Definitions. Unless specifically defined below, words and phrases used in this section shall be interpreted to have common English usage, to give effect to the purposes set forth in Subsection A above and to provide reasonable application of this section. As used in this section, the following terms shall have the meanings indicated, unless a different meaning clearly appears from the context:
CANDELA
The SI unit of luminous intensity. One candela is one lumen per steradian (lm/sr).
CANDLEPOWER
Luminous intensity expressed in candelas.
CUTOFF ANGLE (OF A LUMINAIRE)
The angle, measured up from nadir, between the vertical axis and the first line of sight at which the bare source is not visible.
DIRECT LIGHT
Light emitted directly from the lamp, off of the reflector or reflector diffuser, or through the refractor or diffuser lens, of a luminaire.
FIXTURE
The assembly that houses the lamp or lamps and can include all or some of the following parts:
(2)
A mounting bracket or pole socket;
(5)
A reflector or mirror; and/or
FLOODLIGHT or SPOTLIGHT
Any light fixture or lamp that incorporates a reflector or a refractor to concentrate light output into a directed beam in a particular direction.
FOOTCANDLE
A unit of illuminance. One footcandle is one lumen per square foot (lm/ft2).
FULLY SHIELDED LIGHTS
Outdoor light fixtures shielded or constructed in such a manner that all light emitted by the fixture, either directly from the lamp or a diffusing element or indirectly by reflection or refraction, is projected below the horizontal plane through the fixture's lowest light emitting part as certified by a photometric test report.
GLARE
The sensation produced by luminances within the visual field that is sufficiently greater than the luminance to which the eyes are adapted to cause annoyance, discomfort or loss in visual performance or visibility.
(1)
BLINDING GLARE
Glare that is so intense that for an appreciable length of time after it has been removed, no object can be seen.
(2)
DIRECT GLARE
Glare resulting from high luminances or insufficiently shielded light sources in the field of view.
(3)
DISABILITY GLARE
The effect of stray light in the eye whereby visibility and visual performance are reduced.
(4)
DISCOMFORT GLARE
Glare that produces discomfort. It does not necessarily interfere with visual performance or visibility.
(5)
REFLECTED GLARE
Glare resulting from reflections of high luminances in polished or glossy surfaces in the field of view.
HEIGHT OF LUMINAIRE
The height of a luminaire shall be the vertical distance from the ground directly below the center line of the luminaire to the lowest direct light-emitting part of the luminaire.
ILLUMINANCE
The quantity of light measured in footcandles or lux.
ILLUMINATION
An alternative term for "illuminance." Commonly used in a qualitative or general sense to designate the act of illuminating or the state of being illuminated.
INDIRECT LIGHT
Direct light that has been reflected or has scattered off of other surfaces.
LAMP
The component of a luminaire that produces light. A generic term for a man-made source of light, i.e., a light bulb.
LIGHT
Radiant energy that is capable of exciting the retina and producing a visual sensation. The visible portion of the electromagnetic spectrum extends from about 380 to 770 nanometers.
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
The shining of light produced by a luminaire beyond the boundaries of the property on which it is located.
LUMEN
A standard 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. One footcandle is one lumen per square foot. For the purposes of this section, the lumen-output values shall be the initial lumen output ratings of a lamp, as specified by the manufacturer of the lamp.
LUMINAIRE, CUTOFF
A luminaire whose light distribution at or above an angle of 90° above nadir does not numerically exceed 25 candelas per 1,000 lamp lumens (2.5%), and does not numerically exceed 100 candelas per 1,000 lamp lumens (10%) at or above a vertical angle 80° above nadir. This applies to all lateral angles around the luminaire.
LUMINAIRE, FULL-CUTOFF
A luminaire whose light distribution at or above an angle of 90° above nadir has zero candela intensity and does not numerically exceed 100 candela per 1,000 lamp lumens (10%) at or above a vertical angle 80° above nadir. This applies to all lateral angles around the luminaire.
LUMINANCE
The physical and measurable quantity corresponding to the brightness of a surface in a specific area from which light is emitted or reflected (e.g., lamp, luminaire, reflecting material). Can be measured in candelas per square meter (cd/m2) or luxes.
LUMINAIRE
A complete lighting unit consisting of one or more lamps together with the fixture, other parts designed to control the light distribution and other mechanical and electrical components.
LUMINOUS FLUX (RADIANT FLUX OR POWER)
The time rate of flow of radiant energy evaluated in terms of a standardized visual response.
LUMINOUS INTENSITY
The luminous flux per unit solid angle in the direction in question. May be expressed in candela or lumens per steradian (lm/sr).
LUX
The standard unit of illuminance. One lux is one lumen per square meter (lm/m2).
NIGHTTIME
The hours between the end of evening civil twilight and the beginning of morning civil twilight. Civil twilight ends in the evening when the center of the sun's disk is 6° below the horizon and begins in the morning when the center of the sun's disk is 6° below the horizon.
OUTDOOR LIGHTING
The nighttime illumination of an outside area or object by any man-made device that produces light by any means.
OUTDOOR LIGHTING, TEMPORARY
Outdoor lighting that is used for a period of less than seven days, with at least 180 days passing before being used again or used annually for a period of 30 days or less.
STERADIAN or SR (UNIT OF SOLID ANGLE)
The solid angle subtended at the center of a sphere by an area on the surface of the sphere equal to the square of the sphere radius.