Application

The use to which a lighting system will be put; for example,
a lamp may be intended for indoor residential applications.

Average Rated Life

The number of hours at which half of a large group of
product samples fail under standard test conditions. Rated life is a median
value; any lamp or group of lamps may vary from the published rated life.

LED Beam Angle

The angle at which luminous intensity is 50 percent of the
maximum intensity.

Color Rendering Index (CRI)

A rating index commonly used to represent how well a light
source renders the colors of objects that it illuminates. For a CRI value of
100, the maximum value, the colors of objects can be expected to be seen as
they would appear under an incandescent or daylight spectrum of the same
correlated color temperature (CCT). Sources with CRI values less than 50 are
generally regarded as rendering colors poorly, that is, colors may appear
unnatural.

Compact Fluorescent Lamp (CFL)

A family of single-ended fluorescent-discharge light sources.

Correlated Color Temperature (CCT)

A specification for white light sources used to describe the
dominant color tone along the dimension from warm (yellows and reds) to cool
(blue). Lamps with a CCT rating below 3200 K are usually considered warm
sources, whereas those with a CCT above 4000 K usually considered cool in
appearance. Temperatures in between are considered neutral in appearance.
Technically, CCT extends the practice of using temperature, in kelvins (K), for
specifying the spectrum of light sources other than blackbody radiators.

Current (C)

An electric current is a flow of electric charge. In
electric circuits this charge is often carried by moving electrons in a wire.
It can also be carried by ions in an electrolyte, or by both ions and electrons
such as in a plasma.

Driver

For light emitting diodes, a device that regulates the
voltage and current powering the source.

LED Efficacy

The ratio of light output (in lumens) to LED power (in
watts).

Fixture

A complete lighting unit consisting of lamp or lamps and the
parts designed to distribute the light, position and protect the lamp(s), and
connect the lamp(s) to the power supply. (Also referred to as luminaire.)

Frequency (Hz)

The number of cycles completed by a periodic wave in a given
unit of time. Frequency is commonly reported in cycles per second, or hertz
(Hz).

Kelvin Color Temperature

A measure of the color of a light source relative to a black
body at a particular temperature expressed in degrees Kelvin (K). Incandescent
lights have a low color temperature (approximately 2800K) and have a
red-yellowish tone; daylight has a high color temperature (approximately 6000K)
and appears bluish (the most popular fluorescent light, Cool White, is rated at
4100K). Today, the phosphors used in fluorescent lamps can be blended to
provide any desired color temperature in the range from 2800K to 6000K. Lamps
with color temperatures below 5000K tend to be more yellow/red, lamps rated
between 5000 and 6000K are viewed as white, while lamps above 6000K tend to have
a blue cast.

Lamp/Luminaire Efficacy

The ratio of the light output of a lamp (lumens) to its
active power (watts), expressed as lumens per watt (LPW).

Light Emitting Diode (LED)

A solid-state electronic device formed by a junction of
P-and N-type semiconductor material that emits light when electric current
passes through it. LED commonly refers to either the semiconductor by itself,
i.e. the chip, or the entire lamp package including the chip, electrical leads,
optics and encasement.

Lumen (lm)

A unit measurement of the rate at which a lamp produces
light. A lamp's light output rating expresses the total amount of light emitted
in all directions per unit time. Ratings of initial light output provided by
manufacturers express the total light output after 100 hours of operation.

Luminaire

A complete lighting unit consisting of a lamp or lamps and
the parts designed to distribute the light, to position and protect the
lamp(s), and to connect the lamp(s) to the power supply. (Also referred to as
fixture.)

Lux (lx)

A measure of illuminance in lumens per square meter. One lux
equals 0.093 footcandle.

Power Factor (PF)

The ratio of active power (in watts) to apparent power (in
rms volt-amperes), power factor is a measure of how effectively an electric
load converts power into useful work. Power factor (PF) is calculated using the
equation PF = (active power) / [(rms voltage) x (rms current)]. Phase
displacement and current distortion both reduce power factor. A power factor of
0.9 or greater indicates a high power factor ballast.

Rated Lamp Life

The number of hours at which half of a group of product
samples fail. The rated life is a median value of life expectancy; any lamp or
group of lamps may vary from the published rated life. Rated life is based on
standard test conditions.

Total Harmonic Distortion (THD)

A measure of the degree to which a sinusoidal wave shape is
distorted by harmonics, with higher values of THD indicating greater
distortion.

Uniformity

The degree of variation of illuminance over a given plane.
Greater uniformity means less variation of illuminance. The uniformity ratio of
illuminance is a measure of that variation expressed as either the ratio of the
minimum to the maximum illuminance or the ratio of the minimum to the average
illuminance.

Voltage (V)

The degree of variation of illuminance over a given plane.
Greater uniformity means less variation of illuminance. The uniformity ratio of
illuminance is a measure of that variation expressed as either the ratio of the
minimum to the maximum illuminance or the ratio of the minimum to the average
illuminance.

Watts (W)

The unit for measuring electrical power. It defines the rate
of energy consumption by an electrical device when it is in operation. The
energy cost of operating an electrical device is calculated as its wattage
times the hours of use. In single phase circuits, it is related to volts and
amps by the formula: Volts x Amps x Power Factor = Watts.