Amp: A unit expressing the rate of flow of electric current.

ANSI: American National Standards Institute. The organization that develops guidelines and produces performance standards for the electrical and other industries.

Ballast: A device used to obtain the necessary circuit conditions to start and operate an electric discharge lamp.

  • Electronic: A newer technology that operates lamps at frequencies above 20,000 Hz. Constructed with electronic circuitry.
  • Magnetic: An old technology that uses a "core and coil" (steel plates laminated together and wrapped multiple times with a copper wire) construction. Performs the minimum functions required to start and run the lamp.

Base: The lamp base mechanically holds the lamp in place in the application.

Beam Spread: In any plane, the angle between the two directions in the plane in which the candlepower is equal to a stated percent of the maximum candlepower in the beam.

Bulb: Hard, soft or quartz glass enclosure, which can contain a vacuum, elemental inert gas or metal and a means of light generation (filament or electrodes).

Candela: The unit of measure indicating the luminous intensity of a light source in a specific direction; any given light source will have many different intensities, depending upon the direction considered.

Cathode: Negative electrode.

Color Rendering Index (CRI): The CRI is a measurement of the effect a light source has on the perceived color of objects and surfaces. High CRI light makes virtually all colors look natural and vibrant. Low CRI causes some colors to appear washed out or even to take on a completely different hue.

Color Temperature (Kelvin): CT, which is measured in Kelvin, indicates whether a lamp has a warm, midrange or cool color appearance. "Warm" light sources have a low CT (2000-3000K) and feature more light in the red/orange/yellow range. Light with a higher CT (>5000K) features more blue light and is referred to as "cool".

Compact FluorescentCompact fluorescent lamps employ small diameter tubes that are bent so they begin and end in a single base. This allows them to be produced in a wide variety of configurations, greatly extending the applications for fluorescent lighting.

Current: A measure of the rate of flow of electricity, expressed in amperes (A).

Disposal: When disposing of spent lamps, always consult federal, state, local and/or provincial hazardous waste disposal rules and regulations to ensure proper disposal.

Double Ended: Lamps that have two bases opposite one another for series electrical connections, mechanical mounting and heat dissipation.

Energy: A measure of work done by an electrical system over a given period of time, often expressed in kilowatt-hours (kWh).

Filament: A tungsten wire purposely positioned inside a lamp bulb, that when heated electrically generates radiation in the visible, infrared and ultraviolet ranges. Tungsten material is most often used, as it has great tensile strength, is very durable, and can be heated very near its melting point without evaporating rapidly. Lamp filaments are offered in a variety of designs optimized for specific applications.

Floodlight: A reflector lamp with a relatively wide beam pattern. Also a luminaire consisting of lamp and reflector at fixed distance providing a wide field of illumination.

Fluorescent LightFluorescent light bulbs are low pressure mercury vapor discharge light sources. The electric discharge generates ultra-violet (UV) energy, which is absorbed by a phosphor and converted to visible light.

HalogenHalogen light bulbs are high pressure tungsten filament lamps containing halogen gases. The halogen gases allow the filaments to operate at higher efficacy than incandescent lamps. Halogen lamps also provide brighter, whiter light with better color characteristics, longer service life and improved energy efficiency.

High Intensity Discharge (HID): Lamps in which an arc passing between two electrodes in a pressurized tube causes various metallic additives to vaporize and release large amounts of light. All HID lamps, High Pressure Sodium · Low Pressure Sodium· Mercury Vapor · Metal Halide, offer outstanding energy efficiency and service life. Metal halide lamps also offer good to excellent color rendering index (CRI).

Illuminance: Light arriving at a surface, expressed in lumens per unit area; 1 lumen per square foot equals 1 footcandle, while 1 lumen per square meter equals 1 lux.

Incandescent Lamp: A light source using the principle of incandescence. When an electric current passes through a filament wire (usually tungsten), the heated wire glows. Filaments of standard incandescent lamps are enclosed in a vacuum or gas-filled bulb. They provide low initial cost, good color rendition and excellent optical control.

Instant Start: A light source using the principle of incandescence. When an electric current passes through a filament wire (usually tungsten), the heated wire glows. Filaments of standard incandescent lamps are enclosed in a vacuum or gas-filled bulb. They provide low initial cost, good color rendition and excellent optical control.

Kilowatt (KW): A measure of electrical power equal to 1000 watts.

Lumen: A unit of luminous flux; overall light output; quantity of light, expressed in lumens. For example, a dinner candle provides about 12 lumens and a 60 watt soft white incandescent lamp provides about 840 lumens.

Lux: A unit of illuminance equal to 1 lumen per square meter.

Maximum Overall Length (MOL): The total length of a lamp, from top of bulb to bottom of base.

Operating Position: Some lamps are specified/designed to be operated in certain positions, ie, horizontal or base up.

PAR Lamps: PAR is an abbreviation for parabolic alumninized reflector. PAR Lamps have the outer envelope formed from two pressed glass parts that are fused or sealed together. PAR lamps may be incandescent, halogen, or HID types.

Phosphor: An inorganic chemical compound processed into a powder and deposited on the inner glass surface of fluorescent tubes and some mercury and metal-halide lamps. Phosphors are designed to absorb short wavelength ultraviolet radiation and to transform and emit it as visible light.

Photo Optic: Specialty lamps that employ a variety of technologies to meet the very precise levels of performance required by the entertainment industryscience, medical, and other high-tech fields.

Preheat: A class of fluorescents requiring a starter, which allows the lamp and filaments to be properly haeated before allowing the ballast to supply the correct current flow.

Quartz: A high heat resistant glass-like material manufactured from pure silica sand.

Rapid Start: Rapid start ballasts apply a low filament voltage to preheat the cathodes. Simultaneously, a starting voltage is also applied to strike the arc. When the cathodes are hot enough, the lamp will strike. Rapid start ballasts appear to have a slight turn on delay compared to instant start. They will typically not be able to start lamps reliably under 50'F.

Reflector: A device used to redirect the light by the process of reflection. Photo-Optic reflector lamps utilize ellipsoidal (converging light rays) or parabolic (collimating light rays) reflectors. Dichroic coated reflectors are designed to reflect visible light and pass through unwanted infrared wavelengths.

Single Ended: Lamps having a single lamp base or point of electrical connection.

Spot Light: A luminaire using halogen/incandescent or a high intensity discharge (HID) lamp that produces a narrow beam angle designed to illuminate a specifically defined area. It can also be called a reflector lamp.

Trigger Start: A circuit used to eliminate the starter and start the preheat lamp almost instantyly. In this circuit each electrode is connected to a seperate winding in the ballast so that the electrode is continuously heated.

Ultraviolet RadiationUV Lamps produce radiant energy in the range of about 100-380 nanometers (nm). For practical applications the UV band is broken down as follows:

  • Ozone producing [108-220nm]
  • Bacterial (germicidal) [220-300nm]
  • Erythemel (skin reddening) [280-320nm]
  • "Black" Light [320-400nm]

The International Commission on Illumination (CIE) defines the UV band as:


Voltage: A meausre of the electrical potential, expressed in volts (V). Voltage is the "force" that pushes electrical current through a conductor.


Watts: A unit of electrical power equal to 1 joule per second. Lamps are rated in watts to indicate power consumption. Also see Nominal watts.

Wavelength: Distance between two successive points of a periodic wave; the wavelengths of light are typically expressed in nanometers (nm), or billionths of a meter.