Glossary:

A list of definitions to some common phrases, acronyms, and initials in the lighting and ceiling fan industy.

A

A lamps	General service lamp, most common incandescent lamp with a medium base also known as Edison base.
Accent Lighting	Directional and localized lighting that will highlight, dramatize, and focus attention on a defined space. This lighting function is mainly used with recessed downlights, Track Lighting, and specialty lighting.
Acid Finish	Chemically distressed or weathered finish.
Aged Finish	An oxidized finish, usually found on brass and copper, that creates a weathered appearance. Also known as rust.
ALA	American Lighting Association is a company that provides lighting education to help users understand the fundamentals of lighting and lighting design.
Alzak	A trade name for a method of anodizing, now a generic term for brightened, anodized aluminum. This finish has a brushed nickel appearance.
Ambient Lighting	Lighting that provides background brightness, so you can move around a space. Reduces contrast between sources of local brightness. A form of general lighting with low glare.
Anodized	A finish consisting of a thin, near transparent coating of aluminum oxide on the surface of an aluminum reflector. It is highly durable.
Antique Finish	A finish that simulates aging, often accompanied with a dark pigment paint wiped across a metal part.
Aperture	Aperture refers to the finished size of the opening in a recessed downlight.
Arc discharge	Light created when gases are excited by an electrical current. Fluorescent lamps and HID lamps use this principle.
Architectural Lighting	Generally refers to built in lighting such as recessed downlights, coves, calences, and low-voltage track systems that are designed to match existing architecture. May also mean architecturally styled fixtues, such as track systems.
Atmosphere	The emotional feel of a space. Created by using multiple lighting layers.

B

BR Lamp	Bulged reflector lamp. Modified R lamp to meet EPACT standards. Produces a soft-edged beam that is less precise and narrower than PAR lamps. These are most commonly incandescent lamps.
Back Light	Light from behind an object. Makes a silhouette, creating a dramatic outline.
Baffle	Part of the fixture that blocks light to prevent glare and control brightness. Often painted black to absorb excess light.
Ballast	Component required for fluorescent lamps and HID lamps. Provides enough voltage to start the lamp, then limit current for continuing operation.
Ballast Factor	Percentage of rated light output by a ballast. Typically 87%.
Beam	Main part of a directional light, accent light, or downlight.
Beamspread	Width of the beam in degrees. Defined as the point where intensity falls to 50% of maximum candlepower. For most PAR and MR lamps, this is the apex angle. For asymmetrical beams, this is expressed as length x width. Most reflector haloge light bulbs come in varing degrees.
Beveled Glass	Clear glass, often with high lead content, with edges cut to add depth and glitter.
Blade Span	The blade span equals the overall diameter of a ceiling fan’s blades or the distance from blade tip to blade tip while the ceiling fan is in motion.
Bullet	An accent light with a round back used to create dramatic light to a small space.
Bulb	An incandescent lamp glass. Also refers to the outer glass envelope of the lamp.

C

Candela	A unit of candlepower.
Candlepower	Intensity of light in a particular direction. Center beam candlepower is the intensity in the middle of the beam.
Canopy	Fixture part that covers an outlet box or attachment point. Also known as the decorative piece used to cover the electrical wires and mounting hardware on a ceiling fan.
Cans	Another term for recessed downlight housing.
Capacitor	Electric device that is used to control power. First invented by Emerson Fan Company to control fan speeds.
Casablanca Fan Company	The Casablanca Fan Company is a manufacturer of high-end ceiling fans. They are located in Pamona, California.
Ceiling Fan	Ceiling fans are used to create a cooling effect produced by air circulation and to conserve energy by distributing cold and hot air when air conditioning.
CFL	Compact Fluorescent Lamp. CFL's are light bulbs that provide bright, warm light but use up to 75% less energy than most incandescent lamps, produce 75% less heat, and CFL's last up to 10,000 hours or about 7 years. CFL's are now available in different shapes and sizes to fit in almost all light fixture sockets.
Chain Pliers	Tool with jaws used to pry open links of chain.
Circuit	Wiring path for electricity.
Circuit Breaker	Protecting device that breaks the electrical path if overloaded. Located in the electrical panel.
Color Rendition	How light changes perception of color.
Color Rendering Index	A measure of how light sources render colors. The higher, the better color rendering, given the color temperature. Use Fluorescent lamps of at least 80 CRI for most residential applications.
Color Temperature	The appearance of white light, in terms of warmth or coolness. Shown in degrees Kelvin. Warm color corresponds to lower color temperatures. Color Temperature is mainly used in fluorescent lamp selection.
Compact Downlight	Small recessed incandescent fixtures generally 5 inches deep, an aperture of 4 inches or less.
Compact Fluorescent	Small, single ended CFL. Available in many configurations. Good color rendering, but requires a ballast that is not included with the lamp. This lamp uses up to 75% less energy than most incandescent lamps, produces 75% less heat, and lasts up to 10,000 hours or about 7 years.
Cone	Reflector used in the aperture of a downlight. Also, nerve endings in the focal area of the retina of the eye, sensitive to color.
Contrast	Relative brightness of an object against the immediate background.
Cool	White light with a bluish tint. Fluorescent lamps with 3500K or higher temperature, works well in industrial or commercial areas.
Cove Lighting	Light built into the cove (ledge of shelf at the upper part of a wall) that illuminates the ceiling.
Crystal	Fine quality transparent glass available in different quality levels. Swarovski Crystal is the leading high end crystal manufacturer.
Current	Flow of electrons through a wire, measured in amperes.
Cutoff	Measure of glass control: the angle at which you can no longer see the lamp or it's image in a fixture. Measured directly below the fixture.

D

Damp Location	UL listing for a fixture used in a moist but unexposed area, such as a bathroom or under an eave.
Dark Skies	Refers to the International Dark Sky Association, which campaigns against light pollution. A "Dark Sky Fixture" emits no light above horizontal.
Daylight	Light from the sun. Includes direct sunlight, sunlight scatterd by the atmosphere, and sunlight reflected from clouds or other surfaces. Each type has different properties.
Dead End	End of a piece of track now receiving electic power. May also refer to the cap at a dead end.
Decorative Lamp	Incandescent bulb in a decorative shape such as a flame, globe, cromatic or chimney.
Depreciation	Loss of light output as a lamp ages. Loss of light from dirt build up is dirt depreciation.
Dichroic Coating	Film that reflects visible light and transmits infrared light. Lamps with this provide a cooler beam because most heat goes out the back.
Diffuser	Light control device that spreads light by scattering it.
Dimmer	Control that varies the output of the light source by reducing the voltage or current to the lamp. Light dimmers are a great way to start conserving energy.
Dimming Ballast	Electronic ballast for dimming Fluorescent lamps; requires appropriate fluorescent dimming control.
DIP Switch	Miniature rocker-style switch that mounts to the circuit boards of electronic controls. DIP switches program digital controls usually on remote transmitter and receiver devises.
Direct Current	Continuous flow of electricity, as from a battery.
Direct Glare	Intense glare from a bright source of light.
Direct Lighting	Lighting that casts at least 90% of the light downward.
Direct-Indirect	Lighting that casts approximately half the light downward and half upward.
Directional Lighting	Lighting that strikes an object or surface predominantly from a single direction.
Distribution	Luminous distrubution of a lamp or fixture.
Downlight	Fixture that directs all light down. Often refers to a recessed fixture.

E

Efficiency	Total lumen (light) output from the fixture divided by the total lumens emitted from the lamps used in the fixture. Shown as a percentage.
Electronic Ballast	Supplies power to Fluorescent lamps at very high frequency. Uses less power than magnetic ballasts, and reduces hum and lamp flicker.
Electronic Dimmer	Uses a solid state switch (Triac) to turn off the current at very high frequency and so reduce lamp output.
Electronic Switch	Solid state relay in a wall box that accepts control signals, provides on/off control as part of a multi-scene or central control system.
Electronic Transformer	Steps line voltage down to the lamp voltage using electronic switching rather than magnetic windings. Smaller and lighter than magnetic ones, but usually needs a special dimmer.
Emerson Fan Company	A ceiling fan manufacture best known for the K55 fly wheel motor and inventing the fan capacitor. The sister company of Emerson Motors a 20 billion dollar company.
Enclosed Downlight	Recessed fixtures enclosed at the bottom by a lens or diffuser. Produces a medium beam and most often UL damp or Wet Listed, and used mainly in kitchen, patio and bath areas.
Energy	Light is a form of radiant energy. Electric light also relies on man-made energy in the form of electricity, the major cost of light. Energy is power consumed over time. Energy is measured in watt-hours.
Energy Saving Ballast	A magnetic ballast with relatively low power losses. Electronic ballasts are preferred and generally in use today.
Energy Star Rated	A program of the US Dept. of Energy and EPA. Qualifies lighting equipment and other appliances in terms of energy efficiency and other quality and performance parameters. Lighting fixtures must offer the same or more light while using two thirds less energy than incandescent fixtures. They must last at least 10,000 hours or about 7 years without changing the light bulb. They must make bulb replacements that plug in rather than that screw in so that people cannot put incandescent bulbs back in the fixture. Energy Star Rated Light Fixtures and Ceiling Fans..
EPACT	Federal Energy Policy ACT of 1992. Regulates lamp efficacy, requires lamp labeling, requires states to adopt energy codes, and calls for luminaire efficacy ratings (LER).
Extended Life Lamp	Incandescent lamp with over 2500 hours of rated average life and reduced output, uses stronger filament.
Eyeball	Recessed adjustable accent light. The spherical lamp holder pivots at the ceiling line for 25-40 degree adjustment, but also protrudes below the ceiling. The eyeball trim is slowly fading out of style but is still used by electrical contractors that are not familiar with the latest lighting trends.

F

Facet	Side of a prism usually referring to a crystal.
Filament	Tightly colied tungsten wire of an incandescent lamp, glows to produce light when electricity flows through it.
Fill Gas	With incandescent lamps, usually krypton or argon with nitrogen. With Fluorescent lamps, usually argon and some krypton. With halogen incandescent lamps, halogen.
Filter	Accessory that changes the spectral quality of light by absorbing or redirecting unwanted wavelengths. Color filters absorb all colors except the desired color.
Filtering	Also called chokes or debuzzing coils, smoothes the electrical current to reduce noise and interference. Most magnetic transformers use debuzzing coils to reduce line noise when dimming.
Fitter	Part of a fixture that accepts a glass or plastic globe. The diameter of the fitter determines the size of the neck or opening in the globe.
Flood	The wide distribution of a reflectorized lamp. Also a fixture with a widespread light beam. Abbreviated FL.
Fluorescent Lamps	Operates by creating an electric arc inside a gas-filled tube. The arc excites the gas, producing ultra-violet energy, which causes the phosphor coating in the lamp to flow. The phosphors determine the color of the light. Needs ballasts to be used properly.
Fluorescent Troffers	Commercially used recessed fixtures for 2 foot and 4 foot linear Fluorescent lamps.
Footcandle	Abbreviated FC, unit of illuminance (light falling on a surface or object). One lumen falling on one square foot is one FC.
Four-Way Switch	Used with 2 three-way switches to allow a fixture to be used from three or more locations.
Frame-In Kit	Plate or housing for a recessed downlight that installs in the ceiling and connects to the circuit.
Framing Projector	Fixture with shutters and a lens, creating a sharp-edged beam to outline pictures and other objects.
Full Function Remote	Dimming control that wires to a digital dimmer and enables you both to adjust intensity and switch on/off from multiple locations. Ceiling Fans also use remotes to control fan speeds and light dimming.
Fuse	Replacable safety device that provides circuit overload protection. When it overheats, a wire breaks (blows) to open the circuit.

G

G Lamp	Globe-shaped incandescent lamp
Ganging	Mounting wall box dimmers or other devices in the same enclosure and faceplate. High wattage dimmers must be derated when the are ganged together to reduce the size of the heatsink.
General Lighting	Ambient lighting for basic tasks in the room.
General Diffuse Lighting	Lighting distributed equally in all directions, minimizes form, texture, and shadows.
General Service Lamp	A lamp or medium based A19 lamp.
Gimbal Ring	An adjustable ring that holds the PAR or MR lamp by the rim. Such a track fixture has no housing.
Grazing Light	Directional light at an acute angle, which emphasizes texture. The source must be close to the surface.
Greenhouse Gasses	Gasses (particularly carbon dioxide) that collect in the lower atmosphere, they trap heat and contribute to global warming. Created by burning fossil fuels to generate electricity. How CFL's Reduce Greenhouse Gases
Grounding	Connecting electrical components to the earth for safety from lightning and electrical shock.

H

Halogen Lamp	Incandescent lamp with halogen gas fill, and a quartz glass capsule (requiring a separate glass shield or enclosure). Due to the Halogen Cycle, they operate at higher temperatures, producing more lumens per watt and brighter light than ordinary incandescent. Lamp life is extended and lumen maintenance is improved. Lamp types include A, MB, T, PAR, and MR.
Hand Blown Glass	(Really mouth blown) individually produced glass made by artisans who blow molten glass to different shapes. Original techniques of blown glass came from the island of Murano, Italy in the 1300s.
Heat Sink	Conducts head away from sensitive components to maintain cool operation.
Hertz (Hz)	Unit of frequency, denoting cycles per second. Household current (in the US) alternates at a frequence of 60 Hz.
HID Lamp	High Intensity Discharge lamp, includes Metal Halide, Sodium, and Mercury.
Hot Beam	The central, high intensity beam of a spot lamp.
Hot Spot	A small area of higher illumination that the surrounding surface, typically produced by placing a light source too close to the surface. This is also common with cheaper made glass. Higher end glass products do not have hot spots.

I

Illuminance	Light falling on an object or surface. Typically measured in footcandles. Lux is the metric unit.
Incandescence	Light produced by heating a material so it glows.
Incandescent Lamp	Produces light with a wire filament, which incandesces to create light as it it heated.
Indirect Lighting	Lighting that directs all or most light upward for ambient or general illumination. Few shadows, but diminishes form and texture.
Inductive Load	Magnetic transformer or motor.
Induction Lamp	A discharge source that uses a high-frequency current to induce an arc, rather than strike one with electrodes. Quality is like a CFL. Expensive, but long lamp life.
Instant Start Ballast	A ballast that starts the lamp by means of high voltage, without pre-heating the cathodes. Electronic ones are more efficient but sacrifice lamp life when frequently switched on and off.
Instant Start Lamp	Fluorescent lamp designed to start almost immediately at full brightness. No starter is used.
International Dark Sky Association (IDA)	The IDA is an organisation whos mission is to preserve and protect the night time enviromentand our heritage of dark skies through quality outdoor lighting.
IR Lamp	Infrared-Reflecting Halogen Lamp. A special interior coating redirects infrared energy onto the filament, which increases output without added power. Infrared coated lamps are about 33% more efficient that conventional halogen types.
Insulated Ceiling Fixture (IC Rated)	Recessed downlights suitable for direct burial in thermal insulation.
Integral Ballast	Allows a screw-base CFL to operate in an incandescent fixture.
Integral Transformer	A transformer housed within a low voltage fixture.
Intensity	Luminous intensity, or candlepower, is the strength of the light in a particular direction, measured in candelas.

J

Jack	Plug-in stem for low-voltage fixtures.
Junction Box	Box that protects wires and supports fixtures, also known as an outlet box, 1900 box or fan box.

K

Kelvin	Unit of temperature used in color temperature measurment.
KWH	Kilowatt-hour, a measure of electrical energy used. 1 KWH = 1000 watts used for 1 hour, or 1 watt used for 1000 hours..

L

Lamination	To fuse thin sheets of material together.
Lamp	A manufactured light source. Includes base, bulb, and internal light-producing structure (arc tube or filament).
Lamp Holder	Socket that holds a lamp in place and provides an electrical connection. Also refers to a plain track fixture, typically with a stationary socket.
Lamping	Equipping a fixture with a lamp.
Lead Crystal	Fine quality glass with a high content to lead oxide.
Leaded Glass	Small pieces of glass joined at the edges with metal, also called bound glass.
LED	Light Emitting Diode. A small solid state device that emits light by running small amounts of current through semiconductors. Suffers from high cost and color issues, but still used in non-residential areas.
Lens	Transparent device used to control light beams, refracts rays to light to change the direct of the beam. A convex lens bends light inward and bulges out; a concave lens bends light outwards.
Light Box	Demonstrates the color rendering properties of different lamps. You can view light from various lamps without direct view of the source.
Light Distribution	Pattern of light created in a room, or made by a fixture.
Light Guide	Component that conducts light from source to end, sometimes pipe or fiber.
Light Pollution	When man-made lighting diminishes the natural environment. Effects include energy waste and reduced nighttime visibility. IDA has new light fixture regulations for reduced light pollution.
Light Trespass	When light falls on neighboring property.
Lighting	Lighting is natural illumination of objects from sun light and illumination from artificial light sources such as chandeliers, lamps and light fixtures.
Live-End Feed	Another name for Power Feed.
Local Transformer	Transformer associated with a single nearby fixture. Not integrated into the fixture housing.
Louver	An array of baffles or reflectors that block light at certain angles and control glare.
Low Ceiling Adapter	A device used on ceiling fans to lower the overall distance from the ceiling to the bottom of the fan. This adapter replaces the downrod and secures the top of the motor housing to the canopy on the ceiling. The low ceiling adapter usually reduces the overall height by 3 inches.
Low-Temperature Ballast	Starts Fluorescent lamps at lower temperatures. Also known as cold weather ballasts or zero degree ballasts
Low Voltage Fixtures	Recessed, task, decorative, track, or landscape fixtures for low voltage lamps.
Low Voltage Housing	Recessed housing with an integral or remote transformer.
Low Voltage Lamps	Incandescent lamps that operate at 6, 12, or 24 volts. Needs a step-down transformer to reduce the voltage from the normal household 120V.
Low Voltage Track	Track powered at low voltage by a step-down transformer. Particularly compact, as the elements don't have transformers.
Low Voltage Trim	Either the dedicated trim to a low voltage housing, or a reflector trim with an integral transformer, installed in a standard housing.
Lumen	Luminous flux, a unit of light output
Lumen Depreciation	The reduction in light output as the lamp ages. Low with halogen, moderate for fluorescent, high for most HID sources.
Lumens Per Watt (LPW)	Light output per unit of energy consumption, shows efficacy.
Luminaire	A complete lighting unit, consisting of lamp and fixture, including ballast.
Luminance	Light reflected or emitted from an object, commonly called brightness. Technically, a measurable quantity; brightness refers to how to surface appears to the eye. Luminance Ratio is the relative luminance or two objects or surfaces.
Luminous Ceiling	A continuous plane of diffusion, translucent ceiling panels with fluorescent strip lights above. Often seen in kitchens.
Lux	Metric unit of illuminance, equal to one lumen per square meter. 1 lux = 10.76 footcandles.

M

Machine-Blown Glass	Shaped by mechanically forcing air into molten glass so that it takes the shape of a mold. Incandescent lamps are machine-blown.
Magnetic Ballast	Uses copper windings and a magnetic core to regulate the current that drives a lamp. Cheap, but produce a hum, flicker, and are less efficient and heavier than electronic ballasts.
Magnetic Transformer	Uses copper windings and a magnetic core to reduce line voltage to low voltage. Simpler and cheaper to dim, but are heavier and bulkier than electronic transformers, and produce a hum.
Mercury	An element used in a fluorescent lamp. When vaporized, emits UV radiation that excites the phosphors. A toxic substance, but harmless when contained in an unbroken lamp.
Mercury Lamp	An HID lamp, largely obsolete.
Metal Halide Lamp	A popular HID lamp with a cool, white color. Ceramic Metal Halide Lamps enjoy high CRI, are available in a warm color, and are increasingly common in some areas.
Motion Detector	Also known as occupancy sensor.
Mounting Height	Distance between task plane and fixture.
MR Lamp	Multi-faceted Reflector Lamp, MR16 is the most popular. Surrounds a halogen capsule with a glass or metal reflector with many surfaces or facets. Needs a glass cover, either integral or with the fixture. Most incorporate dichroic reflectors that pass heat out the back and reflect a cooler beam.
Multi-Scene Control	Dimming system that creates different settings/scenes for the lights in a room, generally with a push-button keypad.

N

Nanometer	One billionth of a meter, the wavelengths of light range from 380-780 nanometers.
National Electrical Code	Set of standards for wiring practice and the electrical devices used to implement them. NEC is a private enterprise.
NEMA	National Electrical Manufacturers Association, which includes the electrical device, lamp, and larger fixture manufacturers. NEMA develops consensus ratings and various products, mostly industrial and commercial.
Neodymium Lamp	Incandescent lamp with neodymium coating on the inside of the bulb. Yellow light is absorbed, making the light seem whiter.
Neon Lamp	Low pressure arc discharge lamps that operate at high voltage, similar to cold cathode.
Neutral Conductor	Part of the circuit that carries the current back and completes the circuit.
Non-Dim	A dimming zone or channel set for on/off control only.

O

Occupancy Sensor	Control that uses ultrasonic or passive infrared detection to sense whether someone is present or not, and to turn on or off appropriately. "Automatic On" will turn on when someone is present. "Manual On" requires a switch. Both turn off when nobody is sensed.
Opal Glass	Milky, translucent glass produced by adding ingredients to clear glass; used for diffusing light.
Outlet Box	Also called junction box.
Over-Voltage	Incandescent lamps experience reduced lamp life when used above rated voltage.

P

PAR Lamp	Parabolic Aluminized Reflector Lamp. Generally constructed of hard glass, with a separate back reflector and front lens that are fused together. May be line or low voltage and can be used unprotected outdoors. Their beam pattern has an uneven field.
Parabolic Louver	Grid of parabolic-shaped reflector blades that provide a highly efficient light shield in a recessed fluorescent troffer. Made of either molded aluminized plastic or aluminum.
Parabolic Troffer	Recessed fluorescent fixture with a parabolic louver.
Parabolic Reflector	Reflector with parabolic contour, which reflects light emanating from the reflector's focal point into a beam of parallel rays. Used in PAR lamps.
Passive Infrared Sensor	Detectors that senses small movements in your thermal image, not fooled by wind but requires clear line of sight.
Pendant	Fixture suspended from the ceiling on cable, chain or stem. May also refer to the stem itself.
Phosphors	Mineral coating on the inside of a fluorescent tube, determines the color temperator and rendering of the lamp.
Photocell	Light-sensitive devices used to operate fixtures according to available daylight. Usually used to turn on lights at dark and turn them off at dawn.
Photometry	Light measurement that rates lamps and calculates the luminous distribution of fixtures and reflectorized lamps.
Pinhole	Used for inconspicuous accent lights, a recessed downlight including a faceplate with a small aperture.
Plenum	The space between the ceiling and the floor - or roof - above.
Polycarbonate	Heat and shatter resistant plastic, usable indoors and outdoors. Can be transparent, translucent, or opaque.
Power Factor	Relationship between power consumption (watts) and current draw (amps) in a device. The maximum is 1.0. Low power factor devices require larger wires and additional circuiting.
Power Feed	Connection point for power in lighting systems. It may be at the end, an intersection, or floating.
Preheat Lamp	A fluorescent lamp that uses a starting switch to pre-heat the electrodes in to start the lamp. Most small CFL's are preheat types.
Preset	Setting for a dimmer that can be selected without readjusting dimmer intensity each time. Usually activated by a rocker or pushbutton.
Prism	Refractor of transparent glass or plastic, with three or more straight sides. Light entering one side of the prism bends and exits another side.
Prismatic Lens	A light shielding that consists of many tiny prisms, which redirect the light rays so as to control brightness.
PS Lamp	Pear-shaped incandescent lamps of high wattage.

Q

Quartz Lamp

Term for a Halogen Lamp, also Quartz-Halogen. Comes from the quartz glass capsule that encloses the filament and halogen gas. Transmits more UV radiation that ordinary hard glass. Touching it with bare hands leaves an oily residue that reduces lamp life.

R

R Lamp	Reflector Lamp. Soft-glass reflectorized lamp with a generally smooth distribution.
Rapid Start	The most common type of linear fluorescent lamp. Rapid start ballasts preheat the lamp electrodes; the lamp is fully bright within 3 seconds. No separate starter is required. Magnetic ballasts use rapid start circuits. Electronic ballasts can be rapid start, instant start, or programmed start. An instant start ballast on a rapid start lamp saves energy but reduces lamp life. Fluorescent dimming ballasts are rapid start.
Rare-Earth Phosphors	Mineral coating with rare-earth elements used in Fluorescent lamps. Produce good color rendering with high light output and reduces lumen depreciation. RE830 designates such a lamp, CRI from 80-89, and color temperature of 3000K.
Receptacle	Also known as Duplex Outlet.
Recessed Downlight	Fixture mounted above the ceiling. With downlights, only the aperture and trim visible from below. With fluorescent troffers and luminous ceilings, only the lightshield is visible. Provides direct downlighting.
Reflectance	Percent of light reflected from a surface.
Reflected Glare	Glare from the Specular Reflection of bright light sources. You often experience this when reading a glossy magazine, working on a polished surface, or looking a computer screen.
Reflection	Light bouncing off a surface. It is not absorbed or transmitted.
Reflector	Part of a fixture that redirects light to control brightness, beamspead, or intensity. Frequently specular, but may also be diffuse, matte, or glossy.
Reflector Lamp	Also known as R lamp.
Reflector Trim	Finishing Section or Trim for a recessed downlight, which uses a reflector.
Reflectorized Lamp	Incandescent lamp with a reflector integrated into the envelope. They produce directional beams.
Refraction	Bending light as it passes through a lens or prism to change the direction of the beam.
Relay	Switches that controls a high-power load with a low-power signal.
Remodeler	Rough-In section for a recessed downlight that is designed to install from below into a finished ceiling.
Remote	Electronic control mounted separately from the master or individual dimmer, permitting operating from multiple locations.
Remote Transformer	Separately mounted transformer that powers a low voltage fixture or system (landscape or indoors).
Rods	Nerve endings in the "non-focal" area of the retina of the eye. Sensitive, but only see black and white.
Rough-In	Process of wiring a home and installing the rough-in sections of fixtures and the back boxes of electrical devices, done before the finishing work.
Rough-In Section	UL term for the aprt of a recessed downlight that mounts to the building and connects to the electrical circuit. A finishing section attaches to the rouch in, providing optics and trims out the ceiling. Also known as cans, frame-in kits, rough-ins, rough-in kits, and housings.
Rust	Corrosion of metal from exposure to moist air and other elements, also known as oxidation. As a finish, it is a reddish-brown color produced by a chemical process or paint.

S

Sand Casting	A costly process where molten metal is poured into a mold of compacted sand. These molds can only be used once.
Satin Finish	Slightly textured or brushed surface, with a fine grain, that reflects light with some diffusion.
Scallops	The arched or scallop shaped pattern of light created when you locate a directional source close to a wall.
Scene	Specific setting for a group of channels, zones, or dimmers. A multi scene control lets you select the different settings by pushing a button.
Sconce	Wall bracket derived from the form of a candelabra, often with exposed or decorative light sources.
Semi-Direct Lighting	Distribution of light that is mostly down.
Silhouetting	Lighting technique that creates a dramatic outline by back lighting, used in landscape lighting.
Single-Pole Switch	Operates a fixture or group of fixtures from one location.
Sloped Ceiling Adapter	A device used on ceiling fans to enable the fan to hang at a greater degree of slope than what comes standard. Traditionally ceiling fans come with a ball joint mounting system allowing them to hang up to 29 degrees. A sloped ceiling adapter replaces the original ball joint allowing the fan to hang from 29 degrees to 52 degrees. Different fan manufacturers sloped ceiling adapters are rated at varying degrees.
Soffit	The underside of an overhead component, such as an arch, beam, balcony, or cornice.
Soft-Edged Beam	Light pattern where the intensity diffuses gently out from the center. Characteristic of R lamp downlights, A lamp downlights, accent lights, and fixtures with spread lenses.
Soft-White Lamp	Incancescent lamp with a dense, milky-white silica coating on the inside of the bulb; conceals the filament and diffuses the light.
Solid Brass	Fixture or parts made entirely of brass. Not plated or simulated. Solid brass parts are "solid brass", if not "solid parts", they may be hollow.
Solid State	Electronics that use semi-conductor chips and circuitry, not vacuum tubes.
Solid State Lighting	Also known as LED.
Solid Wood	Fixture or parts made entirely of genuine wood, not veneered.
Specification-Grade	Fixtures with performance and construction suitable for better commercial, institutional, and premium residential uses. More costly and larger, but higher wattage lamps.
Specular Finish	Highly polished and mirror-like. Semi-specular finish is generally bright, but without a well defined mirror image.
Specular Reflection	Light bouncing off a surface so the angle of incidence equals the angle of reflection, which creates a perfect mirror image.
Specular Reflector	Component of a highly polished metal, usually aluminum. Used in recessed downlights to make the most comfortable apertures and efficent fixtures with the least glare.
Spinning	Shaping a disk of metal by rotating it on a lathe and pushing it with a forming tool. Also, a part made this way.
Stamping	Forming sheet metal by hitting it with a die. Inexpensive.
Stem Mounting	Suspension by a rod or rigid tube known as a stem.
Strain Relief	Knot or crimp in wire or cord that prevents splices from pulling apart.
Swag	Chain draped across the ceiling. Such a pendant won't hang directly below the canopy.
Switch Leg	Wiring that connects the dimmer output or switch to the fixture or load being controlled.

T

T Lamp	Also known as Tubular Lamp.
Task Lighting	Localized light for specific visual applications.
Textural Rendition	How poorly or well a light source shows surface texture, such as stone, stucco, or brick.
Thermal Protector	Device that shuts off when fixture overheats or is improperly buried in insulation. Recessed incandescent fixtures and fluorescent ballasts must be protected.
Three-Way Lamp	Incandescent lamp with two filaments that can provide three levels of lights when switched in sequence.
Three-Way Switch	Operates a fixture from two locations. Also known as a three-pole switch, as it it connected to three wires.
Three-Way Dimmer	Dimmer that works with a three-way switch for control from two locations.
Timer	Device that turns lights off and on at programmed times.
Toggle	Lever used for control.
Torchiere	Indirect floor lamp that sends most or all light upward.
Track Lighting	System of electrified channel, or track, and movable lighting elements. A flexible approach to accent lighting. Track lighting is available in line or low-voltage.
Transformer	A device used to lower or raise voltage. Input voltage is on the primary tap, output voltage is on the secondary tap.
Trim	Sometimes the finishing section of a recessed fixture, sometimes the edge or visible part of a recessed downlight.
Trim Ring	Metal or plastic ring on a recessed downlight that covered the cut edge of the ceiling hole.
Tungsten	Ductile metal used to make the wire filament of incandescent lamps.
Tungsten Halogen	See the Halogen entry.
Twin-Tube Lamp	Single-ended CFL with the tube bent into a very tight "U" shape.

U

U Lamp	Linear, double-ended fluorescent lamp, typically T8 or T12, bent into a "U" shape.
UL	Underwriters' Laboratories. A not-for-profit organization that works with the NEC to develop standards for electrical devices, lighting fixtures, and wiring. They also test items for compliance.
Ultrasonic Sensor	Detects motion or occupancy with sound waves. They can detect motion over partial-height partitions, but can be fooled by small animals or rustling curtains.
Ultraviolet Light	Light beyond the visible spectrum, having wavelengths from 10-380 nanometers.
Universal	Name for a plain track light that accepts a wide range of line voltage reflectorized lamps.

V

Valance Lighting	Fixture installed behind a longitudinal shielding member mounted over a window or along a wall; light is distributed down and up.
Vanity Lights	Also known as a bath bracket.
Veneer	Thin sheet of material laminated to a core of stronger and less valuable material.
Volt	Unit of electrical force or pressure.
Voltage Drop	Difference in voltage along a circuit. Voltage drop becomes a problem with low voltage wiring and small cable, reducing the intensity of lights.

W

Wall Bracket	Fixture designed to be mounted on a vertical surface.
Wall Lighting	Lighting directed on a wall to other vertical surface to emphasize that plane, bounce light, or enchance surface texture.
Wall Washing	Lighting a wall smoothly to reduce texture or specular reflection.
Wall Washer	Fixture with special optics that direct light to the top of the wall and de-scallop the distrubution on the wall.
Warm	Light that is tinted red, such as flame.
Watt	Unit of electrical power.
Wave Length	Describes wave phonomena, like energy. Each color of light can be described by its wavelength.
Weathered	Distressed finish to simulate aging.
White Light	Combination of all colors of the spectrum, the light produces by common electric lamps.
Wrought Iron	Soft iron hammered and bent into shape.

Z

Zone	In dimming, lights that are operated together. Also known as channel.