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XII.7
Glossary
Lamp
The term used to refer to the complete light
source package, including the inner parts as
well as the outer bulb or tube. “Lamp”, of course,
is also commonly used to refer to a type of
small light fixture such as a table lamp.
Lamp Current Crest Factor
Ratio of peak lamp current to RMS or average
lamp operating current .
Lamp Height
Referenced by IEC as Dimension C. Also referred
to as “Base Face to Top of Lamp”.
Lamp Types
Filament lamps: Incandescent , Halogen,
Halogen-IR.
Discharge Lamps: Fluorescent , HID (High
Intensity Discharge)
HID Lamps: Mercury, HPS (High Pressure
Sodium), MH (Metal Halide) and CMH (Ceramic
Metal Halide)
LED Lamps
Lamp Width
Referenced by IEC as Dimension A.
Leadframe
A metallic frame used for mounting and
connecting LED chips. The leadframe functions
as the electrical leads of the device.
Lens
A transparent or semi-transparent element
which controls the distribution of light by
redirecting individual rays. Luminaires often
have lenses in addition to reflectors.
Life
(See RATED LAMP LIFE).
Light
Radiant energy that can be sensed or seen
by the human eye. Visible light is measured in
lumens.
Light Center Length (L.C.L.)
The distance between the center of the
filament , or arc tube, and a reference plane
- usually the bottom of the lamp base. Refer
to the following chart for reference plane
locations.
Light Emitting Diode (LED)
A solid that directly converts electrical impulses
into light . Most white light LEDs incorporate
phosphors to change the colour characteristics
of the emitted light .
Lighting Industry Federation (LIF) Code
For Stage & Studio lamps, these are assigned
by the Lighting Federation of London U.K.
They ensure electrical and mechanical
interchangeability of similarly coded lamps.
LIF codes are divided into groups according to
the primary application of the lamps.
Light Loss Factor
The product of all factors that contribute
to lowering the illumination level including
reflector degradation, dirt , lamp depreciation
over time, voltage fluctuations, etc.
Light Meter
(See ILLUMINANCE METER)
Light Pollution
Light that is directed to areas where it is not
needed, and thereby interferes with some visual
act . Light pollution directed or reflected into the
sky creates a “dome” of wasted light and makes
it difficult to see stars above cities.
Light Trespass (Spill Light)
Light that is not aimed properly or shielded
effectively can spill out at into areas that don’t
want it: it can be directed towards drivers,
pedestrians or neighbors. It is distracting and
annoying and can sometimes be disabling.
Lucalox™
The GE brand name for high-pressure sodium
lamps.
Lumens
A measure of the luminous flux or quantity of
light emitted by a source. For example, a dinner
candle provides about 12 lumens. A 60-watt
Soft White incandescent lamp provides about
840 lumens.
Lumen Depreciation, Lumen Maintenance
A measure of how well a lamp maintains its
light output over time. It may be expressed
numerically or as a graph of light output vs.
time. The “mean lumens” of a lamp is the
lumens at 40% of rated life (50% for HPS lamp).
Lumens Per Watt (LPW)
A ratio expressing the luminous efficacy of a
lightsource.
Typical lamp efficacies:
Edison’s first lamp
1.4 LPW
Incandescent lamps
10-20
Halogen lamps
15-30
Fluorescent lamps
35-105
Mercury lamps
50-60
Metal halide lamps
60-120
High-pressure sodium lamps
60-140
Note: The values above for discharge lamps
do not include the effect of the ballasts,
which must be used with those lamps. Taking
ballast losses into account reduces “system”
or lamp ballast efficacies typically by 10-20%
depending upon the type of ballast used.
Luminaire
A complete lighting unit consisting of a lamp (or
lamps), ballast (or ballasts) as required together
with the parts designed to distribute the light ,
position and protect the lamps and connect
them to the power supply. A luminaire is often
referred to as a fixture.
Luminaire Efficiency
The ratio of total lumens emitted by a luminaire
to those emitted by the lamp or lamps used in
that luminaire. Also commonly referred to as
‘Light Output Ratio’ or LOR.
Base type
L.C.L Reference Plane
Location
All screw bases
(except Mini-Can)
Bottom of base contact
Mini-Can
Where diameter of
ceramic base insulator is
.531 inches
3-Contact Medium Bottom of base contact
Mogul Medium
Prefocus
Top of base fins
Mogul Prefocus
Top of base fins
Medium BiPost
Base end of bulb (Glass
lamps)
Bottom of ceramic base
(Quartz lamps)
Mogul BiPost
Shoulder of posts (Glass
lamps)
Bottom of ceramic base
(Quartz lamps)
2-Pin Prefocus
Bottom of ceramic base
S.C. or D.C. Bayonet
Candelabra
Top of base pins
Medium Bayonet
Top of base pins
S.C. or D.C. Prefocus Plane of locating bases on
prefocus collar
Medium 2-Pin
Bottom of metal base shell