| Ambient
Light |
Lighting
throughout a space that produces general illumination. |
|
| Ampere
(amp) |
Unit
to express the flow quantity of electricity. Analogous to
gallons per minute. |
|
| Baffle |
An
accessory that prevents light from producing glare at certain
angles. |
|
| Ballast |
Auxiliary
unit used with HID lamps to provide the power to start
the lamp and regulate the voltage, current & waveform
while it is in use. A ballast is required for each HID
lamp. |
|
| Brightness |
A
negative term associated with glare producing luminaries. |
|
| Bulb |
Layman's
term for "lamp". |
|
| Candela |
The
basic unit of measurement of luminous intensity from a light
source in a specific direction. |
|
| Circuit
Breaker |
A
switching device that can be manually operated that automatically
opens (switches off) when more than the rated current passes
through. Generally rated in amps. A typical residential
circuit breaker is 15 or 20 amps. |
|
| Color
Temperature |
An
expression of light source color or whiteness, stated in
degrees Kelvin. Warmer (more yellow) light has a lower color
temperature and cooler light (more blue) has a higher color
temperature. |
|
| Conductor |
A
metallic material that has low resistance to electrical
flow such as copper. A circuit must have at least 2 conductors. |
|
| Efficacy
(efficiency) |
A
measurement of how many lumens a lamp produces per watt
consumed. |
|
| Fixture |
Layman's
term for "luminaire". |
|
| Floodlighting |
Indiscriminate
lighting of an area usually associated with security or
utility functions. |
|
| Footcandle
(fc) |
A
unit of measurement of luminescence. For reference: an office
desktop typically has 50-75 fc of light falling on it if
lit from overhead fluorescent lamps. A primary focal point
tree in a residential garden should have about 5 fc average
on it |
|
| Fluorescent |
A
low-pressure lamp that has a phosphor coating that transforms
ultraviolet energy into light. Although efficient they are
physically very large. |
 |
| FX |
Term
to describe Lighting Effects - generally used in theatrical
applications. Also the manufacturer of some great lighting
components. |
|
| Gauge |
A
measurement of electrical conductor (wire or cable) size.
The lower the number, the thicker the cable. 8-gauge cable
is twice the size of 12-gauge. |
|
| Glare |
A
negative term describing uncontrolled light that produces
discomfort to the viewer. |
|
| Ground |
A
non-current carrying metallic connection to earth. All 120v
circuits must be grounded - 12v circuits do not. The green
wire on a 120v circuit is typically the ground. |
|
| Ground
Fault Interrupter (GFI) |
A
device that detects abnormal current patterns and shuts
off power. GFI's are always required on outdoor circuits. |
 |
| Halogen |
See
Tungsten-Halogen Lamp. |
|
| Hard
Light |
Light
that produces very high contrast such as the grazing effect |
|
| High
Intensity Discharge (HID) |
A
lamp that produces light when electricity excites different
gases within a pressurized glass envelope. HID lamps include
mercury vapor, metal halide and high-pressure sodium types.
See also Ballasts. |
|
| High
Pressure Sodium Lamp |
An
HID lamp that produces light from sodium vapor, producing
a distinctly yellowish color. Used widely as streetlights. |
|
| Hot |
The
conductor or surface that has voltage present. A hot and
a common or neutral creates an electrical circuit. |
|
| Illuminance |
The
amount of light striking a surface or object, measured in
footcandles or lumens. |
|
| Incandescent
Lamp |
A
lamp that produces light when electricity heats a tungsten
metal filament. |
|
| Lamp |
Technical
term for "bulb". |
 |
| Line
Voltage |
Generally
means 120 volts. |
|
| Low
Pressure Sodium Lamp |
An
HID lamp that produces light from sodium vapor, producing
a distinctly pinkish color. Used for streetlights and security. |
|
| Low-voltage
Lighting |
A
general term given to a system that is powered by a step-down
transformer that reduces a 120v power input to a 12v output. |
|
| Lumen |
The
unit of measurement for the amount of light emitted by a
lamp. One lumen per square foot is one footcandle. |
|
| Luminaire |
Technical
term for "fixture". A complete lighting unit consisting
of a lamp holder, lens and adjustable components. |
 |
| Mercury
Vapor Lamp |
An
HID lamp that produces light by radiation from mercury vapor.
Mercury lamps have a distinct blue-green color and are a
popular moonlight source for very large trees in commercial
environments. Some folks think this type of lamp makes everything
look ghoulish. |
|
| Metal
Halide Lamps |
An
HID lamp that produces light by radiation from metallic
vapors. This type of HID lamp has the most neutral color
rendering effect so it is appropriate for very large-scale
color sensitive uplighting. |
|
| Neutral |
A
conductor that is common to other circuits and carries no
current. |
|
| Ohm |
A
measurement of electrical resistance that causes voltage
loss in circuits. Also, the name of the dead dude that invented
electricity. |
 |
| PAR
Lamp |
Parabolic
aluminized reflector lamp or sealed beam lamp. Generally
used for auto signal or headlights. |
|
| Quality
of Lighting |
A
description of the aesthetic appearance of an illuminated
environment indicating the use and control of light sources. |
|
| Reflectance |
A
measure of the amount of light that strikes a surface that
is reflected. Light-colored smooth surfaces have a high
reflectance. |
|
| Resistance |
Measured in ohms - analogous to friction in hydraulics.
A measurement of the restriction of the free flow of electrons
in electrical conductors. Copper has a low resistance making
it a good conductor - Glass has a high resistance making
it a good insulator. |
|
| Short
Circuit |
An
unwanted flow of current between two conductors causing
the circuit breaker to trip. |
 |
| Shield |
An
opaque unit that shields a light source from direct view
at certain angles. See also Glare |
|
| Task
Lighting |
The
function of providing illumination for specific purposes
such as recreation or utility. |
|
| Transformer |
An
electrical device used to step down 120-volt current to
12-volt current for use on low-voltage lighting systems.
A transformer provides roughly 1/10th of the input power. |
 |
| Tungsten-Halogen
Lamp |
A
type of incandescent lamp containing a tungsten filament
within a pressurized quartz envelope, which is filled with
halogen gas. Also referred to as a quartz or halogen lamp.
The halogen gas recycles the burned off tungsten particles
back onto the filament thereby dramatically extending the
lamp life. Generally smaller and more energy efficient than
120v incandescent lamps. |
|
| Volt
(V) |
Unit
to describe the electrical force that causes current to
flow - analogous to PSI in hydraulics. |
|
| Volt-Ampere
(VA) |
A measurement of consumption. Volts x Amps = Watts. Most
transformers' wattage ratings are expressed in VA. |
|
| Watt
(W) |
Unit
of electrical consumption. See Volt-Ampere. Don't confuse
wattage with light output - light is expressed in lumens
or footcandles. Ex: heat lamps consume a lot of wattage
but produce little light. |
|
