Home > Technical > Glossary
This information is in alphabetical order. Click on the initial of the subject you are interested in, for example, "F" for fixture. You may have to scroll to see the entry you want.
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
AMBIENT LIGHTING - general lighting that usually lights up an entire space
ANSI (American National Standards Institute) - Group that generates product performance standards for many U.S. industries.
ARC - Intense luminous discharge formed from passage of electric current across a space between electrodes.
ARC TUBE - Completely sealed quartz or ceramic tube where an electrical arc occurs and generates light.
AVERAGE RATED LIFE - The rated life of a lamp signifies the time at which 50% of a large quantity of these lamps will have burned out. That means that 50% of these lamps will burn out BEFORE the rated life and 50% will burn out AFTER the rated life. The rated life does NOT mean that every one of the lamps will last at least that long. Also, please note that the Actual Life of a Lamp = the Rated Life of that Lamp x (Rated Voltage/Operating Voltage) raised to the 12th power. For example, the Actual Life of a certain Lamp that is designed to be used with 130 volts is equal to the Rated Life of that Lamp (let's say 1000 hours) x (130 volts/ 120 volts) raised to the 12th power. The Actual Life of this Lamp is, therefore, equal to (1000 hours) x (1.083) raised to the twelfth power = (1000 hours) x (2.61) = 2610 hours. That means that an incandescent lamp that has a rated life of 1000 hours and is designed to be used with 130 volts BUT is used with 120 volts instead will have an "Actual Life" of 2610 hours.
BEAM SPREAD - a measure of the spread of light from a reflectorized light source, a special-shaped lamp with a reflective coating inside the bulb to direct the light forward. The beam spread may be very narrow (narrow spot), very wide (wide flood), or something in-between (narrow flood, for example). Examples of "reflectorized light sources" are MR11, MR16, PAR20, PAR30, PAR38, R40, ER30, and BR30 lamps.
BALLAST - an electrical device used with fluorescent or HID (high intensity discharge) lamps to supply sufficient voltage to start and operate the lamp but then to limit the current during operation.
BALLAST LOSSES - Power which is supplied to the ballast but not converted into light energy.
BURNING POSITION - Position that lamps are designed to operate.
CCANDLEA (CD) The unit of measurement of luminous intensity of a light source in a given direction.
CAPACITOR - Device in ballast that stores electrical energy.
CONSTANT WATTAGE AUTOTRANSFORMER (CWA) BALLAST - Auto transformer lead ballast circuit using a capacitor in series with the lamp; compared to other ballasts, the CWA regulates over a wider input voltage range, holding lamp wattage to a narrow range.
COLOR RENDERING INDEX (CRI) - a measure of a lamp’s ability to render colors accurately. The scale ranges from 1 (low pressure sodium) to 100 (the sun). A CRI of 85 is considered to be very good.
COLOR TEMPERATURE - a measure of the color appearance of a light source which helps describe the apparent "warmth" (reddish) or "coolness" (bluish) of that light source. Generally, light sources below 3200K are considered "warm;" while those above 4000K are considered "cool" light sources. The color temperature of a lamp has nothing to do with how hot the lamp will get or how much heat is given off by the lamp. The letter, K, stands for Kelvin.
DICHROIC COATING - Film that reflects visible light and transmits infrared light. Reflector lamps with dichroic coatings, such as most MR16s provide a cooler beam because most of the heat goes out the back. Dichroic PAR lamps are often called “cool beam.”
DIRECT CURRENT - electric current without alterations. DC current is usually supplied by a battery, a transformer, or photovoltaic cells.
DISCHARGE LAMP - Light-producing device that depends on electric arc, rather than filament, to create illumination.
ECONOMIC LIFE - Number of hrs. a group of lamps will burn before it's ergonomically advisable to group re-lamp (typically 60%-75% of rated life).
EFFICACY - a measure used to compare light output to energy consumption. Efficacy is measured in lumens per watt. A 100-watt light source producing 1750 lumens of light has an efficacy (efficiency) of 17.5 lumens per watt (L/W).
ELECTRONIC BALLAST - Ballast that, with aid of electronic components, transforms current at high frequency to operate discharge lamps.
EMI (ELECTROMAGNETIC INTERFERENCE) - Electrical interference with radio communications, defined by Federal Communications Commission (FCC).
ETL - Independent electrical testing laboratory which performs ballast testing.
FILAMENT - The tightly coiled tungsten wire of an incandescent lamp; glows to produce light when electricity flows through it.
FOOT CANDLES - Measure of light level on a surface which is being illuminated.
GENERAL SERVICE (A) BULBS - General service bulbs are inexpensive and are readily available in a variety of wattages and shapes. They produce a yellowish white light that is emitted in all directions. Available in either clear or frosted versions.
GLARE - direct glare is caused by light coming directly to the eye from a light source. Indirect glare is light reflected from a surface in the direction of the eye. Both can harm vision and cause visual discomfort or disability.
HALOGEN LAMP - Incandescent lamp with halogen gas fill and a quartz glass capsule. The quartz capsule requires a separate glass shield or enclosure. Due to the halogen cycle, halogen lamps operate at higher internal temperatures, producing more lumens per watt and brighter light than ordinary incandescent; lamp life is also extended. Halogen lamps include A, MB, T, PAR and MR types.
HID - High Intensity Discharge; includes metal halide, mercury vapor and high pressure sodium.
HIGH POWER FACTOR BALLAST - Ballast designed so that input power factor isn't less than 90% when ballast is operated at center-rated voltage using proper reference lamp.
HIGH REACTANCE AUTOTRANSFORMER (HX) BALLAST - Autotransformer lag circuit that uses magnetic shunt path between primary and secondary coils to control reactance.
IGNITER - Electronic device that provides, by itself or in combination with other circuit components, the appropriate electrical conditions to start a discharge lamp.
INFRARED RADIATION - a type of invisible radiation for which the wavelengths are longer and frequency lower than those for visible radiation.
INITIAL LUMENS - Lumen level of lamp after it has been operating 100 hrs.
INPUT VOLTAGE - Voltage, provided by power line/power supply, which the ballast uses to provide proper level to power lamps.
INSTANT START - refers to fluorescent lamps that start instantly without pre-heating the cathodes and without the need for starters.
NO ENTRIES
KELVIN - Scientific unit of temperature. Color temperature is measured on the Kelvin scale.
LAMP VOLTAGE - Voltage which lamps operate when they are fully warmed up.
LED : light emitting diode. A small electronic device that lights up when electricity is passed through it. LEDs are quite energy-efficient and have very long lives. They can be red, green, blue or white in color.
LOW POWER FACTOR BALLAST - Ballast that requires about twice the line current of high power factor ballast.
LUMEN MAINTENANCE - Lumen output provided by a lamp at given point in or percentage of it's life.
LUMENS - a unit of measure used to describe the amount of light that a lamp (light bulb) produces or emits.
MEAN LUMENS - Average light produced when lamp has been operating about 40% of rated life.
MOGUL BASE - used on high-wattage incandescent and HID lamps.
NEMA - National Electrical Manufacturers Association. Includes lamp, electrical device and larger fixture manufacturers. NEMA develops consensus ratings and designations for various products.
NEON LAMP - Low pressure arc discharge lamps that operate at high voltage. Used for decoration and signage purposes.
NORMAL (LOW) POWER-FACTOR BALLAST - Ballast of multiple-supply type that doesn't have means for correcting input power factor.
OPEN RATED LAMP (MEDIUM BASE) - Designed for open fixtures; has narrower neck than standard medium base lamps to fit into an exclusionary medium socket for open fixture use.
OPEN RATED LAMP (MOGUL BASE, EX39) - Has extended contact pin on bottom of base; can only be used with open fixture mogul sockets designed to prevent electrical contact if unshrouded, standard base lamps are used.
OPERATING CURRENT (LINE) - RMS current measured through input terminals of ballast which is operating a reference lamp.
PAR LAMPS - Parabolic Aluminized Reflector Lamp. Constructed of hard glass with a separate back reflector and front legs that are fused together. PAR lamps may be line or low voltage and can be used unprotected outdoors.
PL LAMP - a nickname for a twin tube fluorescent lamp coined by Philips Lighting, a large manufacturer of lamps.
POSITION ORIENTED MOGUL BASE (POMB, EP39, EP40) - Used with horizontal burning lamps; has aligning pin embedded in base for proper lamp orientation.
POTTING - Plastic material used to completely surround and cover components of electromagnetic ballast, protecting them & dampening sound.
PULSE START LAMP - Specially designed metal halide lamp that uses a ballast with ignitor for starting.
QUARTZ LAMP - Or quartz halogen. Term derives from the quartz glass that encloses the filament and halogen gas. Quartz glass can withstand the high pressure of the halogen lamp, but it transmits more UV radiation than ordinary hard glass. Touching the quartz glass with bare hands leaves an oily residue that greatly reduces lamp life.
RAPID START - a fluorescent system that does not require starters and takes 1 to 2 seconds to emit light. The ballast preheats the electrodes within the fluorescent lamp and initiates the arc without a starter or the application of high voltage.
RFI (RADIO FREQUENCY INTERFERENCE) - interference to the radio frequency band cased by other high frequency equipment or devices in the immediate area. Fluorescent lighting systems and AC electronic transformers can generate RFI.
SHROUD - Glass cylinder surrounding arc tube to protect against hot arc tube particles breaking the glass bulb if an arc tube rupture occurs; reduces risk of using metal halide lamps in open fixtures.
STARTING CURRENT (LINE) - RMS current measured through input terminals of ballast 5-15 seconds after lamp is started.
SYSTEM WATTS - Power measured on input terminals of ballast which is operating a reference lamp.
THREE PHASE CURRENT - Current delivered through three wires with each wire serving as return for the other two.
UL (UNDERWRITERS' LABORATORIES, INC.) - Laboratory that sets safety standards for building materials, electrical appliances and other products.
ULTRA VIOLET (UV) - Light that is shorter in wavelength and higher in frequency than visible violet light (literally beyond the violet light).
NO ENTRIES
WARM-UP TIME - Amount of time from ignition of lamp to 90% light output.
WATTS - Measure of energy used or emitted by lamp each second.
XENON - A heavy, colorless, and relatively inert gaseous element that occurs in air as about one part in 20 million by volume and is used especially in thyratrons and specialized flashtubes.
NO ENTRIES
NO ENTRIES
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
