Property abutting the lot being developed as well as properties that are separated by a street, road, or right-of-way.

The unit that describes the intensity of a light source in a specified direction and is equal to one lumen per steradian (lm/sr).

A luminaire light distribution where the candela per 1,000 lamp lumens does not numerically exceed 25 (2.5%) at an angle of 90° above the nadir and 100 (10%) at a vertical angle of 80° above the nadir.

Any light fixture that emits its light below 45° when measured from 0° to 180° vertical. Dark sky cutoff fixtures keep most of their light from reaching the night sky (i.e., emit no more than 2% of the light above the horizontal plane) and also minimize ground reflection and reduce light scatter beyond the property line.

Any light fixture that emits its light below 90° when measured from 0° to 180° vertical. Dark sky fixtures keep most of their light from reaching the night sky (i.e., emit no more than 2% of light above the horizontal plane).

Anything that is used to shade a light fixture so that it behaves as a dark sky fixture. These include, but are not limited to, fixtures outfitted with caps or housings or installed under canopies, building overhangs, and roof eaves or shaded by other structures, objects, or devices.

Anything that is used to shield a light fixture so that it behaves as a dark sky cutoff fixture. These include but are not limited to, fixtures outfitted with caps or housings or installed under canopies, building overhangs, and roof eaves or shielded by other structures, objects, or devices.

Light emitted directly from the lamp, off the reflector or diffuser of a luminaire.

Glare that reduces visual performance due to light scattered in the eye, reducing the contrast of the image.

A measurement of the ratio of light produced by a light source to the electrical power used to produce that light, expressed in lumens per watt.

Illumination as required by civil officers, agents, and officials to perform their duties to maintain public health, safety, and welfare.

The assembly that holds the lamp (bulb) in a lighting system. It includes the elements designed to give light output control, such as a reflector (mirror) or refractor (lens), the ballast, housing, and the attachment parts.

A light designed to flood a well-defined area with light, with a reflector or optical assembly that concentrates the light output in a particular direction or spot.

A lamp used for indoor retail and office uses and occasionally in outdoor area lighting. Fluorescent lamps are also available in the so-called "compact" styles. Advantages include low initial costs for lamps and fixtures compared with the lamp types below, low life cycle costs and high efficiency compared to incandescent, no warm-up period, good color rendition, and long lifetimes. Disadvantages include higher initial costs compared to incandescent lamps, large lamp size, low efficiency (compared to HID lamps), poor output maintenance, attraction of insects, and potentially hazardous mercury waste.

The basic unit of luminance (the amount of light falling on a surface). Footcandle measurement is taken with a light meter. One foot-candle is equivalent to the luminance produced on one square foot of surface area by a source of one standard candle at a distance of one foot. Horizontal footcandles measure the illumination striking a horizontal plane. Vertical footcandles measure the illumination striking a vertical plane.

A shielded fixture that directs all light towards the ground by preventing all transmission of light above a horizontal line as specified by the Illumination Engineering Society, i.e., distribution where zero candela intensity occurs at an angle of 90° above nadir and all greater angles from nadir, and prevents the direct image of a bright source. Additionally, the candela per 1,000 lamp lumens does not numerically exceed 100 (10%) at a vertical angle of 80° above the nadir.

A bright source that causes the eye to be drawn continually toward the bright image or when the brightness of the source prevents the viewer from adequately viewing the intended target.

High-intensity discharge lighting, a family of bulb types, including mercury vapor, metal halide, or high-pressure or low-pressure sodium, which glows when an electric current is passed through a gas mixture inside the bulb.

Most widely used HID lamps for roadway and parking lot lighting. Advantages include a long lifetime, a wide variety of moderate to high luminous output lamps, high efficiency and good maintenance, moderate color rendition, and wide availability and moderate cost of lamps and luminaires. Disadvantages include poorer color rendition than metal halide, fluorescent and incandescent, poorer output efficiency than low-pressure sodium, and potentially hazardous mercury waste.

Festoon-type lights, limited to small, individual low-wattage bulbs on a string.

Lamp commonly used for the majority of residential lighting, both indoor and outdoor. Incandescent lamps are widely available in a huge variety of lamp styles of low to moderate luminous output. They are commonly used in applications where such low outputs are needed and where the lighting is often switched off and on. Advantages include low capital cost for lamps and luminaires, wide availability, a wide variety of both lamp and fixture types, lack of a warm-up period, and lack of hazardous wastes. Disadvantages include short lifetimes, low efficiency with resultant high per-lumen energy use and life cycle cost, the attraction of insects, and high heat production.

Direct light that has been reflected or scattered.

The attachment or assembly of any outdoor lighting fixture and its fixing in place, whether or not connected to a power source.

The upward emitting of stray light which may illuminate clouds, dust, and other airborne matter and may obscure the night sky.

The lamp or enclosing bulb or reflective enclosure.

Any artificial light greater than 0.10 footcandle falling outside the boundaries of the property upon which the outdoor luminaire is installed. Light trespass occurs when neighbors of an illuminated space are affected by the lighting system's inability to contain its light within the area intended.

A HID lamp popular in some American cities, the light produced by LPS lamps is nearly monochromatic at a wavelength near 589 nanometers. Though the eye is very sensitive to this wavelength (leading to the high efficiency of LPS), the eye cannot distinguish colors when LPS light is the only source available. Low-pressure sodium lighting is favored where energy consumption and costs are a major concern and where color discrimination is either not needed or is supplied by other lighting. Advantages include the highest luminous efficiency and lowest energy use, low glare associated with the large lamps, good visibility, low scattering, minimal effects on insects and other wildlife, and lack of hazardous mercury wastes. Disadvantages include the lack of color rendition, shorter lamp lifetime, higher lamp replacement costs compared to HPS, and large lamp size in the higher output lamps.

The unit of measurement of the quantity of light produced by a lamp or emitted from a luminaire. The lumen quantifies the amount of light energy produced by a lamp at the lamp, not by the energy input, which is indicated by the wattage. For example, a one-hundred-watt incandescent light produces 1,800 lumens, while a seventy-watt high-pressure sodium lamp produces 6,000 lumens. The manufacturer lists the lumen output on the packaging.

A complete lighting unit often referred to as a "light fixture." A luminaire consists of the lamp or light source, optical reflector and housing, and electrical components for safely starting and operating the lamp or light source.

The first widely used HID lamps. Though highly efficient and long-lived compared to the incandescent lighting technology they displaced, they have many disadvantages compared to other lighting sources available today, including low luminous efficiency, poor color rendition, and high ultraviolet output. Mercury vapor lamps have now been almost completely replaced in new applications by the more efficient metal halide and high-pressure sodium lamps.

A HID lamp, similar to mercury vapor lamps, but with the addition of small amounts of various metallic halides, such as scandium, sodium, dysprosium, holmium, and thulium iodide. The many different varieties of metal halide lamps give a wide variety of slightly different color characteristics, though generally, they are white or blue/white sources. Besides a relatively steep fall-off in intensity with time (compared to high-pressure sodium; see below), many metal halide lamps also change their color as they age. Metal halide lamps are very commonly used in commercial outdoor lighting where white light with good color rendition is required or desired, such as car dealer display lots, sports lighting, and service station canopies. Advantages include a wide variety of moderate to high luminous output lamps, high efficiency compared to incandescent and mercury vapor, and good color rendition. Disadvantages include lower efficiency and output maintenance compared to high- and low-pressure sodium, shorter lamp lifetime compared to high-pressure sodium, color changes, ultraviolet output if not adequately filtered, and potentially hazardous mercury waste.

Any device that turns a light fixture on when it detects motion and off when motion stops.

The point directly below the luminaire.

A luminaire light distribution where there is no candela limitation in the zone above the maximum candela.

The nighttime illumination of an outside area or object by a device that produces light by any means.

Any outdoor electrically powered luminaire, permanently installed or portable, used for illumination, decoration, or advertisement. Such devices shall include general ambient lighting, street and area luminaires, decorative lighting, accent or feature lighting, as well as searchlights, spotlights, and floodlights, any of which is for use at or on:

Luminaire light distribution where the candela per 1,000 lamp lumens does not numerically exceed 50 (5%) at an angle of 90° above the nadir and 200 (20%) at a vertical angle of 80° above the nadir.

The result of scattered light in the atmosphere, which means the haze or glow of light that reduces the ability to view the nighttime sky.

The basic international system unit of measurement of a solid angle in a sphere. One steradian is the solid angle made at the center of a sphere by an area on the surface of the sphere equal to the square of the sphere's radius.

Any device that can be manually controlled by a person to turn a light fixture on and off. For this article, switches include motion sensors, but switches do not include light sensors or timers.

Illumination as required by citizens to carry out legally approved activities for durations as specified in the permits for those activities. These include, but are not limited to, activities such as nighttime agricultural operations, construction work lighting, and seasonal decorations, but in no case shall such temporary lighting continue for more than a period of three (3) months without an exemption granted by the Town of Denton.