[Ord. 1631, 8/14/2000, Section XII]
CANDELA
The SI unit of luminous intensity. One candela is one lumen per steradian (lm/sr).
CANDLEPOWER
Luminous intensity expressed in candelas.
CUTOFF ANGLE
The vertical angle measured above nadir at which the light source from a luminaire is no longer visible.
CUTOFF LUMINAIRE
A luminaire light distribution is designed as cutoff when the candlepower per 1,000 lamp lumens does not numerically exceed 25 (2.5%) at an angle of 90° above nadir (horizontal) and 100 (10%) at a vertical angle of 80° above nadir.
FIXTURE
The assembly that holds the lamp along with any globe, shade, or other covering surrounding the lamp.
FLOODLIGHT OR SPOTLIGHT
Any lamp or luminaire that by its design concentrates light output into a directional beam.
FOOTCANDLE (FC)
A unit of illuminance. One footcandle is one lumen per square foot (lm/ft2).
GLARE
A subjective term used to describe any illumination from a light source that strikes the viewer's eye causing annoyance, discomfort, or loss in visual performance or visibility.
HEIGHT OF LUMINAIRE
It is measured as the vertical distance between the top of the luminaire and the ground directly below the luminaire.
ILLUMINANCE
The areal density of the luminous flux incident at a point on a surface. It is measured in footcandles.
ILLUMINATION
A non-technical term designating the state of emitting visible light or having visible light reflected off an object.
LAMP
The component of a luminaire that produces the actual light.
LIGHT
Radiant energy that is capable of exciting the retina and producing a visual sensation.
LIGHT LOSS FACTOR (LLF)
The ratio of illuminance for a given area to the value that would occur if lamps operated at their initial rated lumen output and if no system variation or depreciation had occurred.
LIGHT TRESPASS
A subjective perception of undesirable illumination including the following examples:
LIGHTING SYSTEM
A functionally related group of interacting luminaires used to illuminate a specific area.
LUMEN
SI unit of luminous flux. Photometrically, it is the luminous flux emitted within a unit solid angle (one steradian) by a point source having a uniform luminous intensity of one candela.
LUMINAIRE
A complete lighting unit consisting of a light source(s) together with all parts designed to control the light distribution, and any other mechanical, electrical, or decorative parts.
LUMINANCE
The emitted or reflected light from a surface the amount of which causes perceived brightness. The unit of luminance is the candela per square meter (cd/m2).
LUMINOUS FLUX
Radiant flux (radiant power); the time rate of flow of radiant energy evaluated in terms of a standardized visual response.
LUMINOUS INTENSITY
The luminous flux per unit sold angle in the direction in question. Can be expressed in candelas or lumens per steradian (lm/sr).
MAINTAINED AVERAGE ILLUMINATION
The average of all points on the surface of the illuminated area.
MOTION SENSOR DEVICE
A device that switches lighting on and off in response to the motion.
PARK
A tract of land reserved for public use as playgrounds, trails, paths, natural areas, or recreational areas and other public areas.
SECURITY LIGHTING
Lighting designed for and expressly used to deter criminal activity by illuminating a specific area at nighttime.