Glossary
Amp; (Ampere): The basic unit of electric current adopted under the System International Unites; "a typical household circuit carries 15 to 50 amps."
Ballast: A device used to operate fluorescent and HID lamps. The ballast provides the necessary starting voltage, while limiting and regulating the lamp current during operation.
Bulb Base: The part of the bulb that is used to set it into place and to make contact with electricity. There are many types and sizes. Most common are E26/27, USA and European standard household size, or medium base as it often is called. The 26 or 27 equates to the diameter measurement in millimeters of the threads of a screw-in bulb base. This type of bulb also includes the PAR 20, PAR 30 and PAR38 types, and a few others. There are MR16 and MR11 type base LED bulbs as well as GU10s.
Candela: Unit of luminous intensity, describing the intensity of a light source in a specific direction.
Compact Fluorescent: A small fluorescent lamp that is often used as an alternative to incandescent lighting. The lamp life is about 10 times longer than incandescent lamps and is 3-4 times more efficacious; also called PL, Twin-Tube, CFL, or BIAX lamps.
Diffuser: A translucent piece of glass or plastic sheet that shields the light source in a fixture. The light transmitted throughout the diffuser will be redirected and scattered.
Fluorescent Lamp: A light source consisting of a tube filled with argon, along with krypton or other inert gas. When electrical current is applied, the resulting arc emits ultraviolet radiation that excites the phosphors inside the lamp wall, causing them to radiate visible light.
HID; (high intensity discharge): Generic term describing mercury vapor, metal halide, high pressure sodium, and (informally) low pressure sodium light sources and luminaries.
Kelvin (K)/ Kelvin Color Temperature: is a measure of the color of a light source relative to a black body at a particular temperature expressed in degrees Kelvin (K). Incandescent lights have a low color temperature (approximately 2800K) and have a red-yellowish tone; daylight has a high color temperature (approximately 6000K) and appears bluish (the most popular fluorescent light, Cool White, is rated at 4100K). Lamps with color temperatures below 5000K tend to be more yellows/reds, lamps rated between 5000 and 6000K are viewed as white, while lamps above 6000K tend to have a blue cast.
Lumens: The unit of luminous flux in the International System, equal to the amount of light given out through a solid angle by a source of one candela intensity radiating equally in all directions used to measure light bulbs as stand alone light sources. Lighting fixtures are measured by lux output which is lumens per square meter.
Luminance: A photometric term that quantifies brightness of a light source or of an illuminated surface that reflects light. It is expressed as foot lamberts (English units) or candelas per square meter (Metric units).
L.E.D.: LED means light emitting diode. LED is a solid state device and do not require heating of a filament to create light. Rather, electricity is passed through a chemical compound that is excited and as a result, generates light.
LEDs are not bulbs or lamps in the true sense of the word and application. LEDs require a lot of work to make them ready to be used by the consumer. They need to be placed on a circuit board or other material which will allow electricity to pass through it at a specific voltage and current, and with components required to operate them at specific voltages such as 12vdc, 24vdc or 120vac. They do not come ready to plug into a 12volt or 120 volt power source.
MR: (Multifaceted Reflector); exp. MR-16: A low-voltage quartz reflector lamp, only 2" in diameter. Typically the lamp and reflector is one unit, which directs a sharp, precise beam of light. PAR LAMP: A parabolic aluminized reflector lamp. An incandescent, metal halide or compact fluorescent lamp used to redirect light from the source using a parabolic reflector. Lamps are available with flood or spot distributions.
Photocell: A light sensing device used to control luminaries and dimmers in response to detected light levels.
Retrofit: Refers to upgrading a fixture, room, or building by installing new parts or equipment.
