing lamp’s light output
acrylic refractor optical system made from acrylic plastic, similar to reflector, but designed to redirect small portion of lamp’s light output upwards and around the fixture, to create some level of indirect lighting or brighter perception of illuminated area
ambient lighting lighting throughout an area which produces general illumination
aperture opening on the fixture that light is radiated through towards the work plane
baffle a matte black or white element to shield light source from direct view of an observer at certain angles
ballast an electric or electronic device wired between power supply line and electric-discharge lamp. Ballast converts regular power to specific electrical conditions required for starting and operating discharge lamp.        More…
ballast core & coil magnetic ballast system consisting of several individual parts, i.e. coil and capacitor; that must be installed in a separate, approved enclosure.    Typically used with metal halide or high pressure sodium lamps
ballast cover removable part of light fixture designed to provide easy access to ballast, i.e. for servicing
ballast dimming specially designed ballast capable of dimming discharge lamps, usually fluorescent or very lately metal halide.        More…
ballast electronic high efficiency ballast that uses electronic circuitry to provide proper starting and operating electrical conditions for discharge lamp, or multiple lamps.     More...   
ballast factor the applicable output of lamp(s) operated on a ballast as compared to the output of lamp(s) when operated on the reference ballast used when the initial lamp lumen were determined by the lamp manufacturer. Typical high ballast factor ballast will increase the lamp’s lumens by 25%, i.e. 3650 vs. 2950 lumens from std. 4’ T8 lamp. Extremely feasible feature in high performance, indirect lighting luminaries.     More…
ballast f-can fully encapsulated ballast ready to be installed in the building without any additional enclosure
ballast loss amount of energy lost within the ballast, converted to internal heat.   In older systems ballast loss can amount to 20% of lamp’s energy, i.e. 40W F40 lamp that uses 48W with ballast connected
ballast magnetic older ballast design uses coils, magnetic transformer and capacitors to create proper starting and operating conditions for discharge lamp.    Hot operating and unreliable
ballast remote a ballast that is installed remotely from the fixture. Typical for architectural pendant luminaries where ballast is hidden in the ceiling system. Maximum allowed distance between ballast and luminaire is usually 12 feet.      More…  
ballast temperature operating ballast temperature is very critical to ballasts life expectancy. Older magnetic ballast run hotter and expect to last 5 – 10 years. Electronic ballasts run cooler due to much lowe ballast loses, and are expected to last 10 – 25 years.     More…
ballast warranty provided by the ballast manufacturer, it can range from one year to five years. Some manufacturers offer on-site warranty service or nominal labor allowance for failed ballasts covered by warranty.       More…
barn doors mechanical / optical accessory to track lighting fixture designed to provide “studio” look and/or functioning as mechanical shutter to partially reduce the size and intensity of lamp’s beam
Biax lamp same as PLL lamp, 12 – 21 inch long, high-lumen (4,800 lm. max), single-ended T5 compact fluorescent lamp.    Biax is a GE Lighting brand
black light typically fluorescent or metal halide lamp with special coating designed to absorb all visible light but transmit ultra-violet light at full. Used for special effects in bars, theaters, in combination with specially formulated glowing paints or plastic articles, etc.
bollard column-shaped cylindrical exterior light fixture with some sort of optical system, i.e. lens or radial louver, mounted on the top.    Typically used for path lighting of sidewalks and driveways
brightness the subjective attribute of any light sensation giving rise to the perception of light intensity
brightness - ceiling ceiling brightness is sometimes confused with glare. If ceiling is bright from direct, poorly designed luminaries, it is glaring bright. When ceiling is bright from softly diffused indirect lighting, it creates a perception of bright, comfortably illuminated space with zero glare.           More…
brightness - floor bright flooring material acts as a reflective material and can contribute to providing higher light levels with less luminaries
brightness- perception of subjective perception of light intensity as received by human eye. It is affected by overall balance of different elements: brightness of walls, floors and ceiling, light levels throughout the space, and relative brightness of surrounding environments.     More…
C.U.    coefficient of utilization Percentage of lamp's total light output, processed and distributed by a luminaire, received on the work-plane
candela the International System (SI) unit of luminous intensity. One candela is one lumen per steradian
candelabra base miniature incandescent screw-in lamp base used in decorative luminaries. Base code: E-14 Mini-Candelabra base code: E-11
canopy approx. 4 inches round or square plastic or metal junction box cover with strain relieve connector, that is used to hang and to power pendant luminaries
capsylite Sylvania brand of halogen PAR20, PAR30 and PAR38 lamps
ceiling - cathedral sloped drywall or open ceiling. Requires special sloped-ceiling rated recessed downlights and track lighting mounting hardware or fixture adapters
ceiling - drywall permanently enclosed, solid plaster ceiling. Plenum is accessible only through fixture opening(s) or specially installed access doors or panels
ceiling - open concept ceiling-less interior design.   Roof rafters or support structure above and all wiring, piping, ducts and other infrastructure are exposed. Usually much more expensive than enclosed ceiling systems with all infrastructure hidden in the plenum
ceiling - t-bar enclosed ceiling system consisting of permanently installed “inverted T” frame with openings filled with light weight acoustical ceiling panels. Most commonly used in commercial projects, T-bar ceiling provides the easiest access for installation or servicing of light fixtures.        More…
ceiling brightness ceiling brightness is sometimes confused with glare. If ceiling is bright from direct, poorly designed luminaries, it is glaring bright. When ceiling is bright from softly diffused indirect lighting, it creates a perception of bright, comfortably illuminated space with zero glare.     More…
ceiling height distance between floor and ceiling
ceiling tiles lightweight acoustical ceiling panels usually in 2 ft. x 4 ft. nominal size, designed to fit into T-bar ceiling
ceramic metal halide premium color rendering, newly designed metal halide lamp using one-piece ceramic discharge burner design.        More…
circline lamp round-shaped T9 fluorescent lamp for residential and special application luminaries. Low system efficacy. Three sizes available: 8”/22W/1100 lm, 12”/32W/1900 lm, 16”/40W/2000 lumens
clear reflector most commonly specified trim / optical system for compact fluorescent and other downlights where high efficiency lighting is required
clips plastic or metal elements to provide additional support to single-ended long compact fluorescent lamps
closed rated lamp H.I.D. lamp, metal halide or high pressure sodium, designed to be used only in luminaries with protective lens, that protects people and surrounding areas from flying pieces of hot glass in case of destructive breakdown of the lamp
closed rated luminaire commercial light fixture that can be operated only with protective lens in place, to protect people and surrounding areas from flying pieces of hot glass in case of destructive breakdown of the lamp
coefficient of utilization    (CU) percentage of lamp's total light output, distributed by a luminaire, received on the work-plane
color filters made from colored glass, color filters are accessory to track lighting or downlights used when special (theatrical) color effects are required
color gels made from thin, color plastic sheets; gels can be formed into sleeves and used with common fluorescent lamps to achieve special effects, i.e. colored uplighting.     More…
color rendering index A measure of a lamp’s ability to render colors accurately. The scale ranges from 1(low pressure sodium) to 100(the sun). The higher the CR (based upon a 0-100 scale), the better colors appear. A CRI of 80 is considered to be very good. (CRI) is a relative measure of the shift in surface color presentation of an object when lit by a particular lamp, compared with how the object would appear under a reference light source of similar color temperature. The higher the CRI of the light source, the "truer" it renders color
color temperature The concept of color temperature is based on the relationship between the temperature and radiation emitted by a theoretical standardized material, termed a black body radiator cooled down to a state in which all molecular motion has ceased. how cool or warm the light source appears: “Warm White” = 3000 Kelvin;  “Neutral White” = 3500 Kelvin;  “Cool White” = 4100 Kelvin and  “Daylight White” = 5000 or more Kelvin
compact fluorescent single-ended fluorescent lamp miniaturized via one or multiple bends, that provides high lumen package in compact size.    Mostly used in downlights.        More...
comparison – T.C.O. total Cost of Ownership comparison report produced to evaluate the economical feasibility of two or more alternative lighting systems
connector - feed end-piece track lighting part designed to connect track lighting system to external power
connector - L track connector designed to connect electrically and mechanically two pieces of track installed under 90 degree angle
connector - mini joiner shortest available, miniature plastic connector designed to connect together mechanically and electrically two pieces of track
connector - straight track connector designed to connect mechanically and electrically two pieces of track. This connector is also suitable to be used as a 2-circuit feed point
connector – T track connector designed to connect electrically and mechanically three pieces of track installed under 90 degree angle
connector – X track connector designed to connect electrically and mechanically four pieces of track installed under 90 degree angle
contactor electro-mechanical device designed to control multiple lighting circuits with one conveniently located main switch.         More…
contractor a company or individual with a formal contract to do a specific job, supplying labor and materials and providing and overseeing staff if needed
core-and-coil ballast magnetic ballast system consisting of several separate parts, i.e. coil and capacitor, that must be installed in separate, approved enclosure.   Used with metal halide or high pressure sodium lamps
cove lighting lighting system comprising lamps or other light sources shielded by a ledge or horizontal recess.
daylighting    Daylighting optimizes natural sunlight entry into a building to minimize the need for artificial lighting. A method of filling a room with well-diffused natural sunlight.
DC lighting recently introduced commercial lighting system designed to significantly extend the useful life of halogen MR16 and PAR lamps by powering them with regulated direct-current (DC) power, with no voltage spikes, fluctuations or surges.        More...  
decorative lighting fixture accent lighting luminaire that makes a decorative statement not only when it is turned on but also when it is turned off
diffused lighting lighting that arrives reflected from, or scattered by diffuser
diffuser a surface or translucent material to redirect or scatter reflected or transmitted light.   A white wall is an example of a surface diffuser
dimmer an electronic device designed to regulate light output of incandescent and halogen lamps; and fluorescent lamps in fixtures equipped with special dimming ballasts
direct light the portion of the light from a luminaire which arrives at the work-plane without being reflected by room surfaces
direct-indirect luminaire light fixture specially designed to increase visual comfort by producing a balanced combination of direct and indirect light
discharge lamp a lamp that uses electric discharge inside of gas chamber, to convert electricity to lighting.   Included are groups of lamps known as fluorescent, metal halide, and high pressure sodium
double-ended lamp typically metal halide or halogen, linear-shaped lamp with one contact on each end. Base code: RX7s.    Used in flood lights, wall washers and lighting effects
double-parabolic louver optical glare controlling element that uses parabolic reflective surfaces in both directions, or two separately curved parabolic reflectors in the same direction
downlight recessed or surface mounted luminaire with light output directed downwards
drywall ceiling permanently enclosed, solid plaster ceiling. Plenum is accessible only through fixture opening(s) or specially installed access doors or panels
drywall kit special hardware kit (frame) deigned to allow installation of T-bar designed fluorescent fixtures, in the drywall ceilings
Duro-Trans large size slide / transparency with graphic / visual expression, installed on a back-lit surface for attention-grabbing effect. Best results are achieved when transparencies are illuminated with “daylight” lamps with color temperature of 5000 Kelvin or more
efficacy the ratio of lumens produced by a lamp to the watts consumed, expressed as lumens per watt (LPW). The higher the lumens per watt, the more efficient the lamp
efficiency the ratio of total light output measured in lumens emitted by a luminaire to that emitted by the lamp or all lamps used therein
efficient lighting energy efficient lighting is the use of artificial light to provide the optimal level of light for the lowest energy investment. However, energy efficient lighting is not simply finding the most light for the least wattage or the longest lasting light bulb. Proper sizing of the light to the needs of the location and the tasks that will be performed, called task lighting, is also very important part of energy efficient lighting
egg-crate louver an inexpensive white plastic or metalized plastic panel with square cell openings, frequently used to reduce glare of recessed troffer fluorescent fixtures
electronic ballast high efficiency ballast that uses electronic circuitry to provide proper starting and operating electrical conditions for discharge lamp, or multiple lamps
emergency lighting lighting system designed to provide minimum illumination required for safety, during power failures.   Draws energy from batteries or generator, or combination of both
energy audit detailed analysis and report outlining lighting system’s energy consumption and operating costs
energy consumption value registered and metered by the utility company, to charge customers for energy usage.    Electrical energy consumption is in kilowatt-hours
energy efficient energy efficient lighting is the use of artificial light to provide the optimal level of light for the lowest energy investment.     However, energy efficient lighting is not simply finding the most light for the least wattage or the longest lasting light bulb.   Proper sizing of the light to the needs of the location and the tasks that will be performed, called task lighting, is also very important part of energy efficient lighting
extension wand track lighting accessory consisting of thin hollow pipe and track adapters on each end, wired together.    Installed between track and track fixtures, extension wands are used to suspend track fixtures to lover position
F-can ballast fully encapsulated ballast ready to be installed in the building without a need of any additional enclosure
feed connector end-piece track lighting part designed to connect external power to track lighting system
fiber optic lighting lighting system consisting of one or multiple, remotely installed light source(s); and light distribution “pipes” or fibber optic cables that carry light to locations of it’s final use. Fiber optic cables can be side glowing for linear special effects or end-glowing for task lighting or spotlighting effects.       More...
filament a piece of wolfram wire inside of incandescent or halogen lamp. When heated by electricity, filament glows white and produces light
filters made from colored or UV-blocking glass, filters are accessory to track lighting or downlights used when special (theatrical) color effects or complete elimination of UV radiation are required
fixture spacing distance between luminaries, or area covered by each luminaire, needed to achieve desired light levels
flexible gooseneck specialty light fixture designed to be easily field-adjustable, allowing full flexibility of aiming.   Flexible gooseneck is typically 24 – 36 inch long and for weight reasons, fixture is usually miniature head with MR16 or MR11 halogen lamp
flood light lighting fixture or lamp with wide beam distribution, typ. 38 - 45 degrees
fluorescent lamp a low-pressure electric-discharge lamp in which a fluorescent coating transforms some of the ultraviolet energy generated by electric discharge, into light.       More…
fluorescent phosphors the color of fluorescent lamps is created by mineral phosphors in powder form which coat the inside of the lamp tube. The chemical make-up of these phosphors determines the lamps CRI, its Color Temperature, and how much light the lamp produces
foot-candle it is the illuminance on one square foot area on which there is a uniformly distributed flux of one lumen  
gimbal ring track fixture or downlight designed to hold halogen PAR or MR16 lamp in round open ring, adjustable both vertically and horizontally
glare glare is the action of light exiting the lamp (light bulb) and directly entering the observer's eye.   Glare can be useful or a hindrance
glare control optical fixture elements designed to reduce or eliminate glare.   Included are baffles on downlights and louvers on fluorescent fixtures
glass lens protective glass piece installed in the fixture’s aperture, to protect people and surroundings from flying pieces of hot glass in case of destructive breakdown of the lamp.   Commonly used with “enclosed fixture” rated metal halide and halogen lamps
glass refractor bell-shaped optical system made from glass, similar to reflector, but designed to redirect small portion of lamp’s light output upwards and around the fixture, to create some level of indirect lighting or brighter perception of illuminated area
gooseneck fixture specialty light fixture designed to be easily field-adjustable, allowing full flexibility of aiming.    Flexible or rigid gooseneck is typically 24 – 36 inch long and for weight reasons, fixture is usually miniature head with MR16 or MR11 halogen lamp
group relamping replacement of all lamps at about 60 – 80% of expected lamp life.   All fixtures are cleaned at the same time.   Most cost effective maintenance method.  Opposite to spot relamping, replacement of one lamp at the time as the old lamps burn out.    More…
H.I.D.    lamp "High Intensity Discharge" -- a lamp that uses electric discharge inside of pressurized gas chamber, to convert electricity to lighting. Included are groups of lamps known as mercury, metal halide, and high pressure sodium
H.Q.I.   lamp special metal halide lamp available in 70 Watts and 150 Watts, single-ended or double-ended, mostly used in European-originated commercial luminaries
high bay fixture reflector-shaped industrial luminaire, typically with metal halide lamp, designed to illuminate from installation heights of 12 feet and up
high performance lighting a lighting system or luminaire that uses high efficacy (80 or better), high color rendering (80 or better) light sources in combination with efficient optical systems (i.e. reflectors) that provide high (75 or more) Coefficient of Utilization (CU)
housing frame and in-ceiling electrical part of recessed fixture
housing insulated frame and in-ceiling electrical part of recessed fixture, used in insulation-covered ceiling systems
housing new construction frame and in-ceiling electrical part of recessed fixture, designed to be installed before final ceiling panels are installed
housing remodel frame and in-ceiling electrical part of recessed fixture, designed to be installed after ceiling panels are installed, i.e. in existing ceilings
Incandescent lamp A light source which generates light using a thin filament wire (usually tungsten) heated to white heat by an electric current passing through it.
Illuminance, E Unit: Lux, 1x
The ratio of luminous flux and emitted area.1 LUX’s illuminamce is the luminous flux indicate on a unit area symmetrically.
indirect light the portion of the luminary’s light output arriving at the work-plane after being reflected by room surfaces, or specially designed luminaire surfaces (white reflectors or diffusers)
instant start fluorescent lamp / ballasts system where no lamp preheat circuits are required. Lamp is started by application of high voltage pulse. Only two wires are used to connect lamp to ballast
Integrating sphere A hollow sphere coated internally with a white diffusing material and provided with openings for incident beam, specimen and detector used for measuring the diffuse reflectance or transmittance of objects.
K12  lens most commonly used flat plastic panel with specific standardized “K12” pattern, installed in the fixture to visually cover the lamps, and to lower glare by redirecting or diffusing lamp’s light output
kilowatt one thousand watts.   Watt: the international unit of power equal to the power produced by a current of one ampere acting across a potential difference of one volt
kilowatt-hour the amount of electric energy consumed by power load of one kilowatt, in one hour
L.L.F. "Light Loss Factor" -- a factor used in calculating light levels maintained after a given period of time and under specified conditions. It takes into account the dirt accumulation on luminaries and room surfaces, lamp depreciation, maintenance procedures and atmospheric conditions
lamp a man-made device that changes electricity to light, also called a “bulb” for incandescent lamps or “tube” for fluorescent lamps
lamp - extended life technologically improved fluorescent, halogen or incandescent lamp specially designed to deliver highest possible lamp life to reduce maintenance costs and annoyance associated with hard-to-reach areas. Available with up to 30,000 hours (6 years) lamp life expectancy
lamp A19 the shape and size of common household incandescent light bulb available in 40 Watts, 60 Watts and 100 Watts.    Clear or frosted white
lamp beam –wide flood creates 42 - 50 degree wide beam area with lowest target light levels. Typically used in MR16 showcase display lighting and other applications where lamp must illuminate wide area, from very short distance.       More…
lamp beam –flood creates 32 – 36 degree wide beam area with low target light levels. Typically used in downlights for low level (residential) ambient lighting.      More…
lamp beam - narrow flood creates 22 – 26 degree wide coverage area with medium target light levels. Most commonly specified MR16 lamp in track lighting fixtures, will provide good accent light effect in galleries and retail displays, with track installed 9 – 10 ft above the floor, 30 – 36” from the wall.      More...
lamp beam – spot creates 12 – 14 degree narrow beam with high target light levels. Typically used for accent lighting in track lighting fixtures.     More…
lamp beam - narrow spot creates 9 – 11 degree, very narrow beam with higher target light levels. Typically used for accent lighting from larger distances.      More…
lamp beam - very narrow spot creates 5.5 – 7 degree, sharply narrow beam with highest target light levels. Available in low voltage PAR36 lamps only. Excellent for sharp accent lighting from larger distances or special effects.       More…
lamp Biax same as PLL lamp by Phillips or Dulux-L by Osram. 12 – 21 inch long, high-lumen T5 single-ended compact fluorescent lamp. Premium lumen package up to 4800 lm / 55W lamp.    Biax is GE Lighting brand.         More…
lamp bi-pin sub-miniature low voltage halogen lamp typically 12V / 5 – 10 – 20 Watts used in miniature “puck” lights, showcase lighting and some decorative pendant fixtures
lamp Capsylite Sylvania’s brand of halogen PAR16, PAR20, PAR30 and PAR38 lamps
lamp compact fluorescent single-ended fluorescent lamp miniaturized via one or multiple bends, that provides high lumen package in a compact size.    Mostly used in downlights
lamp discharge a lamp that uses electric discharge inside of gas chamber, to convert electricity to lighting.   Included are groups of lamps known as mercury, metal halide, and high pressure sodium
lamp double-ended typically metal halide or halogen, linear-shaped lamp with one contact on each end. Base code: RX7s.     Used in floodlights, wall washers and lighting effects
lamp fluorescent a low-pressure electric-discharge linear lamp, a coated tube in which a fluorescent coating transforms some of the ultraviolet energy generated by electric discharge, into light.       More…
lamp halogen a gas filled tungsten incandescent lamp containing proportion halogens in an insert gas whose pressure exceeds three atmospheres
lamp high pressure sodium high intensity discharge (HID) lamp in which light is produced by radiation from sodium vapor operating at a partial pressure of about 1.33 x 104 Pa (100 torr). Includes clear and diffuse coating
lamp  HQI special metal halide lamp available in 70 Watts and 150 Watts, single-ended or double-ended, mostly used in European-originated commercial luminaries
lamp incandescent a lamp in which light is produced by a filament (wolfram wire) heated to incandescence by an electric current
lamp life is value estimated, but not guaranteed, by lamp manufacturer, in hours.   It is defined as a period of time, in which 50% of a given sample batch of lamps will be burned out, and 50% will be still surviving.   Lamp life is affected by many different conditions, but mainly by power quality of supply line.     More…
lamp line voltage lamps that operate on direct connection to line power supply voltage 120 Volts
lamp low voltage lamps that operate at 12 Volts or 24 Volts.  These lamps require a transformer, magnetic (cheaper but heavier) or electronic (smaller), to reduce the line voltage to lamp’s voltage
lamp Mastercolor ceramic metal halide lamp brand made by Philips Lighting.   Premium color rendering and color consistency.  Available in PAR30, PAR38, single-ended and double-ended enclosures.      More…
lamp metal halide a high intensity discharge (HID) lamp in which the major portion of the light is produced by radiation of metal halides and their products of dissociation. Includes clear and phosphor coated lamps. More…
lamp   MR11 35 mm diameter, smallest available reflector halogen lamp, low voltage 12 Volt or 24 Volt, with bi-pin base code GX 5.3. 20 – 35W max. Mainly used in specialized task lighting. i.e. showcases and retail displays.      More...  
lamp   MR16 51 mm diameter, miniature reflector halogen lamp, low voltage 12 Volt or 24 Volt, 20 – 75W max. with bi-pin base code GX 5.3.     More…
lamp    MR16 - Constant Color General Electric special design and brand of MR16 lamp that is known to have longest lasting service (lamp life) and good maintenance of bright white light output.   Light output from some other MR16 lamps might turn yellowish or greenish after few weeks or few months of operation
lamp MR16 - enclosed MR16 lamp that has a permanently attached protective glass lens. Most common MR16 lamp specified in commercial lighting projects
lamp  MR16 - open open design MR16 lamp that requires an additional glass lens to be inserted into the fixture when lamp is being installed.    Open MR16 lamps are not allowed to operate without proper glass shield due to fire hazard and/or health hazard caused by flying hot pieces of glass in case of destructive breakdown of the lamp
lamp  PAR "Parabolic Aluminized Reflector" lamp that has internal reflective coatings which, in combination with various filament locations and lenticular patterns on the bulb face, achieve a variety of light distribution patterns. Commonly specified sizes are PAR16, PAR20, PAR30, PAR38, PAR36, PAR56 and PAR64. Average rated life is 2,000 hours. Get the diameter (in inches) of any PAR lamp by simply dividing the PAR number by 8. More…
lamp  PAR16 2” diameter, screw-in, medium base line voltage PAR lamp, 20 – 50 Watts max. Used in special task lighting applications.     More…
lamp PAR20 2-1/2” diameter, screw-in, medium base line voltage PAR lamp, 20 – 50 Watts max. Used mainly in low budget residential installations. Note: 50 Watt PAR20 lamp has only about half light output of 50 Watt MR16 lamp and more yellow color.    More…
lamp  PAR30 3-3/4” diameter, screw-in, medium base line voltage PAR lamp, 50 – 75 Watts max. Used mainly in retail store and showroom track lighting systems. Note: 75 Watt PAR30 lamp has about the same light output as 50 Watt MR16 lamp.     More…
lamp  PAR36 4-1/2”, low voltage PAR lamp 6 Watts – 100 Watts max. Screw terminal base G5.3. Used mainly in accent display lighting when very narrow spot, high intensity beam is required.    More...
lamp  PAR38 4-7/8” diameter, screw-in, medium base line voltage PAR lamp, 45 – 120 Watts, used mainly for general lighting in downlights, and in track lighting in retail stores, showrooms and galleries.    More…
lamp  PAR56 7” line voltage PAR lamp up to 500 Watts max, used mainly in entertainment lighting, underwater pool lighting or special effect lighting
lamp  PAR64 8” line voltage PAR lamp up to 1000 Watts max, used mainly in entertainment stage productions
lamp  PL low wattage, 5-7-9-13 Watts, short compact T4 fluorescent lamp. The least expensive, very common lamp. 800 lm max / 6.2” overall length.     More…
lamp  PLC double-legged, high lumen T4 compact fluorescent lamp, typically 13, 18 or 26 Watts. Provides good lumen package (1,800 lm max.) in compact (6.5”) overall lamp dimension. Typically used in recessed downlights.     More…
lamp  PLL same as Biax lamp, 12 – 21 inch long, high-lumen T5 single-ended compact fluorescent lamp.   Premium lumen package up to 4800 lm / 55 Watts lamp. Biax is brand of GE Lighting.     More…
lamp  PLQ triple-legged, high lumen compact T4 fluorescent lamp, typically 18, 26, 32 or 42 Watts. Provides premium lumen package (3200 lm max.) in compact overall lamp (6.3”) dimension. Typically used in recessed downlights and track lighting wall washers. More…
lamp  R30,  R40 obsolete technology, inefficient incandescent light bulb with outer envelope shaped in the form of metalized reflector.    Outlawed for commercial use in USA and Canada due to poor efficiency.    Replaced by PAR30 and PAR38 halogen lamps
lamp replacement removal of burned out lamp and reinstallation of new lamp. Using replacement lamp with exactly same parameters / cat. number as original lamp is highly recommended. Especially with fluorescent and H.I.D lamps where correct, accurate match between the ballast and the lamp is very important
lamp  T2 7 mm diameter.    Pencil-thin fluorescent lamp, available in wattages and lengths 6W / 8.6” to 13W / 20.6”. Used in specialized task lighting and accent lighting applications, i.e. retail displays, showcases, step lights and emergency lighting systems. Good efficacy and CRI around 80
lamp  T5 16 mm diameter.   Latest introduction to high performance fluorescent lighting systems. Excellent efficacy of 100+ lumens / Watt. Available in sizes up to 5 ft, 80 Watts / 7000 lumens per lamp
lamp  T8 26 mm diameter.   Most commonly specified fluorescent lamp. Good system efficacy and CRI of 75 (700 series), 85 (800 series) or 95 (900 series). Common 48” T8 lamps are inexpensive and readily available
lamp  T10 32 mm diameter.   High performance fluorescent lamp designed to work with older magnetic ballasts, specially in retrofit projects where higher light levels or reduced lighting loads (delamping from 4 lamps to two lamps with reflector) are required. Only available in 48” lengths, 40 Watt design that produces 3,650 initial lumens and a very good CRI of 85.   Available from Philips Lighting and Panasonic Lighting
lamp  T12 38 mm diameter.    Older technology fluorescent lamps. Today almost obsolete and used for replacement in existing older fixtures only. Low efficacy and poor Color Rendering Index (CRI) of only about 65
layered lighting a lighting system that simultaneously uses multiple different lighting techniques to achieve desired results.    A good example is well-designed auditorium lighting where direct PAR38 downlights provide proper light levels for writing and reading tasks, indirect ceiling luminaries eliminate shadows, and perimeter indirect lighting wall sconces improve overall perception of room’s brightness and visual comfort probability (VCP)
lay-in fixture luminaire designed for installation in T-bar ceilings
lead time time required by lighting manufacturer to deliver the order, from the date of receiving the purchase order
LED (light-emitting diode) A PN junction device that gives off light radiation when biased in the forward direction.
lens flat plastic panel installed in the fixture to visually cover the lamps, and to lower glare by redirecting or diffusing lamp’s light output
lens  K12 most commonly used flat plastic panel with specific standardized “K12” pattern, installed in the fixture to visually cover the lamps, and to lower glare by redirecting or diffusing lamp’s light output
Light and radiation The light is mean the human eyes can sense the bright electromagnetic radiation. The human visual range is typically from 360nm to 830nm.
Light Color 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 will be given off by the lamp.
The most typical Kelvin degree lamps used in lighting are as follows:
Kelvin
Associated Effects & Moods
Appropriate Applications

2700
°
Friendly, Personall, Intimate
Homes, Libraries, Restaurants

3500
°
Friendly, Inviting, Non-threatening
New Offices, Public Reception areas

4100
°
Neat, Clean, Efficient
Older offices, Classrooms, Mass Merchandisers

5000
°
Bright, Alert, Exacting Coloration
Graphics, Jewelry Stores, Medical Exam Areas

In the LED area, we usually describe the white light which below 5000K as the incandescent light source, 5000-8000K as the warm light source, above 8000K as the cool light source. The scale ranges from 1(low pressure sodium) to 100(the sun). The higher the CR (based upon a 0-100scale), the better colors appear.
light level calculations a mathematical method to determine maintained light levels, based on parameters of space and luminaire characteristics.      More…
light levels
light loss factor (L.L.F.) a factor used in calculating maintaining light levels after a given period of time and under specified conditions. It takes into account the dirt accumulation on luminaries and room surfaces, lamp depreciation, maintenance procedures and atmospheric conditions
light pipe recently developed technology consisting of single powerful light source typically 1,000 Watts or more, and special light distribution “pipe” developed by 3M that illuminates surrounding areas by brightly glowing along it’s entire length.     More… http://www.thelightingcenter.com/3m/3mlightpipe.asp
lighting - high performance a lighting system or luminaire that uses high efficacy (80 or better), high color rendering (80 or better) light sources in combination with efficient optical systems (i.e. reflectors) that provide high (75 or more) Coefficient of Utilization (CU).      More…
lighting circuits electrical distribution circuits dedicated to powering light fixtures
lighting load power used by all luminaries in given area, usually expressed in watts per square foot
lighting maintenance regular or irregular replacement of burned out lamps, defective ballasts etc. Included should be fixture cleaning in regular intervals (every 2 – 4 years), to eliminate lumen depreciation due to dirt accumulation
lighting software computer program that will calculate light levels and/or provide full point-by-point light level report
line voltage lighting lighting system that uses line voltage lamps 120 Volts connected directly to power supply line
linear lighting lighting system that contains a number of in-row configured luminaries or light sources, i.e. rope lighting, Brite- strip or side glowing fiber optic lighting
louver plastic or metallic optical cell system, designed to improve glare control, performance, efficiency or architectural appearance.      Frequently combined with reflectors in well-designed, high performance commercial fluorescent luminaries
low bay fixture reflector-shaped industrial luminaire with bottom diffuser, designed to illuminate from low ceilings 8 to 12 feet high
low voltage lighting lighting systems that uses safe 12 Volt or 24 Volt lamps. Needs lighting transformer to convert power supply line voltage to low voltage.        More…
lumen International System unit that determines light output emitted within a unit of solid angle (one steradian) by a point source having a uniform luminous intensity of one candela
lumen depreciation loss of lamp’s initial light output due to aging
Luminaire Efficiency The ratio of total lumens emitted by a luminaire to those emitted by the lamp or lamps used.
Luminous flux Unit: Lumen, lm
Defined as the total luminous energy per unit time emitted by the light source into a sphere(360°)surrounding the light source, where the luminous flux multiplied by the human eyes sensitivity. The measurement unit for luminous flux is the lumen (lm).
Luminous Intensity (lv) Unit: candela, cd
The amount of luminous flux emitted into a very small solid angle at a defined angular orientation from the light source. The unit of luminous intensity is the lumen/steradian (lm/sr), or candela (cd). Generally, light source will emit its luminous flux at different of direction of different luminous intensity.
Luminous intensity is the visible light, which emit at a defined angular orientation.
Luminance (LV) Unit:cd/㎡
Luminous flux per unit solid angle per area of emitting surface at an angle with respect to surface normal, in candela per square meter or nits.
Important formulae of light measurement:
I: luminous intensity﹤cd﹥=total light energy in tridimensional angel/tridimensional angle Ω﹤sr﹥
E:Illuminance ﹤lx﹥=the luminous flux indicate on a unit area symmetrically ﹤lm﹥,unit area of emitting surface﹤㎡﹥=Luminous intensity﹤cd﹥﹤distance﹥﹤㎡﹥
IV:Luminance ﹤cd/㎡﹥=Luminous intensity﹤cd﹥/Unit area of emitting surface of sight﹤㎡﹥
:Luminous Efficacy﹤lm/w﹥=total output of luminous flux﹤lm﹥dissipated wattage﹤㎡﹥
Luminous Efficacy Unit: lm/W
The light output of a light source divided by the total power input to that source. It is expressed in lumens per watt.
master & slave cost-saving configuration of row-installed fluorescent fixtures with single ballast in every second (master) fixture powering thelamps in both master fixture and slave fixture
Mastercolor Philips Lighting brand of ceramic metal halide lamp.     Premium color rendering and color consistency
medium base standard lamp base on all common light bulbs. Base code: E26 or E27
metal halide lamp a high intensity discharge (HID) lamp in which the major portion of the light is produced by radiation of metal halides and their products of dissociation. Includes clear and coated lamps
mini joiner shortest available, miniature connector joining together two pieces of track
minigimbal mompact size track lighting fixture; or downlight gimbal ring fixture used with MR16 or MR11 lamps
mogul base large size lamp base used in industrial luminaries, mostly with high intensity discharge (H.I.D.) lamps. Base code: E39 or E40
moisture proof fluorescent fixture with special gasketed enclosure approved to be used in wet areas, i.e. cooking area or car wash
monopoint simple plastic, round- or square-shaped junction box cover designed to provide mechanical mounting and electrical connections for one track lighting fixture
narrow spot provides typically 9 – 11 degrees, very narrow beam with higher target light levels. Typically used for accent lighting from larger distances.      More…
open concept ceiling ceiling-less interior design.    Roof rafters or support structure above and all wiring, piping, ducts and other infrastructure are exposed. Usually much more expensive than enclosed ceiling systems with all infrastructure hidden in the plenum
open rated lamp metal halide lamp that has a special protective shield built right inside of outer enclosure, to protect people and surrounding areas from flying pieces of hot glass in case of destructive breakdown of the lamp.   Open rated lamp will fit in both “open rated” and “closed rated” luminaries.
open rated luminaire commercial fixture that uses H.I.D. lamps (metal halide or high pressure sodium) that is designed to accept “open rated lamps” only,   by special feature of the lamp’s socket
optical system mechanical elements of luminaire designed to focus, direct, redirect, diffuse or scatter lamp’s light output, in order to achieve required performance and characteristics
PAR  lamp "Parabolic Aluminized Reflector" -- lamp that has internal reflective coatings which, in combination with various filament locations and lenticular patterns on the bulb face, achieve a variety of light distribution patterns.   Commonly specified sizes are PAR16, PAR20, PAR30, PAR38, PAR36, PAR56 and PAR64. Average rated life is 2,000 hours. Get the diameter (in inches) of any PAR lamp by simply dividing the PAR number by 8. More…
path lighting lighting system designed to illuminate or visually identify walking path or sidewalk
pendant fixture cable-suspended luminaire
perception of brightness subjective perception of light intensity as received by human eye.   It is affected by overall balance of different elements: brightness of walls, floors and ceiling, light levels throughout the space, and relative brightness of surrounding environments.    More…
perimeter lighting lighting system designed to illuminate perimeter walls or areas
photometric report luminaire performance and characteristics report and electronic file, created upon completion of physical testing of luminaire on special laboratory equipment
pipe lighting recently developed technology consisting of single powerful light source typically 1,000 Watts or more, and special light distribution “pipe” developed by 3M that illuminates surrounding areas by brightly glowing along it’s entire length.    More… http://www.thelightingcenter.com/3m/3mlightpipe.asp
PL   lamp low wattage, 5-7-9-13 Watts, short compact T4 fluorescent lamp. The least expensive, very common lamp. 800 lm max / 6.2” overall length.      More…
PLC  lamp double-legged, high lumen T4 compact fluorescent lamp, typically 13, 18 or 26 Watts. Provides good lumen package (1,800 lm max.) in compact (6.5”) overall lamp dimension. Typically used in recessed downlights.      More…
PLL  lamp same as Biax lamp, 12 – 24 inch long, high-lumen compact fluorescent lamp. Biax is GE Lighting brand
PLQ  lamp triple-legged, high lumen compact T4 fluorescent lamp, typically 18, 26, 32 or 42 Watts. Provides premium lumen package (3200 lm max.) in compact overall lamp (6.3”) dimension. Typically used in recessed downlights and track lighting wall washers. More…
plenum hollow space between ceiling panel (drywall, T-bar tile or metal / wood panel) and roofing panels, or other hollow space meant to accommodate light fixtures and wiring
pole lighting exterior lighting fixtures installed on concrete, steel, aluminum or lately, fiberglass poles. Typical for street lighting and for parking lot, sidewalk and park pathway lighting
polycarbonate durable, virtually unbreakable plastic material, transparent clear, translucent or opal white, used to manufacture unbreakable, i.e. vandal-resistant luminaries
pot light common word for recessed downlight.
protective lens plastic or glass panel installed in the fixture’s aperture, to protect people and surroundings from flying pieces of hot glass in case of destructive breakdown of the lamp. Commonly used with “enclosed fixture” rated metal halide and halogen lamps
pulse start system recently introduced high efficacy (100 lumens / Watt) metal halide lamp + ballast system. Lamp is started by high voltage pulse. Lamp socket must be “pulse rated” with minimum pulse rating of 4000 Volts.      More…
quartz lamp common name for tungsten halogen lamp
R. C. R. "Room Cavity Ratio" -- A number indicating cavity proportions from length, width, and height. This value used in the coefficient of utilization calculation for a given luminaire in a space with specified room reflectance and dimensions
rapid start a fluorescent lamp designed for operation with a ballast that provides a low-voltage winding for preheating the electrodes and initiating the arc without a starting switch or the application of high voltage. Four wires are required to connect lamp with the ballast
recessed fixture entire fixture is fully concealed within the ceiling, with opening (aperture) flush mounted with the ceiling
reflectance - ceiling  fractional number describing amount of light reflected by ceiling’s surface. White ceiling has reflectance of 1, matte black ceiling close to zero
reflectance - floor fractional number describing amount of light reflected by floor’s surface. Light colored floor has reflectance close to 1, dark matte floor close to zero
reflectance - walls fractional number describing amount of light reflected by wall’s surface. White wall has reflectance of 1, mat black wall close to zero
reflector optical system typically made of aluminum, designed to direct and/or focus lamp’s light output in one specific direction
refractor reflector-shaped optical system made from acrylic or polycarbonate plastic, or glass; designed to redirect small portion of lamp’s light output upwards and around the fixture, to create some level of indirect lighting and brighter perception of illuminated area
relamping "Group Relamping" -– replacement of all lamps at about 60 – 80% of expected life span. All fixtures are cleaned at the same time. Most cost effective maintenance method. Opposite is spot relamping, replacement of one lamp at the time, as old lamps burn out.     More…
remote ballast ballast that is installed remotely from the fixture. Typical for architectural pendant luminaries where ballast is hidden in the ceiling system. Maximum allowed distance between ballast and luminaire is usually limited to 12 feet.     More…
retrofit kit a combination of new high efficiency lamp, ballast and/or reflector/louver, designed to improve the efficiency and/or performance and/or aesthetics of existing luminaire, without the cost of replacing the entire fixture
retrofit lamp high efficiency lamp designed to produce significant energy savings, without compromising light levels, suitable to operate on fixture’s existing ballast
retrofit louver plastic or metallic panel with optical cells, designed to improve existing fixture’s look, glare control, performance or efficiency
room cavity ratio "Room Cavity Ratio" A number indicating cavity proportions from length, width, and height. This value used in the coefficient of utilization calculation for a given luminaire in a space with specified room reflectance and dimensions
rope lighting flexible linear light fixture in form of long transparent or colored plastic tube filled with miniature long life incandescent lamps wired together. Used for special effects and exterior applications, i.e. as outline of buildings
safety cable a loop of aircraft cable installed around the fixture’s console and the above track. Designed to provide additional safety measure to heavy track lighting luminaries, i.e. metal halide fixtures with magnetic ballast
safety chain a chain attached between recessed luminaire and main building structure, designed to prevent luminaire from falling in case of ceiling breakdown
security lighting low energy lighting designed to provide minimum visibility required to secure buildings or objects
shatterproof fluorescent or incandescent lamps equipped with transparent silicone coating that will hold all pieces of glass together in case of lamp breakage. Used in food preparation areas
showcase lighting lighting system designed to illuminate showcase displays.    Included are miniature low voltage track systems and linear low voltage systems i.e. Brite-strip
slave fixture empty fluorescent fixture with no ballast, lamp is powered by remote ballast (due to space restrictions) or by ballast in nearby master fixture -- see master-slave configuration
socket lamp holder, made from porcelain for incandescent and HID lamps or from plastic for fluorescent lamps. Recent introduction of polycarbonate fluorescent lamp holders eliminated socket breakdowns and dramatically reduced servicing costs of fluorescent luminaries
spacing distance between luminaries, or area covered by each luminaire, needed to achieve desired light levels
Spectrum Line spectra was distributed according to the wavelength from big to small. The spectrum of sun light and incandescent solids are said to be continuous because all wavelengths are present. The spectrum of incandescent gases, on the other hand, is called a line or emission spectrum because only a few wavelengths are emitted. These wavelengths appear to be a series of parallel lines because a slit is used as the light-imaging device.
spot light narrow beam, focused light
staggered strip fixture a double-lamp strip fixture for row mounting with overlapping ends.  Specially designed for cove or back lighting applications to eliminate dark spots where fixtures are connected together
strip fixture inexpensive linear fluorescent fixture consisting of basic fixture body, ballast, lamp holders and lamp.   It has no optical system, lamp’s output is simply radiated into the surrounding space
styrene lens flat plastic panel made from styrene, installed in the fixture to visually cover the lamps, and to lower glare by redirecting or diffusing lamp’s light output.    Warning: Styrene material is subject to fast aging and yellowing when used in fluorescent luminaries
surface fixtures luminaire installed on the ceiling’s level, attached directly to the ceiling.   Needs only pre-wired junction box to be installed
surface mounting trim accessory to fluorescent fixture: A decorative trim that allows lay-in fluorescent fixture (designed for T-bar ceilings) to be used as a surface mounted, or suspended luminaire
suspended fixtures luminaries installed lower than ceiling level, suspended by chain, pipe conduit, cable, or aircraft cable
suspension - aircraft cable fixture or track lighting suspended on thin steel wire of properly rated strength, barely visible when installation is completed.       More…
suspension kit kit provided by fixture manufacturer, consisting of suspension chain, cable or aircraft cable and all brackets and hardware necessary to complete the fixture installation
system efficiency the ratio of total light output measured in lumens emitted by a luminaire to that emitted by the lamp or all lamps used therein
task lighting task lighting serves a limited area where a person's work or other activity that needs illumination, is concentrated
T-bar ceiling enclosed ceiling system consisting of permanently installed “inverted T” frame with openings filled with light weight acoustical ceiling panels. Most commonly used in commercial projects, T-bar ceiling provides the easiest access for installation or servicing of light fixtures.     More…
time counter a non-resetable time registering device connected to the control circuit of lighting contactor, to register total usage hours on the lamps. A very simple, inexpensive device that helps to determine correct time for cost-effective Group Relamping.    More…
total cost of ownership total amount of money spent by the end user to acquire, install, operate and maintain the lighting system over a specific period of time, usually five years or ten years
track 2-wire system track lighting system that has only two copper wires inside of track’s extrusion to distribute power to fixtures:  Live wire and neutral.   Safety grounding is provided by track extrusion and it’s direct contact with track fixtures and other electrical elements of the system.  Having certain safety limitations, 2-wire systems are usually used in residential installations
track 3-wire system track lighting system that has three heavy duty copper bars inside of track’s extrusion to distribute power to fixtures:  Live wire, neutral and a dedicated ground connection that is reliably and consistently connected with track fixtures and other electrical elements of the system
track adapter track lighting component that allows fixture to be installed on the track.  Track adapter must be always compatible with the track
track compatibility different manufacturers offer different track systems that are usually not compatible with each other.    To work on the track, track fixtures must be compatible with track lighting system
track extension wand a track lighting accessory consisting of thin hollow pipe and track adapters on each end, wired together.   Installed between track and track fixtures, extension wands are used to suspend track fixtures to lover position
track extrusion the body of lighting track is usually made of aluminum extrusion with special inside grooves that accommodate power distributing copper bars installed in plastic insulators
track fixtures luminaries designed to be installed on the lighting track
track lighting modern lighting system that provides flexible and movable mechanical and electrical connection of luminaries anywhere along the pre-installed lighting track 
track lighting setback the distance between the track and the wall or front of the display to be illuminated.  In most instances, a setback of 30 – 36 inches will work fine on 8 – 10 ft. ceiling installations, with little shadows.    More...
track suspension kit a kit provided by track manufacturer, consisting of suspension pipes, mounting canopy, brackets and all other hardware necessary to complete the suspended track installation
transformer - lighting an electric or electronic device converting power supply voltage of 120 Volts to 12 Volt or 24 Volt safe low voltage output, to power low voltage lamps
trim part of the downlight luminaire visible from the room, mounted flush with the ceiling. The last part of the light fixture installed when ceiling is completely finished
trim – adjustable trim that allows adjustment of lamp’s direction by tilting (30 degrees or more) and/or rotating (355 degrees) of lamp’s holder.    Most commonly specified with MR16 halogen lamps in directional accent/display lighting or task lighting
trim – baffle trim that uses grooved, deep cylindrical insert to shield light source from direct view of an observer at certain angles.   Finished in flat black or flat white
trim - cross blade trim that uses polished aluminum or white louver to reduce or eliminate glare.  Usually specified with compact fluorescent downlights
trim - pin hole smallest aperture trim specified where light fixtures must make minimum necessary visual statement.    Specified with spot or narrow spot MR16 lamps
trim – tilting trim that allows adjustment of lamp’s direction by tilting lamp 30 degrees or more. Commonly specified with MR16 halogen lamps in directional accent/display lighting or task lighting
troffer simple recessed fluorescent luminaire, a white box with lamps and ballast.    Lamps are normally covered with plastic lens or plastic or metallic louver.
UV   filter accessory to downlight or track lighting fixture.  A lens made from special UV-absorbing glass.   Specified where UV contents of visible artificial light must be completely eliminated, i.e. art galleries and apparel stores
vandal resistant unbreakable luminaire designed for public areas prone to vandalism, i.e. subway
very narrow spot special low voltage halogen lamp (PAR36) that provides sharply focused, very narrow beam 5.5 – 7 degrees wide.   Used for pinpoint sharp lighting spots or for accent lighting from large distances
visual comfort probability the rating of a lighting system expressed as a per cent of people who, when viewing from a specified location and in a specified direction, will be expected to find it acceptable in terms of discomfort glare
wall pack security exterior light fixture designed to provide low energy, all night illumination of building exterior
wall washer asymmetric luminaire designed to provide wide and even illumination of interior or exterior walls. Can be recessed, suspended or track-mounted. Typical light source is double-ended halogen lamp (up to 500 Watts) or metal halide lamp (up to 150 Watts), or long compact fluorescent lamp (up to 2x80 Watts)
Wattage Wattage is the amount of electrical power consumed by a lamp or light fixture measured in “watts”. One watt is equal to the power dissipated by 1 ampere of electrical current flowing across a resistance of 1 ohm or the power produced by 1 ampere of electrical current under an electromotive force of 1 volt. One horsepower is equal to 746 watts. Formulae: watts =volts×amps,P=V×1,electrical power=electromotive force ×electric current.
wide flood halogen PAR or MR16 lamp with very wide beam, 42 – 50 degrees.    Used in ambient downlights, showcases (MR16) and other applications where wide area must be illuminated from a short distance
wire guard protective wire shield formed from heavy-gauge wires; designed to provide mechanical protection for fluorescent or metal halide luminaries in places where fixtures might be subject to mechanical damage -- i.e. gyms or warehouses.
work plane the plane / level above the floor, at which work usually is performed, and on which the light levels are specified and measured. Typically 30” for office spaces and 48” for showroom or retail environments
wrap-around fixture surface mounted fluorescent fixture with plastic (acrylic or polycarbonate) lens that completely covers, wraps the entire luminaire end-to-end

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