light acs
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An electric light is a device that produceslightby the flow ofelectric current. It is the most common form ofartificial lightingand is
essential to modern society, providing interior lighting for buildings and exterior light for evening and nighttime activities. Most
electric lighting is powered by centrally generated electric power, but lighting may also be powered by mobile or standby electric
generators or battery systems.Battery-powered lights, usually called "flashlights" or "torches", are used for portability and as backups
when the main lights fail. The two main families of electric light are incandescent lamps, which produce light by afilamentheated
white-hot by electric current, andgas-discharge lamps, which produce light by anelectric arcthrough a gas. The energy efficiency of
electric lighting has increased radically since the first demonstration ofarc lampsand the incandescentlight bulbof the 19th century.
Modern electric light sources come in a profusion of types and sizes adapted to a myriad of applications.
Types ofelectriclighting include:
incandescent light bulbs arc lamps gas discharge lamps, e.g.,fluorescent lightsandcompact fluorescent lamps,neon lamps,flood lamps, modernphotographic
flashes
lasers light-emitting diodes, includingOLEDs sulfur lampsDifferent types of lights have vastly differingefficienciesandcolor of light.[1]
NameOptical
spectrum
Nominalefficiency
(lm/W)
Lifetime
(MTTF)
(hours)
Color
temperature
(kelvin)
Color
Color
rendering
index
Incandescent light
bulbContinuous 4-17 2-20000 2400-3400 Warm white (yellowish) 100
Halogen lamp Continuous 16-23 3000-6000 3200 Warm white (yellowish) 100
Fluorescent lamp Mercuryline
+Phosphor52-100 (white)
8000-
200002700-5000*
White( various color
temperatures), as well as
saturated colors available
15-85
Metal halide lamp Quasi-
continuous 50-1156000-
20000 3000-4500 Cold white 65-93
Sulfur lamp Continuous 80-11015000-
200006000 Pale green 79
High pressure
sodiumBroadband 55-140
10000-
400001800-2200* Pinkish orange 0-70
Low pressure
sodiumNarrow line 100-200
18000-
200001800* Yellow, no color rendering 0
Light emitting
diode
Line plus
phosphor10-110 (white)
50,000-
100,000
Various whitefrom 2700 to
6000*
Various color temperatures,
as well as saturated colors
70-85
(white)
Induction Lamp
(External Coil)
Mercuryline
+Phosphor70-90 (white)
80,000-
100,000
Various white
from 2700 to
6000*
Various color temperatures,
as well as saturated colors
70-85
(white)
*Color temperature is defined as the temperature of ablack bodyemitting a similar spectrum; these spectra are quite different from
those of black bodies.
The most efficient source of electric light is the low-pressure sodium lamp. It produces, for all practical purposes,
amonochromaticorange/yellow light, which gives a similarly monochromatic perceprtion of any illuminated scene. For this reason, it
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mphttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Metal_halide_lamphttp://en.wikipedia.org/wiki/Metal_halide_lamphttp://en.wikipedia.org/wiki/Sulfur_lamphttp://en.wikipedia.org/wiki/Sulfur_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Light_emitting_diodehttp://en.wikipedia.org/wiki/Light_emitting_diodehttp://en.wikipedia.org/w/index.php?title=Induction_Lamp_(External_Coil)&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Induction_Lamp_(External_Coil)&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Induction_Lamp_(External_Coil)&action=edit&redlink=1http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Monochromatichttp://en.wikipedia.org/wiki/Monochromatichttp://en.wikipedia.org/wiki/Monochromatichttp://en.wikipedia.org/wiki/Monochromatichttp://en.wikipedia.org/wiki/Black_bodyhttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/w/index.php?title=Induction_Lamp_(External_Coil)&action=edit&redlink=1http://en.wikipedia.org/w/index.php?title=Induction_Lamp_(External_Coil)&action=edit&redlink=1http://en.wikipedia.org/wiki/Light_emitting_diodehttp://en.wikipedia.org/wiki/Light_emitting_diodehttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sulfur_lamphttp://en.wikipedia.org/wiki/Metal_halide_lamphttp://en.wikipedia.org/wiki/Phosphorhttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Halogen_lamphttp://en.wikipedia.org/wiki/Continuous_spectrumhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Colorhttp://en.wikipedia.org/wiki/Kelvinhttp://en.wikipedia.org/wiki/Color_temperaturehttp://en.wikipedia.org/wiki/Color_temperaturehttp://en.wikipedia.org/wiki/MTTFhttp://en.wikipedia.org/wiki/Watthttp://en.wikipedia.org/wiki/Lumen_(unit)http://en.wikipedia.org/wiki/Lighting_efficiencyhttp://en.wikipedia.org/wiki/Optical_spectrumhttp://en.wikipedia.org/wiki/Optical_spectrumhttp://www.parliament.the-stationery-office.co.uk/pa/cm200203/cmselect/cmsctech/747/747we81.htmhttp://en.wikipedia.org/wiki/Color_temperaturehttp://en.wikipedia.org/wiki/Luminous_efficiencyhttp://en.wikipedia.org/wiki/Sulfur_lamphttp://en.wikipedia.org/wiki/Organic_light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Laserhttp://en.wikipedia.org/wiki/Photographic_flashhttp://en.wikipedia.org/wiki/Photographic_flashhttp://en.wikipedia.org/wiki/Metal_halide_lamphttp://en.wikipedia.org/wiki/Neon_lamphttp://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Fluorescent_lighthttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Electricityhttp://en.wikipedia.org/wiki/Light_bulbhttp://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Gas-discharge_lamphttp://en.wikipedia.org/wiki/Electrical_filamenthttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Flashlighthttp://en.wikipedia.org/wiki/Battery_(electricity)http://en.wikipedia.org/wiki/Artificial_lightinghttp://en.wikipedia.org/wiki/Electric_currenthttp://en.wikipedia.org/wiki/Light 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is generally reserved for outdoor public lighting usages. Low-pressure sodium lights are favoured for public lighting by astronomers,
since thelight pollutionthat they generate can be easily filtered, contrary to broadband or continuous spectra.
Incandescent light bulb[edit source|editbeta]
Main article:Incandescent light bulb
The modern incandescent lightbulb, with a coiled filament of tungsten, was commercialized in the 1920s developed from the
carbonfilamentlamp introduced in about 1880. As well as bulbs for normal illumination, there is a very wide range, including low
voltage, low-power types often used as components in equipment, but now largely displaced by LEDs
There is currently interest in banning some types of filament lamp in some countries, such as Australia planning to ban standard
incandescent light bulbs by 2010, because they are inefficient at converting electricity to light. Sri Lanka has already banned
importing filament bulbs because of high use of electricity and less light. Less than 3% of the input energy is converted into usablelight. Nearly all of the input energy ends up as heat that, in warm climates, must then be removed from the building
byventilationorair conditioning, often resulting in more energy consumption. In colder climates where heating and lighting is
required during the cold and dark winter months, the heat byproduct has at least some value.
Halogen lamp[edit source|editbeta]
Main article:Halogen lamp
Halogen lamps are usually much smaller than standard incandescents, because for successful operation a bulb temperature over 200
C is generally necessary. For this reason, most have a bulb of fused silica (quartz), but sometimes aluminosilicate glass. This is often
sealed inside an additional layer of glass. The outer glass is a safety precaution, reducing UV emission and because halogen bulbs can
occasionally explode during operation. One reason is if the quartz bulb has oily residue fromfingerprints. The risk of burns or fire is
also greater with bare bulbs, leading to their prohibition in some places unless enclosed by the luminaire.
Those designed for 12 V or 24 V operation have compact filaments, useful for good optical control, also they have higher efficiencies
(lumens per watt) and better lives than non halogen types. The light output remains almost constant throughout life.Fluorescent lamp[edit source|editbeta]
Main article:Fluorescent lamp
Fluorescentlamps have much higher efficiency than filament lamps. For the same amount of light generated, they typically use around
one-quarter to one-third the power of an incandescent.
Fluorescents were mostly limited tolinearand a round 'Circline' lamp until the 1980s, with other shapes never gaining much
popularity. Thecompact fluorescent lamp(CFL) was commercialized in the early 1980s.
Most CFLs have a built-inelectrical ballastand fit into a standard screw or bayonet base. Some make use of a separate ballast so that
the ballast and tube can be replaced separately.
Typical average lifetime ratings for linear fluorescent tubes are 10,000 and 20,000 hours, compared to 750 hours (110 V) and 1000
hours (240 V) for filament lamps.
Some types of fluorescent lamp ballast have difficulty starting lamps in very cold conditions, so lights used outdoors in cold climates
need to be designed for outdoor use to work reliably.
Fluorescents come in a range of different color temperatures. In some countries cool white (CW) is most popular, while in some,
warmer whites predominate.
In the United States, fluorescents most often come in cool white (CW), with some home bulbs being a warm white (WW), which has
apinkishcolor. In between there is an "enhanced white" (EW), which is more neutral. There is also a very cold daylight white (DW).
Compact fluorescent lamps are usually considered warm white, though many have a yellowish cast like an incandescent. "Warm" and
"cool" are entirely relative terms and almostarbitrarysocolor temperatureand thecolor rendering index(CRI) are used as absolute
scales of color for fluorescents, and sometimes for other types of lighting.
LED lamp[edit source|editbeta]
Main article:Solid-state lighting
Solid stateLEDshave been popular as indicator lights since the 1970s. In recent years,efficacyand output have risen to the point
where LEDs are now being used in niche lighting applications.
IndicatorLEDsare known for their extremely long life, up to 100,000 hours, but lighting LEDs are operated much less conservatively
(due to high LED cost per watt), and consequently have much shorter lives.
Due to the relatively high cost per watt, LED lighting is most useful at very low powers, typically for lamp assemblies of under 10 W.
LEDs are currently most useful andcost-effectivein low power applications, such asnightlightsandflashlights. Colored LEDs can
also be used for accent lighting, such as for glass objects, and even in fake ice cubes for drinks at parties. They are also being
increasingly used as holiday lighting.
LEDefficiencies vary over a very wide range. Some have lower efficiency than filament lamps, and some significantly higher. LED
performance in this respect is prone to being misinterpreted, as the inherent directionality of LEDs gives them a much higher light
intensity in one direction per given total light output.
Single colorLEDsare well developed technology, but white LEDs at time of writing still have some unresolved issues.
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ht-emitting_diodeshttp://en.wikipedia.org/wiki/Light-emitting_diodeshttp://en.wikipedia.org/wiki/Light-emitting_diodeshttp://en.wikipedia.org/wiki/Light-emitting_diodeshttp://en.wikipedia.org/wiki/Light-emitting_diodeshttp://en.wikipedia.org/wiki/Flashlighthttp://en.wikipedia.org/wiki/Nightlighthttp://en.wikipedia.org/wiki/Cost-effectivehttp://en.wikipedia.org/wiki/Light-emitting_diodeshttp://en.wikipedia.org/wiki/Luminous_efficacyhttp://en.wikipedia.org/wiki/Light-emitting_diodeshttp://en.wikipedia.org/wiki/Solid-state_lightinghttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=5http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=5http://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Color_temperaturehttp://en.wikipedia.org/wiki/Arbitraryhttp://en.wikipedia.org/wiki/Pinkhttp://en.wikipedia.org/wiki/Ballast_(electrical)http://en.wikipedia.org/wiki/Compact_fluorescent_lamphttp://en.wikipedia.org/wiki/Linearhttp://en.wikipedia.org/wiki/Fluorescent_lightinghttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=4http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=4http://en.wikipedia.org/wiki/Fingerprinthttp://en.wikipedia.org/wiki/Halogen_lamphttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=3http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=3http://en.wikipedia.org/wiki/Air_conditioninghttp://en.wikipedia.org/wiki/Ventilation_(architecture)http://en.wikipedia.org/wiki/Electrical_filamenthttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=2http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=2http://en.wikipedia.org/wiki/Light_pollution 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1. CRI is not particularly good, resulting in less than accurate color rendition.2. The light distribution from the phosphor does not fully match the distribution of light from the LED die, so color temperature
varies at differing angles.
3. Phosphor performance degrades over time, resulting in change of color temperature and falling output. With some LEDsdegradation can be quite fast.
4. Limited heat tolerance means that the amount of power packable into a lamp assembly is a fraction of the power usable in asimilarly sized incandescent lamp.
LED technology is useful for lighting designers because of its low power consumption, low heat generation, instantaneous on/off
control, and in the case of single color LEDs, continuity of color throughout the life of the diode and relatively low cost of
manufacture.In the last few years, software has been developed to merge lighting and video by enabling lighting designers to stream video content
to their LED fixtures, creating low resolution video walls.
For general domestic lighting, total cost of ownership of LED lighting is still much higher than for other well established lighting
types.
Carbon arc lamp[edit source|editbeta]
Main article:Arc lamp
Carbon arc lamps consist of two carbon rodelectrodesin open air, supplied by a current-limitingballast. Theelectric arcis struck by
touching the rods then separating them. The ensuing arc heats the carbon tips to white heat. These lamps have higher efficiency than
filament lamps, but the carbon rods are short lived and require constant adjustment in use. The lamps produce significant ultra-
violetoutput, they require ventilation when used indoors, and due to their intensity they need protecting from direct sight.
Carbon arc lamps operate at high powers, and had high efficiency compared to other pre-1920s light sources. They also are a point
source of light. These properties made them ideally suited to search lights, follow spots and film projector lights.
Their need for ongoing attendance and adjustment, and frequent rod replacement made them ill suited to general lighting, though they
were used for high power lighting in the years when nothing else with comparable output power existed. Carbon arcs fell out of use
even for niche applications during and after World War 2.
Discharge lamp[edit source|editbeta]
A discharge lamp has a glass or silica envelope containing two metalelectrodesseparated by a gas. Gases used
include,neon,argon,xenon,sodium,metal halide, andmercury.
The core operating principle is much the same as the carbon arc lamp, but the term 'arc lamp' is normally used to refer to carbon arc
lamps, with more modern types of gas discharge lamp normally called 'discha
With some discharge lamps, very high voltage is used to strike the arc. This requires an electrical circuit called an igniter, which is
part of theballastcircuitry. After the arc is struck, the internal resistance of the lamp drops to a low level, and the ballast limits the
current to the operating current. Without a ballast, excess current would flow, causing rapid destruction of the lamp.
Some lamp types contain a little neon, which permits striking at normal running voltage, with no external igniter circuitry. Low
pressure sodium lampsoperate this way.
The simplest ballasts are just an inductor, and are chosen where cost is the deciding factor, such as street lighting. More advanced
electronic ballasts may be designed to maintain constant light output over the life of the lamp, may drive the lamp with a square wave
to maintain completely flicker-free output, and shut down in the event of certain faults.
Lamp life expectancy[edit source|editbeta]
This section does notciteanyreferences or sources. Please help improve this section byadding citations
to reliable sources. Unsourced material may be challenged andremoved.(August 2012)
Life expectancy is defined as the number of hours of operation for a lamp until 50% of them fail. This means that it is possible for
some lamps to fail after a short amount of time and for some to last significantly longer than the rated lamp life. This is an average
(median) life expectancy. Production tolerances as low as 1% can create a variance of 25% in lamp life. For LEDs, lamp life is when50% of lamps have lumen output drop to 70% or less.
Lamps are also sensitive to switching cycles. The rapid heating of a lamp filament [dubiousdiscuss] or electrodes when a lamp is turned on
is the most stressful event on the lamp. Most test cycles have the lamps on for 3 hours and then off for 20 minutes. (Some standard had
to be used since it is unknown how the lamp will be used by consumers.) This switching cycle repeats until the lamps fail and the data
is recorded. If switching is increased to only 1 hour on, the lamp life is usually reduced because the number of times the lamp has been
turned on has increased. Rooms with frequent switching (bathroom, bedrooms, etc.) can expect much shorter lamp life than what is
printed on the box.
Vendors[edit source|editbeta]
GELighting
http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=6http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=6http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=6http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=6http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=6http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=6http://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Electrical_ballasthttp://en.wikipedia.org/wiki/Electrical_ballasthttp://en.wikipedia.org/wiki/Electrical_ballasthttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Ultra-violethttp://en.wikipedia.org/wiki/Ultra-violethttp://en.wikipedia.org/wiki/Ultra-violethttp://en.wikipedia.org/wiki/Ultra-violethttp://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=7http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=7http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=7http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=7http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=7http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=7http://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Metal_halidehttp://en.wikipedia.org/wiki/Metal_halidehttp://en.wikipedia.org/wiki/Metal_halidehttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Ballast_(electrical)http://en.wikipedia.org/wiki/Ballast_(electrical)http://en.wikipedia.org/wiki/Ballast_(electrical)http://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=8http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=8http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=8http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=8http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=8http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=8http://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/Wikipedia:Disputed_statementhttp://en.wikipedia.org/wiki/Wikipedia:Disputed_statementhttp://en.wikipedia.org/wiki/Wikipedia:Disputed_statementhttp://en.wikipedia.org/wiki/Talk:Electric_light#Dubioushttp://en.wikipedia.org/wiki/Talk:Electric_light#Dubioushttp://en.wikipedia.org/wiki/Talk:Electric_light#Dubioushttp://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=9http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=9http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=9http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=9http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=9http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=9http://en.wikipedia.org/wiki/GEhttp://www.gelighting.com/http://www.gelighting.com/http://www.gelighting.com/http://en.wikipedia.org/wiki/File:Question_book-new.svghttp://www.gelighting.com/http://en.wikipedia.org/wiki/GEhttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=9http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=9http://en.wikipedia.org/wiki/Talk:Electric_light#Dubioushttp://en.wikipedia.org/wiki/Wikipedia:Disputed_statementhttp://en.wikipedia.org/wiki/Wikipedia:Verifiability#Burden_of_evidencehttp://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Help:Introduction_to_referencing/1http://en.wikipedia.org/wiki/Wikipedia:Verifiabilityhttp://en.wikipedia.org/wiki/Wikipedia:Citing_sourceshttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=8http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=8http://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Sodium_vapor_lamphttp://en.wikipedia.org/wiki/Ballast_(electrical)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Metal_halidehttp://en.wikipedia.org/wiki/Sodiumhttp://en.wikipedia.org/wiki/Xenonhttp://en.wikipedia.org/wiki/Argonhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=7http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=7http://en.wikipedia.org/wiki/Ultra-violethttp://en.wikipedia.org/wiki/Ultra-violethttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electrical_ballasthttp://en.wikipedia.org/wiki/Electrodehttp://en.wikipedia.org/wiki/Arc_lamphttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=6http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=6 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Osram PhilipsLighting HalonixPublic lighting[edit source|editbeta]
The total amount of artificial light (especially fromstreet light) is sufficient for cities to be easily visible at night from the air, and
from space. This light is the source oflight pollutionthat burdensastronomersand others.
Human-made lights highlight particularly developed or populated areas of the Earth's surface, including the seaboards of Europe, the
eastern United States, Japan and South Korea.
See also
http://en.wikipedia.org/wiki/Osramhttp://en.wikipedia.org/wiki/Osramhttp://en.wikipedia.org/wiki/Philipshttp://www.lighting.philips.com/gl_en/index.php?main=global&parent=global&id=global&lang=enhttp://www.lighting.philips.com/gl_en/index.php?main=global&parent=global&id=global&lang=enhttp://www.lighting.philips.com/gl_en/index.php?main=global&parent=global&id=global&lang=enhttp://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=10http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=10http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=10http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=10http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=10http://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=10http://en.wikipedia.org/wiki/Street_lighthttp://en.wikipedia.org/wiki/Street_lighthttp://en.wikipedia.org/wiki/Street_lighthttp://en.wikipedia.org/wiki/Light_pollutionhttp://en.wikipedia.org/wiki/Light_pollutionhttp://en.wikipedia.org/wiki/Light_pollutionhttp://en.wikipedia.org/wiki/Astronomyhttp://en.wikipedia.org/wiki/Astronomyhttp://en.wikipedia.org/wiki/Astronomyhttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/File:Earthlights_dmsp.jpghttp://en.wikipedia.org/wiki/Astronomyhttp://en.wikipedia.org/wiki/Light_pollutionhttp://en.wikipedia.org/wiki/Street_lighthttp://en.wikipedia.org/w/index.php?title=Electric_light&veaction=edit§ion=10http://en.wikipedia.org/w/index.php?title=Electric_light&action=edit§ion=10http://www.lighting.philips.com/gl_en/index.php?main=global&parent=global&id=global&lang=enhttp://en.wikipedia.org/wiki/Philipshttp://en.wikipedia.org/wiki/Osram -
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Solid-state lightingA compact fluorescent lamp (CFL), also called compact fluorescent light, energy-saving light, and compact fluorescent tube, is
afluorescent lampdesigned to replace anincandescent lamp; some types fit intolight fixturesformerly used for incandescent lamps.
The lamps use a tube which is curved or folded to fit into the space of an incandescent bulb, and a compactelectronic ballastin the
base of the lamp.
A neon lamp (also neon glow lamp) is a miniaturegas discharge lampthat typically containsneongas at a lowpressurein a glass
capsule. Only a thin region adjacent to the electrodes glows in these lamps, which distinguishes them from the much longer and
brighterneon tubesused for signage. The term "neon lamp" is generally extended to lamps with similar design that operate with
different gases. Neon glow lamps were very common in the displays of electronic instruments through the 1970s; the basic design of
neon lamps is now incorporated in contemporaryplasma displays.
A metal-halide lamp is an electric light that produces light by anelectric arcthrough a gaseous mixture of
vaporizedmercuryandmetal halides[1][2](compounds of metals withbromineoriodine). It is a type ofhigh-intensity
discharge(HID)gas discharge lamp.[1]Developed in the 1960s, they are similar tomercury vapor lamps,[1]but contain additional metal
halide compounds in the arc tube, which improve the efficacy andcolor renditionof the light. (SSL) refers to a type oflightingthat
usessemiconductor light-emitting diodes(LEDs),organic light-emitting diodes(OLED), orpolymer light-emitting diodes(PLED) as
sources of illumination rather thanelectrical filaments,plasma(used inarc lampssuch asfluorescent lamps), orgas.
A light-emitting diode (LED) is asemiconductorlight source.[7]LEDs are used as indicator lamps in many devices and are
increasingly used forgeneral lighting. Appearing as practical electronic components in 1962,[8]early LEDs emitted low-intensity red
light, but modern versions are available across thevisible,ultraviolet, andinfraredwavelengths, with very high brightness.
Quantity of Illumination
Light Output
The most common measure of light output (or luminous flux) is the lumen. Light sources are labeled with an output rating in lumens.
For example, a T12 40-watt fluorescent lamp may have a rating of 3050 lumens. Similarly, a light fixture's output can be expressed in
lumens. As lamps and fixtures age and become dirty, their lumen output decreases (i.e., lumen depreciation occurs). Most lamp ratings
are based on initial lumens (i.e., when the lamp is new).
Light Level
http://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Fluorescent_lamphttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Light_fixturehttp://en.wikipedia.org/wiki/Light_fixturehttp://en.wikipedia.org/wiki/Light_fixturehttp://en.wikipedia.org/wiki/Electronic_ballasthttp://en.wikipedia.org/wiki/Electronic_ballasthttp://en.wikipedia.org/wiki/Electronic_ballasthttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Neon_signhttp://en.wikipedia.org/wiki/Neon_signhttp://en.wikipedia.org/wiki/Neon_signhttp://en.wikipedia.org/wiki/Plasma_displayhttp://en.wikipedia.org/wiki/Plasma_displayhttp://en.wikipedia.org/wiki/Plasma_displayhttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Metal_halideshttp://en.wikipedia.org/wiki/Metal_halideshttp://en.wikipedia.org/wiki/Metal_halideshttp://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Grondzik-2http://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Grondzik-2http://en.wikipedia.org/wiki/Brominehttp://en.wikipedia.org/wiki/Brominehttp://en.wikipedia.org/wiki/Brominehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/High-intensity_dischargehttp://en.wikipedia.org/wiki/High-intensity_dischargehttp://en.wikipedia.org/wiki/High-intensity_dischargehttp://en.wikipedia.org/wiki/High-intensity_dischargehttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Mercury_vapor_lamphttp://en.wikipedia.org/wiki/Mercury_vapor_lamphttp://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Organic_light-emitting_diodehttp://en.wikipedia.org/wiki/Organic_light-emitting_diodehttp://en.wikipedia.org/wiki/Organic_light-emitting_diodehttp://en.wikipedia.org/wiki/Polymer_light-emitting_diodehttp://en.wikipedia.org/wiki/Polymer_light-emitting_diodehttp://en.wikipedia.org/wiki/Polymer_light-emitting_diodehttp://en.wikipedia.org/wiki/Electrical_filamenthttp://en.wikipedia.org/wiki/Electrical_filamenthttp://en.wikipedia.org/wiki/Electrical_filamenthttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Arc_lampshttp://en.wikipedia.org/wiki/Arc_lampshttp://en.wikipedia.org/wiki/Arc_lampshttp://en.wikipedia.org/wiki/Fluorescent_lampshttp://en.wikipedia.org/wiki/Fluorescent_lampshttp://en.wikipedia.org/wiki/Fluorescent_lampshttp://en.wikipedia.org/wiki/Gas_lightinghttp://en.wikipedia.org/wiki/Gas_lightinghttp://en.wikipedia.org/wiki/Gas_lightinghttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-7http://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-7http://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-7http://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-LemelsonMIT-8http://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-LemelsonMIT-8http://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-LemelsonMIT-8http://en.wikipedia.org/wiki/Visible_spectrumhttp://en.wikipedia.org/wiki/Visible_spectrumhttp://en.wikipedia.org/wiki/Visible_spectrumhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Infraredhttp://en.wikipedia.org/wiki/Ultraviolethttp://en.wikipedia.org/wiki/Visible_spectrumhttp://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-LemelsonMIT-8http://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Light-emitting_diode#cite_note-7http://en.wikipedia.org/wiki/Semiconductorhttp://en.wikipedia.org/wiki/Gas_lightinghttp://en.wikipedia.org/wiki/Fluorescent_lampshttp://en.wikipedia.org/wiki/Arc_lampshttp://en.wikipedia.org/wiki/Plasma_(physics)http://en.wikipedia.org/wiki/Electrical_filamenthttp://en.wikipedia.org/wiki/Polymer_light-emitting_diodehttp://en.wikipedia.org/wiki/Organic_light-emitting_diodehttp://en.wikipedia.org/wiki/Light-emitting_diodehttp://en.wikipedia.org/wiki/Lightinghttp://en.wikipedia.org/wiki/Color_rendering_indexhttp://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Mercury_vapor_lamphttp://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Hordeski-1http://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/High-intensity_dischargehttp://en.wikipedia.org/wiki/High-intensity_dischargehttp://en.wikipedia.org/wiki/Iodinehttp://en.wikipedia.org/wiki/Brominehttp://en.wikipedia.org/wiki/Metal_halide_lamp#cite_note-Grondzik-2http://en.wikipedia.org/wiki/Metal_halideshttp://en.wikipedia.org/wiki/Metal_halideshttp://en.wikipedia.org/wiki/Mercury_(element)http://en.wikipedia.org/wiki/Electric_archttp://en.wikipedia.org/wiki/Plasma_displayhttp://en.wikipedia.org/wiki/Neon_signhttp://en.wikipedia.org/wiki/Pressurehttp://en.wikipedia.org/wiki/Neonhttp://en.wikipedia.org/wiki/Gas_discharge_lamphttp://en.wikipedia.org/wiki/Electronic_ballasthttp://en.wikipedia.org/wiki/Light_fixturehttp://en.wikipedia.org/wiki/Incandescent_light_bulbhttp://en.wikipedia.org/wiki/Fluorescent_lamp 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Light intensity measured on a plane at a specific location is called illuminance. Illuminance is measured in footcandles, which are
workplane lumens per square foot. You can measure illuminance using a light meter located on the work surface where tasks are
performed. Using simple arithmetic and manufacturers' photometric data, you can predict illuminance for a defined space. (Lux is the
metric unit for illuminance, measured in lumens per square meter. To convert footcandles to lux, multiply footcandles by 10.76.)
Brightness
Another measurement of light isluminance, sometimes called brightness. This measures light "leaving" a surface in a particular
direction, and considers the illuminance on the surface and the reflectance of the surface.
The human eye does not see illuminance; it sees luminance. Therefore, the amount of light delivered into the space and the reflectance
of the surfaces in the space affects your ability to see.
Refer to theGLOSSARYat the end of this document for more detailed definitions.
Quantity Measures
Luminous flux is commonly called light output and is measured in lumens (lm). Illuminance is called light level and is measured in footcandles (fc). Luminance is referred to as brightness and is measured in footlamberts (fL) or candelas/m2 (cd/m2).
Determining Target Light Levels
The Illuminating Engineering Society of North America has developed a procedure for determining the appropriate average light level
for a particular space. This procedure ( used extensively by designers and engineers ( recommends a target light level by considering
the following:
the task(s) being performed (contrast, size, etc.) the ages of the occupants the importance of speed and accuracy
Then, the appropriate type and quantity of lamps and light fixtures may be selected based on the following:
fixture efficiency lamp lumen output the reflectance of surrounding surfaces the effects of light losses from lamp lumen depreciation and dirt accumulation room size and shape availability of natural light (daylight)
When designing a new or upgraded lighting system, one must be careful to avoid overlighting a space. In the past, spaces were
designed for as much as 200 footcandles in places where 50 footcandles may not only be adequate, but superior. This was partly due
to the misconception that the more light in a space, the higher the quality. Not only does overlighting waste energy, but it can also
reduce lighting quality. Refer to Exhibit 2 for light levels recommended by the Illuminating Engineering Society of North America.
Within a listed range of illuminance, three factors dictate the proper level: age of the occupant(s), speed and accuracy requirements,
and background contrast.
For example, to light a space that uses computers, the overhead light fixtures should provide up to 30 fc of ambient lighting. The task
lights should provide the additional footcandles needed to achieve a total illuminance of up to 50 fc for reading and writing. For
illuminance recommendations for specific visual tasks, refer to the IES Lighting Handbook, 1993, or to the IES Recommended
Practice No. 24 (for VDT lighting).
Quality Measures
Visual comfort probability (VCP) indicates the percent of people who are comfortable with the glare from a fixture. Spacing criteria (SC) refers to the maximum recommended distance between fixtures to ensure uniformity. Color rendering index (CRI) indicates the color appearance of an object under a source as compared to a reference source.
http://www-is.informatik.uni-oldenburg.de/~dibo/teaching/mm/pages/light-fundamentals.html#glosshttp://www-is.informatik.uni-oldenburg.de/~dibo/teaching/mm/pages/light-fundamentals.html#glosshttp://www-is.informatik.uni-oldenburg.de/~dibo/teaching/mm/pages/light-fundamentals.html#glosshttp://www-is.informatik.uni-oldenburg.de/~dibo/teaching/mm/pages/light-fundamentals.html#gloss -
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Quality of IlluminationImprovements in lighting quality can yield high dividends for US businesses. Gains in worker productivity may result by providing
corrected light levels with reduced glare. Although the cost of energy for lighting is substantial, it is small compared with the cost of
labor. Therefore, these gains in productivity may be even more valuable than the energy savings associated with new lighting
technologies. In retail spaces, attractive and comfortable lighting designs can attract clientele and enhance sales.
Three quality issues are addressed in this section.
glare uniformity of illuminance color rendition
Glare
Perhaps the most important factor with respect to lighting quality is glare. Glare is a sensation caused by luminances in the visual field
that are too bright. Discomfort, annoyance, or reduced productivity can result.
A bright object alone does not necessarily cause glare, but a bright object in front of a dark background, however, usually will cause
glare. Contrastis the relationship between the luminance of an object and its background. Although the visual task generally becomes
easier with increased contrast, too much contrast causes glare and makes the visual task much more difficult.
You can reduce glare or luminance ratios by not exceeding suggested light levels and by using lighting equipment designed to reduce
glare. A louver or lens is commonly used to block direct viewing of a light source. Indirect lighting, or uplighting, can create a low
glare environment by uniformly lighting the ceiling. Also, proper fixture placement can reduce reflected glare on work surfaces or
computer screens. Standard data now provided with luminaire specifications include tables of its visual comfort probability (VCP)
ratings for various room geometries. The VCP index provides an indication of the percentage of people in a given space that would
find the glare from a fixture to be acceptable. A minimum VCP of 70 is recommended for commercial interiors, while luminaires with
VCPs exceeding 80 are recommended in computer areas.
Uniformity of Illuminance on TasksThe uniformity of illuminance is a quality issue that addresses how evenly light spreads over a task area. Although a room's average
illuminance may be appropriate, two factors may compromise uniformity.
improper fixture placement based on the luminaire's spacing criteri a(ratio of maxim recommended fixture spacing distanceto mounting height above task height)
fixtures that are retrofit with reflectors that narrow the light distributionNon-uniform illuminance causes several problems:
inadequate light levels in some areas visual discomfort when tasks require frequent shifting of view from underlit to overlit areas bright spots and patches of light on floors and walls that cause distraction and generate a low quality appearance
Color Rendition
The ability to see colors properly is another aspect of lighting quality. Light sources vary in their ability to accurately reflect the true
colors of people and objects. The color rendering index (CRI) scale is used to compare the effect of a light source on the color
appearance of its surroundings.
A scale of 0 to 100 defines the CRI. A higher CRI means better color rendering, or less color shift. CRIs in the range of 75-100 are
considered excellent, while 65-75 are good. The range of 55-65 is fair, and 0-55 is poor. Under higher CRI sources, surface colors
appear brighter, improving the aesthetics of the space. Sometimes, higher CRI sources create the illusion of higher illuminance levels.
The CRI values for selected light sources are tabulated with other lamp data in Exhibit 3.
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7/29/2019 light acs
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12v LED Dimmer
3Ch DMX Decoder
DMX Controller
20A Power Supply
Wall Plug Adapter
12v Wiring
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