Outdoor Lighting Glossary

ANSI (American National Standards Institute) - Organization for developing voluntary guidelines and performance standards for the electrical industry, as well as for other fields.

Average Rated Life - This term is defined as the time in hours when 50% of a group of lamps have failed, having been run at nominal lamp voltage and current. Fluorescent lamps are tested 3 hours at a time while HID (high-intensity discharge) lamps are tested 10 hours at a time when tested by manufacturers. Each lamp has its own mortality curve which depicts its average rated life.

Baffles (Fixture) - Shield, plate, or other mechanism that governs the flow of light from a fixture.

Ballast - Electric-discharge lamps start with a burst of electricity, then need lower amounts to continue operating. The proper circuit conditions, ie., voltage, current, and waveform, are maintained by the ballast. Fluorescent and HID light sources require a ballast for proper operation.

Burning Position - This is the position in which the lamp was manufactured to operate for performance and safety. They include:
BD - Base Down (metal base at the bottom, glass up)
BU - Base Up (metal base at the top, glass hanging down)
HBU - Base Up +/- 90 degrees (base up or horizontal position)
HOR - Horizontal Burn (metal base parallel to the ground)
U - Universal Burn (bulb can be operated in any position)

Color Rendering Index (CRI) - A light source's capacity for producing color in objects. The index is a scale from 0 to 100, 100 being the best in producing vibrant color.

Color Temperature - Originally, a term describing the "whiteness" of incandescent light. Color temperature directly relates to the physical temperature of the filament in incandescent lamps, so the Kelvin (K), or absolute, temperature scale is employed when describing it. A higher color temperature (K) describes a visually cooler, bluer light source. The term "chromaticity" has been used of late in its stead.

Cool White - Refers to the color tone of light produced by a lamp or a specific color temperature. These days, Cool White is the most widely used and cheapest fluorescent lamp color. Its name is derived from the cool atmosphere created when used. Modern, efficient, and business-like, it is popular all over, from offices and supermarkets to classrooms and factories.

Correlated Color Temperature (CCT) - Used for discharge lamps with no hot filament involved, to express that the light appears as though the discharge lamp were operating at a given color temperature. Typically, CCT measures the "warmth" or "coolness" of a light source appearance using the Kelvin (K) scale.

Compact Fluorescent Lamp (CFL) - A fluorescent-type bulb with the ability to be used in an incandescent fixture, while maintaining the efficiency and qualities of a normal fluorescent bulb. Compact Fluorescent Lamps usually save 75% in electricity while giving comparable light levels. Compact Fluorescent bulbs require a special adapter or ballast if they do not have one built in. Their average lifespan is about 10,000 hours.

Daylight - Daylight refers to the color tone or appearance of light emitted by a lamp making a specific color temperature. The blue-and-white tint to this lamp is similar to daylight. It creates an inviting and very cool environment, while giving a store or office a blue-white radiance. It is often used over white goods.

Economic Life - Referring to a significant number of lamps, it is the number of hours they will burn before it's economically and aesthetically best to replace the group of lamps (typically 60% to 75% of rated life).

Efficacy - The efficacy is defined as the efficiency of a lamp in terms of lumens per watt (LPW or lm/W).

Enclosed Fixtures - Fixtures with a lens protecting the bulb from elements.

Energy - Measure of work by an electrical system over a given period, usually denoted with the kilowatt-hour (kWh).

Filament - Tungsten wire placed in a bulb that generates light when hot.

Fluorescent Lamp - This is a high-efficiency lamp using an electric discharge through low-pressure mercury vapor and produces ultra-violet (UV) energy. The UV shakes up phosphor materials applied in a thin layer on the interior of the glass tube that is the lamp itself. The phosphors do the work of transforming the UV into visible light.

Footcandle (fc) - A footcandle is a unit of illumination or light falling on a surface. One footcandle equals 1 lumen per square foot.

Frost - Refers to the glass of the lamp with a slightly opaque white inner coating.

Four-Pin Compact Fluorescent Lamps - These types of lamps do not have any starter built into their base. Because of this, the ballast has the starting circuit. Traditionally, four-pin lamps are designed to work with electronic ballasts.

Full Spectrum - Simply put, this bulb will reproduce the full color spectrum of natural light.

Glare - Refers to the excessive brightness that may be caused by viewing a light source directly or indirectly.

Halogen Lamp - This is the abbreviated name for a tungsten-halogen lamp. These lamps are high-pressure incandescent lamps that operate at higher temperatures and higher efficacies enabled by the use of halogen gases such as iodine or bromine. A high-temperature chemical reaction, involving tungsten and the halogen gas, recycles evaporated particles of tungsten back onto the filament surface.

High-Intensity Discharge (HID) - A generic term for a mercury vapor, metal halide, or high-pressure sodium lamp. They are different from incandescent lamps because there is no filament; rather, they contain gas which, when exposed to an electric charge, produces light. HID lamps require a ballast, which governs the electricity that flows into the lamp.

High-Pressure Sodium - HID bulbs that contain a sodium gas and produce a yellow/orange light. Very bright, lasting up to 24,000 hours.

Incandescent - These light bulbs are likely the most frequently used bulbs in your home. The incandescent bulb operates using a filament, which glows very brightly when electricity flows to it.

Infrared Radiation - This radiation is electromagnetic energy radiated between wavelengths of about 770 to 1106 nanometers. Invisible to the human eye, it can still be sensed as heat by the skin.

Instant Start - A lamp-starting method without preheating the lamp filaments while still starting with high-voltage input. Some rapid-start lamps are designed so that they may be started instantly.

Instant-Start Lamp - This is a fluorescent lamp with a single pin at both ends. The lamp is lit using high voltage without filament heating.

Kelvin Temperature - See Color Temperature

Lamp - This word is used to refer to the complete light source package, including the inner parts as well as the outer bulb or tube. "Lamp", of course, is also commonly used to refer to a type of small fixture such as a table lamp.

Lamp Watts - The power supplied to the lamp to power it.

LED - Light-Emitting Diode.

Low-Pressure Sodium - HID bulbs with sodium gas. They produce a yellowish light. Their average life span is 18,000 hours. Generally they are used for security areas, as they perform very well with security cameras, indoors and out.

Lumens Per Watt - An efficiency rating that measures the amount of white light per watt emitted from a lamp.

Luminaire - Lighting unit consisting of a lamp (or lamps), with parts designed to distribute the light, position and protect lamps, and connect them to the power supply.

Lumen Maintenance - A rating which expresses the ability of a lamp to emit its lumens-per-watt ratio for a given portion of its life.

Lumen Efficacy - The light output of a source divided by the total power input to that source. It is expressed in lumens per watt.

Maximum Overall Length (M.O.L.) - A front-to-back measurement of a lamp in inches or millimeters.

Mean Lumens - This figure expresses the average light output of a lamp over its rated life. For fluorescent and metal halide lamps, the mean lumen ratings are measured at 40% of rated lamp life. For mercury, high-pressure sodium, and incandescent lamps, mean lumen ratings are measured at 50% of rated lamp life.

Mercury Vapor Lamp - High-intensity discharge light source that operates at a relatively high pressure (about 1 atmosphere) and temperature. Most of the light is produced by radiation from excited mercury vapor. Some lamps have phosphor coatings to add additional light and improve color rendering.

Metal Halide Lamp - HID bulbs that make a blue-white light, very efficient and long-lasting. Their average life span is 20,000 hours.

NFPA - National Fire Prevention Agency.

Neodymium - A rare earth element used in glass to filter excess yellow spectrum to which our eyes are very sensitive.

Parabolic Aluminized Reflector (PAR) Lamp - Incandescent lamp made from heavy glass that controls its light beam using reflector and lens. PAR lamps are usually water-resistant.

Photocontrol (Photocell) - A mechanism that detects light levels, controlling the electrical operation of a light fixture when changes occur.

Preheat Lamp - Fluorescent lamp with a filament that must be heated by a starter before the arc is created. Generally operated with electromagnetic ballasts.

Programmed Rapid Start - Starting method which preheats the lamp filaments, without allowing the lamp to ignite. Then the open circuit voltage is applied (OCV) to start the lamp. A half- to one-second delay may occur after turning on the lamps while it preheats. This kind of start keeps lamp end blackening to a minimum and improves performance, particularly in applications where lamps are switched on and off often.

Pulse-Start Lamp - A specially designed metal halide lamp that uses a ballast with igniter for starting.

Rapid Start - A lamp-starting method in which lamp filaments are heated while open circuit voltage (OCV) is applied to facilitate lamp ignition.

Rapid-Start Lamp - This is a fluorescent lamp with a pair of pins at each end that are connected to the filament. Filaments are heated by the ballast to help starting. There are rapid-start lamps that start instantly without filament heat.

Rated Life - See Average Rated Life

Reflector Lamp - This type of incandescent, compact fluorescent, or HID lamp has a built-in reflecting surface. Incandescent and HID versions are made from blow-molded soft or hard glass. CFL versions are made of one piece or are designed so that the inner lamp can be replaced.

Restart or Restrike Time - This is the time between return of power and lamp ignition after an interruption.

Restrike - To re-ignite the arc of a HID lamp.

Retrofit - Self-ballasted replacement lamp which converts light sources to either change light characteristics or reduce the consumption of energy.

Shroud - Glass cylinder surrounding the arc tube in open-fixture-rated metal halide lamps. Designed to contain hot arc tube particles and glass bulb breakage in the event of rupture. Reduces the risk of using metal halide lamps in open fixtures.

Starting Temperature - The lowest outside temperature at which a fluorescent tube will operate. May be determined by the ballast or specific qualities of the lamp.

Troffer - Inverted metal trough suspended from the ceiling for fluorescent lighting tubes.

Two-Pin Compact Fluorescent Lamps - Type of lamps that have the glow bottle starter built into the base of the lamp. Traditionally, two-pin lamps are designed to work with electromagnetic ballasts.

UL (Underwriters' Laboratories, Inc.) - Sets safety standards for building materials, electrical appliances, and other products.

Voltage - Measurement for the electromotive force, or the pressure of electricity.

Warm White - Reference to the color tone or appearance of light produced by a lamp for a specific color temperature. The color of the light from this lamp makes a factory, office, or store seem warmer and friendlier. Together with the "white" lamp, this is the most efficient of all fluorescent colors. It is a good choice to blend with incandescent bulbs.

Warm-Up Time - Time between ignition to the point when a lamp emits 90% of light output.

Watt - A unit of electrical power. are rated in watts to indicate their power consumption. Power consumed over time equals the electrical energy used.