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Accent Lighting
Concentrated light on a subject which highlights
it and causes it to stand out from its surrounding.
Depending on degree of drama desired, accent
light should minimally be 10x the general light
or ambient light. |
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Accommodation
The involuntary muscular process by which the eye
changes focus from one distance to another. |
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Adaptation
The involuntary process by which the visual system
changes its sensitivity, depending on the luminances
prevailing in the visual field. The process involves both
the iris and the light sensitive cells of the retina. |
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ALTO® Lamps
ALTO means that the lamps pass the US government's
TCLP test (Toxicity Characteristic Leaching Procedure).
ALTO linear fluorescent lamps have the lowest mercury
content of any linear fluorescent lamps in the market. |
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Ballast
The ballast is an electrical device that performs two
basic functions: 1) provides the starting voltage and
2) limits the current to sustain lamp operation.
Ballast types for fluorescent lamps:
Instant Start: Instant start electronic ballasts are the
most popular type of electronic ballast today because
they provide maximum energy savings and they start
lamps without delay or flashing. Since they do not
provide lamp electrode heating, instant start ballasts
consume less energy than comparable rapid start,
program rapid start or programmed start ballasts.
As a result, they provide the most energy efficient
solution to fluorescent lamp ballasting. The instant
start ballast uses 1.5 to 2 watts less energy per lamp
than the rapid start alternative.
Instant-start electronic ballasts provide a high initial
voltage (typically 600V for F32T8 lamps)to start the
lamp. This high voltage is required to initiate discharge
between the unheated electrodes of the lamp.
However, the cold electrodes of lamps operated by an instant start ballast may deteriorate more quickly
than the warmed electrodes of lamps operated by
a rapid start, program rapid start or programmed
start ballast. Lamps operated by instant start ballasts
will typically withstand 10-15K switch cycles. Instant start ballasts are typically wired in parallel. This means
that if one lamp fails,the other lamps in the circuit
will remain lit.
Rapid Start: Rapid start ballasts have a separate set
of windings which provide a low voltage (approx. 3.5
volts) to the electrodes for one second prior to lamp
ignition. A starting voltage somewhat lower than that
of instant ballast (typically 450-550V for F32T8 lamps)
is applied, striking an electrical arc inside the lamp.
Most rapid start electronic ballasts continue to heat
the electrode even after the lamp has started, which results in a power loss of 1.5 to 2 watts per lamp.
Lamps operated by a rapid start electronic ballast
will typically withstand 15-20K switch cycles. Rapid
start ballasts are typically wired in series. This means
that if one lamp fails, all other lamps in the circuit will extinguish.
Programmed Start: Programmed start (PS) electronic
ballasts provide maximum lamp life in frequent starting
conditions (up to 50,000 starts). PS ballasts use a
custom integrated circuit (IC) which monitors lamp
and ballast conditions to ensure optimal system lighting
performance. Life Program rapid start ballasts, PS
ballasts also precisely heat the lamp cathodes. However,
PS ballasts heat the lamp cathodes to 700°C prior to lamp ignition. This puts the least amount of stress
on the lamp electrodes, resulting in maximum lamp life
regardless of the number of lamp starts. Programmed
start ballasts are typically wired in series.
Ballast types for HID lamps:
Reactor: Single coil, very efficient, but poor voltage
regulation to the lamp.
Constant Wattage Autotransformer (CWA):
Employing two coils, the ballast is less efficient then
reactor types, but have better voltage regulation.
Most popular type in use.
Magnetically Regulated (Mag Reg) or Regulated
Lag (Reg Lag): Three coils make for very effective
voltage regulation but also not very efficient.
Electronic: Allows for both high efficiency
and the best voltage regulation. |
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Beam Angle
The beam angle defines the light pattern around the
beam's central axis for which the luminous intensity
is half that of the maximum luminous intensity. |
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Candela (Luminous Intensity)/Candlepower (USA)
The intensity base unit for light. Intensity is the luminous
flux emitted from a point per unit solid angle into a
particular direction, regardless of distance. |
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Color Rendering Index (CRI)
A method for describing the effect of a light source
on the color appearance of objects, compared to
a reference source of the same color temperature
(CCT). The highest CRI attainable is 100. Originally
based on an eight standardized color comparisons, it was later extended to fourteen colors. |
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Color Temperature or Correlated
Color Temperature (CCT)
The color temperature of a light emitter refers to the
temperature to which one would have to heat a
"blackbody" source (Planckian radiator) to produce
light of similar overall appearance or chromaticity. A
low color temperature implies warmer color (more
yellow/red) light while high color temperature implies
a cooler light (more blue). The standard unit for color
temperature measurement is expressed in Kelvin (K). |
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Efficacy
The expression of efficiency in converting power
(watts)into light (lumens). Expressed as lumens
per watt or l/w. |
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Exitance
Refers to the total amount of visible light leaving
a surface in all directions. Unit for luminous
exitance is lumens per square meter (lm/m2) |
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Field Angle
The field angle defnes the light pattern around the
beam's central axis for which the luminous intensity is
10% that of the maximum luminous intensity. |
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Flux
Is the basic measure of light flow. Flux, expressed
in lumens, includes only visible light and is weighted to
match the response of the human eye. Thus it is a
measure of Photometry rather than Radiometry. |
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Footcandle
The unit of measure for the density of light on a
surface unique to the USA.One footcandle is equal
to one lumen per foot (lm/ft2). One footcandle = 10.674 lux. |
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Glare
Glare is an interference with visual perception
caused by an uncomfortably bright light source or
reflection within one's field of view; a form of visual
noise. In its simplest form, glare (unwanted light) is a
consequence of the human eye to adapt to different light levels. In the case of glare, the eye adapts
to the high level of the glare source, which makes it
difficult to perceive details in the now too dark
work area.
Direct Glare: Glare resulting from high luminances
in the visual environment that are directly visible
from a viewers position; such as an insufficiently
shielded luminaire.
Reflected Glare or Veiling Reflection: A reflection
of incident light that partially or totally obscures
the details to be seen on a surface by reducing
the contrast.
Discomfort Glare: Glare which is distracting or
uncomfortable (subjective), which interferes with the
perception of visual information, but which does not
significantly reduce visual performance.
Disability Glare: The effect of light which significantly
reduces visual performance and perception; such as
car high beams in your face on a dark country road. |
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General Lighting (Ambient Lighting)
Lighting designed to deliver a predominately
uniform level of light throughout an area. |
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Illuminance
The total density of visible light—from all directions—illuminating, falling on or incident to, a surface. Standard unit of measure for illuminance is LUX (lx) which is lumens per square meter (lm/m2).
See Footcandle. |
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Inverse Square Law
This law says that the measured flux density from
a light source decreases along any line from the
source. It falls off in proportion to the square of
the relative distance traversed. Thus the illuminance
measurement 2 feet from the light source will be
1/4 of the measurement 1 foot from the source—not 1/2. |
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Initial vs. Mean Lumens
The measured luminous output of a new light source
versus the output at 40% of lamp life. |
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Kelvin
The Kelvin unit is the basis of all temperature
measurement. In lighting, Kelvin is the unit of
measure for Color Temperature used to indicate
the overall color of the light produced from
a source. See Color Temperature. |
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Kilowatt Hour (kWh)
The measure of electrical energy from which
electricity billing is determined. For example,
at the rate of $0.10 per kWh, a 100 watt lamp
operating for 2000 hours will cost $20.00
(100 x 2000/1000 = 200 kWh x .10 = $20.00) |
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Light
Radiant energy that stimulates the sense of sight.
The "visible" part of the ectromagnetic spectrum
from 380 - 770 nm. Light is the energy which allows us
to see. |
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Luminaire (light fixture)
A complete lighting unit which consists of lamp(s),
ballast(s)—if applicable—as well as mechanism for
light distribution, lamp protection and alignment and
connection to power. |
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Luminaire Efficacy
The ratio of luminous flux emitted by the fixture
to that emitted by the lamp(s) within the fixture.
Expressed as a percentage. |
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Luminance (The physical measure of brightness)
Luminance is the amount of visible light leaving a point
on a surface in a given direction. The light leaving the
surface can be due to re flection, transmission and/or emission. Standard unit of luminance is candela per
square meter (cd/m2). |
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Photometry
Photometry is the science of measuring visible light in
units that are weighted according to the sensitivity of the human eye known as the Visual Wavelength (Vλ) factor. Photometric theory does not address how we
perceive colors. |
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Radiometry
Radiometry is the science of quantifying the phenomena
of electromagnetic radiation. In our context, we are
interested in light, the limited range of electromagnetic
radiation that is visible to the human eye, sometimes
extended to the areas of infrared and ultraviolet. |
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Rated Average Life
The length of operation (in hours) at which point
an average of 50% of a large sample of lamps will still
be operational and 50% will not. |
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Task Lighting
Lighting designed for a specific visible operation which
requires higher light levels; most often characterized by
proximity to that task. |
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Voltage
A measure of electromotive force or simply said, the
pressure of electricity. This is analogous to pressure in a
water line. In this catalog,voltage refers to supply voltage required by the lamp (incandescent) or operating
voltage required by the arc tube (discharge lamps). |
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Watt
Unit used to measure electric power consumed by
a lamp or any electrical device. |
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