Crestron Green Light GLPS-HDSW-FT Design Manual page 82

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SELF-LUMINOUS EXIT SIGN: An illumination technology using phosphor-
coated glass tubes filled with radioactive tritium gas. The exit sign uses
no electricity and thus does not need to be hardwired
SEMI-SPECULAR: Term describing the light reflection characteristics of a
material. Some light is reflected directionally, with some amount of
scatter
SHIELDING ANGLE: The angle measured from the ceiling plane to the line
of sight where the bare lamp in a luminaire becomes visible. Higher
shielding angles reduce direct glare. It is the complementary angle of the
cutoff angle.
SPACING CRITERION: A maximum distance that interior fixtures may be
spaced that ensures uniform illumination on the work plane. The
luminaire height above the work plane multiplied by the spacing criterion
equals the center-to-center luminaire spacing
SPECULAR: Mirrored or polished surface. The angle of reflection is equal
to the angle of incidence. This word describes the finish of the material
used in some louvers and reflectors
STARTER: A device used with a ballast to start (preheat) fluorescent
lamps
STROBOSCOPIC EFFECT: Condition where rotating machinery or other
rapidly moving objects appear to be standing still due to the alternating
current supplied to light sources. Sometimes called "strobe effect."
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T12 LAMP: Industry standard for a fluorescent lamp that is 12 one-
eighths, one inch in diameter. Other sizes are T10 and T8 lamps
TANDEM WIRING: A wiring option in which a single ballast is shared by
two or more luminaires. This reduces labor, materials, and energy costs.
Also called "master-slave" wiring.
THERMAL FACTOR: A factor used in lighting calculations that
compensates for the change in light output of a fluorescent lamp due to
a change in bulb wall temperature. It is applied when the lamp-ballast
combination under consideration is different from that used in the
photometric tests.
THREE-WIRE ANALOG POWER DIMMING: Three-wire control is a line-
voltage phase-control dimming method. Along with Hot and Neutral, the
dimming signal is communicated via a third wire called Dimmed Hot. All
three wires are rated Class 1 and can be run within the same conduit.
TRIGGER START: Type of ballast commonly used with 15-watt and 20-
watt straight fluorescent lamps
TROFFER: The term used to refer to a recessed fluorescent light fixture
(combination of trough and coffer)
TUNGSTEN HALOGEN LAMP: A gas-filled tungsten filament incandescent
lamp with a lamp envelope made of quartz to withstand the high
temperature. This lamp contains some halogens (namely iodine,
chlorine, bromine, and fluorine), which slow the evaporation of the
tungsten. Also, commonly called a quartz lamp
Crestron Commercial Lighting Design Guide
TWIN-TUBE: (SEE COMPACT FLUORESCENT)
TWO-WIRE ANALOG POWER DIMMING: Two-wire is a line-voltage phase-
control dimming method. The ballast receives the dimming signal
through the Dimmed Hot wire. Intended for small-scale retrofit
applications, the two-wire control method is often the easiest way to
implement dimming in existing fluorescent fixtures
ULTRA VIOLET (UV): Invisible radiation that is shorter in wavelength and
higher in frequency than visible violet light (literally beyond the violet
light)
UNDERWRITERS' LABORATORIES (UL): An independent organization
whose responsibilities include rigorous testing of electrical products.
When products pass these tests, they can be labeled (and advertised) as
"UL listed." UL tests for product safety only
VANDAL-RESISTANT: Fixtures with rugged housings, break-resistant
type shielding, and tamper-proof screws
VCP: Abbreviation for visual comfort probability. VCP is a rating system
for evaluating direct discomfort glare. This method is a subjective
evaluation of visual comfort expressed as the percent of occupants of a
space who will be bothered by direct glare. VCP allows for several
factors: luminaire luminances at different angles of view, luminaire size,
room size, luminaire mounting height, illuminance, and room surface
reflectivity. VCP tables are often provided as part of photometric reports
VERY HIGH OUTPUT (VHO): A fluorescent lamp that operates at a "very
high" current (1500 mA), producing more light output than a "high
output" lamp (800 mA) or standard output lamp (430 mA)
VA (VOLT-AMPERE): The amount of apparent power in an electrical
circuit. A volt-ampere and a watt are nearly identical for resistive loads,
such as an incandescent lamp. For devices with a power factor less than
one, such as a fluorescent bulb, the volt-ampere rating is higher than the
real power (in watts) consumed by the load.
VOLT: The standard unit of measurement for electrical potential. It
defines the "force" or "pressure" of electricity
VOLTAGE: The difference in electrical potential between two points of an
electrical circuit
WALLWASHER: Describes luminaires that illuminate vertical surfaces.
WATT (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 PF = Watts. (Note: For AC circuits,
PF must be included.)
WORK PLANE: The level at which work is done and at which illuminance
is specified and measured. For office applications, this is typically a
horizontal plane 30 inches above the floor (desk height)
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