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Glossary of Lighting Terms |
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A American National Standards Institute (ANSI): A consensus organization which coordinates voluntary standards for the physical, electrical and performance characteristics of lamps, ballasts, luminaires and other lighting and electrical equipment. Amps: A measure of electrical current. In incandescent lamps, amps are related to voltage and power as follows: Current (Amps) = Power (Watts) / Voltage (Volts) Apparent Color Temperature: Used to describe the degree of "whiteness" for fluorescent and high intensity discharge lamps. Average Rated Life: The median time it takes for a lamp to burn out. Based upon continuous testing lamps in laboratories, the 1,000 hour rating is the point in time when 50% of the test samples have burned out and 50% are still burning. Average life ratings are based on closely controlled laboratory test of lamps, at their rated voltage, over a long period of production time. Average Rated Life is not necessarily the same as service life; mechanical shock & vibration, voltage fluctuation, temperature and other environmental factors may result in shorter service life. Therefore, as with any average value, some individual lamps may operate longer and some may operate shorter than their Average Rated Life.
B Beam Angle: Indicates the spread of the beam of light. The smaller the number, the tighter and more intense the beam. Same as beam spread measured at 50% of the maximum intensity. This angular dimension of the cone of light from the reflectorized lamps (such as R and PAR types) encompasses the central part of the beam out to the angle where the intensity is 50% of maximum. Beam Spread: A measure of the angular spread of light from reflectorized lamps such as R and PAR types, typically including the central part of the beam within 50% of the maximum .
C Candlepower: A measure of intensity of light in a given direction (see Candela). Center Beam Candlepower: A photometric measurement taken at the beam center of a fully illuminated lamp. This measurement is typically the brightest point, in terms of lumens, of a given beam spread. Coefficient of Utilisation: A percent of initial lamp lumens that reaches the work plane as determined by surface reflectance’s, room shape, and fixture efficiency. Color Rendering: Defines how light from the lamps affects the colors of objects being illuminated CRI: Color Rendering Index (CRI) is a term used to describe the extent to which an artificial light source is able to render the "true" color of objects as seen by natural outdoor. The closer the CRI of a lamp is to 100, the more "true" it renders colors. Color rendering is measured on an index from 0-100, with natural daylight and incandescent lighting both equal to 100. Objects and people viewed under lamps with higher color rendering indexes generally appear more true to life. Color Temperature: Color temperature is a measure of the visual "whiteness" of a source and is expressed in degrees K. (Kelvin). Red/orange/yellow colors and light sources from this side of the spectrum are described as a warm, with a low color temperature (incandescents). Colors and light sources toward the blue end with a high color temperature are referred to as cool (natural daylight). Compact Fluorescent Lamp: The general term applied to families of smaller diameter fluorescent lamps, some of which have built-in ballasts and BC or ES caps for easy replacement of incandescent lamps. Use advanced 'electronic' technology to produce a highly efficient and compact light using a fraction of the electricity of ordinary incandescent bulbs. These bulbs use about one-fifth to a quarter of the electricity of standard bulbs and last up to ten times as long.
D Dimmable: An electrical device that enables you to vary the light output of the lamp.
E Electromagnetic Spectrum: An orderly arrangement of radiant energy by wavelength or frequency. Energy: The electric power input, measured in kilowatt-hours (kwh). Energy saving lightbulb: Uses advanced 'electronic' technology to produce a highly efficient and compact light using a fraction of the electricity of ordinary incandescent bulbs. These bulbs use about one-fifth to a quarter of the electricity of standard bulbs and last up to ten times as long.
F Filament: Very thin coiled wire used in incandescent lamps which is heated by an electric current to produce light.
Fluorescent
Lamp: A lamp in which electric discharge of ultraviolet energy excites
a fluorescing coating (phosphor) and transforms some of that energy to
visible light. This lamp uses less electricity and last for a longer time
than incandescents. Footcandle: A measurement of the quantity of light falling onto a surface or subject. One footcandle is equal to one lumen per square foot. One footcandle equals 10 lux. Frosted: Internal Frosting of the glass of the bulb
G High-Intensity Discharge Lamp (HID): General term for a mercury, metal halide or high-pressure sodium lamp. HIR LAMPS: HIR lamps are a new form of high efficiency tungsten halogen lamp. By coating the filament tube, it reflects the infrared back onto the filament, reducing the power needed to keep the filament hot.
I Incandescent Lamp: A light source which generates light utilizing a thin filament wire (usually of tungsten) heated to white heat by an electric current passing through it. Incandescent lamps are the oldest form of electric lighting technology. Initial Lumens: Light output of a lamp Instant On: A type of fluorescent lamp-ballast circuit designed to start fluorescent lamps as soon as the power is applied.
J Kilowatt Hour (kwh): The measure of electrical usage from which electricity billing is determined. For example, a 100-watt lamp operated for 1000 hours would consume 100 kilowatt hours, (100 watts x 1000 hours = 100 kwh). At a billing rate of $0.10/kwh, this lamp would cost $10.00 (100 kwh x $0.10/kwh) to operate.
L Light: Radiant energy which can be seen or sensed by the human eye. Visible light is measured in lumens or candlepower. Light Center Length: This dimension defines the location of the filament to the lamp base. It is measured from the geometric center of the filament to a specified point of, or plane through, the base. Lumens: A lumen is a measure of the amount of light produced by a lamp. A lamp's light output rating expresses the total amount of light emitted in all directions per unit time. Lumen Maintenance: A measure of how a lamp maintains its light output over time. It is often expressed as percent initial lumens vs. percent rated life. Lumens Per Watt: A measurement of the efficacy of a light source in terms of the light produces by the power consumed. For example a 100 watt lamp producing 1750 lumens give 17.5 lumens per watt. Luminaire: The international term for a complete lighting unit consisting of a lamp (or lamps), together with the parts designed to distribute the light, position and protect lamps and connect them to the power supply. Luminaire Efficiency: The ratio of lumens emitted by a Luminaire to those emitted by the lamp or lamps used. Luminance: Measurable quantity (candelas per square inch or per square meter) which is related to perceived brightness. Lux: The ratio of lumens to surface. Measures the light that actually reaches the target. Lux varies depending upon how far away the target is from the light source and other environmental factors such as wall color, reflectors, etc. This is the SI (International System) unit of illumination. Generally, one lumen uniformly distributed over an area of one square meter.
M
O Phosphor: A coating, deposited on the inner bulb surface of fluorescent lamp types. Phosphors are designed to absorb short wavelength ultraviolet radiation and to transform and emit it as visible light. Power Factor (PF): A measure of how efficiently a device uses power. Power factor may range from 0 to 1, with 1 being the ideal. A device that converts all the power supplied to it by the power utility into watts is said to have a power factor of 1. Devices with PF greater than or equal to 0.90 are referred to as High Power Factor (HPF) devices, whereas devices with PF less than 0.60 are referred to as low power factor devices.. Incandescent lamps always have power factors close to 1.0 because they are simple “resistive” loads. The ballast used determines the power factor of a discharge lamp system. “High” power factor usually means a rating of 0.9 or greater. The power factor of “core and coil” electromagnetic ballasts may be as low as 0.5 – 0.6.
Q
S Soft glow / Opal: A fine white powder coating which produces a more even brightness than pearl where diffusion of the light is important. Spotlight: Beam of light projected onto a particular object or location. Striplight: Tubular shaped incandescent lightbulb used in bathroom shaver lights, picture lights and under-cupboard lighting. (See also Fluorescent Lamps)
T
U Underwriters Laboratories (UL): A private organization which tests and lists electrical (and other) equipment for electrical and fire safety according to recognized UL and other standards. A UL listing is not an indication of overall performance. Lamps are not UL listed except for compact fluorescent lamp assemblies – those with screw bases and built-in ballasts.
V Voltage: A measurement of the electromotive force in an electrical circuit or device expressed in volts. The voltage of a circuit is the electrical pressure it provides. In an incandescent lamp, voltage designates the supply voltage to which the lamp should be connected, and is related to current and power as follows: Voltage (Volts) = Power (Watts) / Current (Amps).
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