Glossary
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- A-Lamp
The typical bulb-shared lamp with a screw base. The standard general service lamp; the most common incandescent household lamp.
- Accent Lighting
Localized and directional lighting used to highlight, focus attention and dramatize. Accent lighting fixtures include track, recessed, and specialty products.
- Acrylic
A translucent or transparent plastic, suitable for indoor or outdoor use. May be clear, opal, or colored. Does not yellow, but it is not shatter-resistant.
- Aged Finish
An oxidized finish, most often found on brass, to create a weathered appearance. Also called rust.
- Aiming Angle
How you point or direct an adjustable accent light. The aiming angle is calculated from vertical, or nadir. An aiming angle of 30 degrees is effective for paintings and drawings.
- Alloy
A mixture of two or more different metals.
- Alternating Current
Also known as AC. A current that reverses, or alternates, direction. Households use AC that alternates at 60 cycle per second.
- Alzak
Method of anodizing, a term for brightened, anodized aluminum.
- Ambient Lighting
Lighting that provides background brightness, so you can move around a space and that reduces the contrast between sources of local brightness.
- Ampere
Also known as Amp. Unit of electrical current. The rate of electricity flow and circuit capacity are stated in amperes.
- ANSI Designations
Designations for lamps established by the American National Standards Institute. ANSI also develops consensus standards for lamps, ballasts, and test procedures.
- Aperture
The opening of a fixture through which light exits.
- Arch Window
A window with a round portion and a flat portion. These shades are often referred to as “half-moons”.
- Architectural Lighting
A general reference to built-in lighting, such as recessed downlights, cove, and valences.
- Astronomical Clock
A clock programmed according to sunrise and sunset (seasonal) rather than 24-hour time. Used for timing controls.
- Average Rated Life
The number of hours required for half of a large group of lamps to fail or burn out. The actual life of any lamp or small group of lamps is typically different from the average rated life.
- Back Box
Fixture or electrical enclosure installed during the Rough-In phase of the project.
- Baffle
Part of the fixture that blocks light to prevent glare and control brightness. Often painted black to absorb light.
- Ballast
Electrical or electronic component required for fluorescent and HID lamps. They provide enough voltage to start the lamp and limit the current for continuing operation.
- Bath Bracket
The fixture used at a mirror or over a vanity. Ideally a long, well-diffused light source.
- Bay Window
A window extending outward from a main wall; it forms a protrusion from the exterior wall.
- Beam
The main part of the light distribution of a directional light source, accent light, or downlight.
- Beam Spread
The width of the beam in degrees. Beam spread is defined as the point where intensity falls to 50% of maximum candlepower.
- Bi-Pin Base
A lamp base with two pins. Used for some halogen lamps, most MR lamps, and fluorescent lamps.
- Bollard
Architectural outdoor fixture mounted low to the ground on a post for general or path lighting.
- Bracket and Mounting Hardware
Hardware that holds the shade within the window’s frame.
- Branch Circuit
Electrical circuit running from an electrical breaker panel.
- Brushed Finish
Satin, or lightly textured, finish produced by brushing with a wire wheel or buffering with a fine abrasive.
- Bulged Reflector Lamps
Also known as BR Lamps. Modified R lamp (see R Lamp) to meet the efficiency standards of EPACT. Produce a soft-edged beam that is less precise and narrower than those of PAR Lamps.
- Bullet
An accent light with a round back.
- BX Cable
Cable consisting of a flexible metal jacket surround two or more insulated wires.
- Caliper
Commercially available lighting performance evaluation report. A program of the US Department of Energy that tests LED products to assess how well measured performance compares to marketing claims and conventional alternatives.
- Candlepower
The intensity of light in a specific direction. Center beam candlepower is the intensity in the middle of the beam, generally the maximum intensity in a reflectorized lamp.
- Canopy
Fixture part that covers an outlet box or attachment point.
- Central Control
System for controlling all light from one or more locations. Also known as Home Control or Lighting Control/Automation.
- Channel
In dimming controls, a group of fixtures that are operated together. Also known as Zones.
- Circuit
Wiring path for electricity, including conductors, load, and circuit protection.
- Circuit Breaker
A protective device that automatically breaks the electrical path when overloaded. Located in the Electrical Panel.
- Color Rendering Index
Also known as CRI. A measure of how light sources render colors. The reference, CRI of 100, is a full spectrum source of the same color temperature as the lamp. The higher the CRI, the better the color rendering, given the color temperature of the lamp. Use at least 80 CRI for residential applications.
- Color Temperature
The appearance of white light, in terms of warmth or coolness. Color Temperature is measured using a Black Body and is shown in degrees Kelvin. Warm colors correspond to lower color temperatures and cool colors to warm color temperatures.
- Cone
Reflector used in the aperture of a downlight.
- Cord Cleat
Device used for most standard manual shades. The cord is wrapped around the cleat for safety reasons.
- Cove Lighting
Light built into a cove that illuminates the ceiling.
- Cross Lighting
Accenting an object from two directions to enhance the appearance of form; used effectively for sculpture and trees.
- Current
The flow of electrons through a wire; measured in amperes.
- Damp Location
UL Listing for fixtures used in a moist, but an unexposed area.
- Dark Skies
Refers to the International Dark Skies Association, which campaigns against light pollution. No fixture that emits light above horizontal.
- Dead End
End of a piece of track that is not receiving electric power.
- Diffuser
A light control device that spreads light by scattering it. Opal glass and plastic, etched glass, fabric, and paper act as diffusers.
- Dimmer
Control that varies the output of the light source by reducing the voltage or current to the lamp.
- DIP Switch
Miniature rocker-style switch that mounts to the circuit boards of electronic controls.
- Direct Current
Also known as DC. The continuous flow of electricity, as from a battery.
- Direct Lighting
Lighting that casts all, or at least 90%, of the light downward.
- Directional Lighting
Lighting that strikes an object or surface predominantly from a single direction. Generally used to include adjustable accent lighting using reflectorized sources.
- Downlight
A fixture that directs all light down.
- Driver
The term for the power supply that operates an LED lighting system.
- Duplex Outlet
A plug-in convenience receptacle for two plugs.
- Efficacy
Lamp efficacy is total lumen output divided by total watts consumed and is expressed Lumens Per Watt (LPW). Measures the energy efficiency of a light source.
- EISA
Energy Independence and Security Act of 2007. Law specifying the minimum efficiency of popular lamps and ballasts, including general service incandescent and linear fluorescent lamps, reflector lamps, and HID Ballasts.
- Electronic Dimmer
Dimmer that uses a solid-state switch (Triac) to turn off the current at a 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
Takes 120 Volts (line voltage) to 12 Volts (low voltage) using electronic switching rather than magnetic windings. Require special dimmers.
- Enclosed Downlight
Recessed fixtures enclosed at the bottom by a lens or diffuser. Produce medium beam spread.
- Energy Star
A program of the US Department of Energy and the Environmental Protection Agency. Qualifies lighting equipment and other appliances in terms of energy efficiency.
- 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.
- Exposed Conductor
Low voltage lighting system where the lighting elements are supported by uninsulated conductors.
- Fabric-Wrapped Fascia
Front surface of fascia is the same material as the roller shade. Used only on Triathlon wired or battery-operated shades.
- Fascia
L-shaped piece of metal that covers the front and bottom of a roller tube and fabric.
- Fiberoptic
A type of remote source lighting where light is conducted through transparent optical fibers from the source to an end fitting, and from the fitting into the space.
- Flap and Hanger
Flap and hanger are available to help finish the look of the large pocket with a fourth side that helps to hide the shade installation.
- Foot Candle
Also known as FC. Unit of illuminance – light falling on a surface or object. One lumen falling on one square foot equals one-foot candle.
- Four-Way Switch
Used with two three-way switches to allow a fixture to be controlled from three or more locations.
- Frensel Lens
A plano-convex lens that has been flattened into a disk or sheet to focus light into a beam.
- Furring
Spacer strips of wood or metal attached to wall studs or ceiling members to which surface material, such as wallboard, is fastened.
- Fuse
Replaceable safety device that provides circuit overload protection.
- Ganging
Mounting wall box dimmers or other devices together in the same enclosure and faceplate.
- Gimbal Ring
An adjustable ring that holds the PAR or MR lamp by its rim. A gimbal ring track fixture has no housing.
- Grazing Light
Directional light at an acute angle, which emphasizes texture. The sources of grazing light must be close to the surface.
- Greenfield
A flexible metal conduit that protects conductors.
- Grounding
Connecting electrical components to earth for safety.
- Hard-Edged Beam
Light pattern with sharply defined boundary, like that produced by a framing projector.
- Head rail
The top metal bar that’s on a roller shade.
- Heat Sink
The metal part that conducts heat away from LED, sensitive dimmer or fixture components to maintain cool operation.
- Hot Spot
A small area of higher illumination than the surrounding surface, typically produced by locating a light source too close to the surface or by the improper optical design of a fixture.
- Indirect Lighting
Lighting that directs all or most light upward for ambient or general illumination.
- Inside Mount
When a shade is secured to the inner part of a window’s frame.
- Insulated Ceiling Fixture
Recessed downlight suitable for direct burial in thermal insulation, called Type IC.
- IR Lamp
Infrared-Reflecting Halogen lamp using a special interior coating redirects infrared energy onto the filament, which increases output without added power.
- Junction Box
The enclosure that protects spliced wires and supports surface fixtures.
- Kelvin
A scientific unit of temperature.
- Lacquer
The clear coating that protects metal from rusting or tarnishing.
- Leaded Glass
Small pieces of glass joined at the edges with metal.
- LED
Also known as Light Emitting Diode, a small solid-state device that emits light by running small amounts of current through specially formulated semiconductors. They create light efficiently, produce little heat, last a long time, and contain no mercury.
- Lens
Transparent device for controlling light beams; bends rays of light to change the direction of the beam.
- Light Engine
An array of LEDs on a printed circuit board, sometimes including secondary optics and a driver.
- Light Filtering
Fabric that allows light to pass through it without significant darkening.
- Load
Lighting or other equipment controlled by dimmers.
- Local Transformer
Transformer associated with a single nearby fixture. They are not integrated into the fixture housing but supply only a single fixture.
- Louver
An array of baffles or reflectors that block light at certain angles and control glare.
- Low Voltage Fixtures
Recessed, track, task, decorative, or landscape fixtures for low voltage lamps. A transformer may be local, integral, or remote.
- Low Voltage Housing
Recessed housing with an integral transformer.
- Low Voltage Track
Track powered at low voltage by a step-down transformer (generally remote).
- Lumen
Unit of light output.
- Lumens Per Watt
Light output per unit of energy consumption.
- Lux
The metric unit of illuminance, equal to one lumen per square meter.
- Machine-Blown Glass
Shaped by mechanically forcing air into molten glass so that it takes the shape of the mold. Incandescent lamps are machine blown.
- Magnetic Ballast
Uses a magnetic (iron) core and copper windings to regulate the current that drives a lamp. Magnetic ballasts produce audible hi, and flicker. They are heavier and less efficient than electronic ballasts, but they cost less. They are no longer used in better quality fixtures.
- Magnetic Transformer
Uses magnetic (iron) core and copper windings to reduce line voltage (120 volts) to low voltage. Magnetic transformers produce audible hum. They are heavier and bulkier than electronic transformers but simpler and less costly to dim. Remote transformers over 300 watts are generally magnetic.
- Master
In dimming, the primary control location where you can set the scenes, fade rate, and other variables.
- Matte Finish
Matte finished surface produce a predominantly diffuse reflection, lightly textured, dull, not shiny.
- Mercury
An element used in a fluorescent lamp. When vaporized by the lamp’s arc, mercury emits the ultra-violet radiation that excites the lamp phosphors. Mercury is a toxic substance. It is harmless when contained in the unbroken lamp. You should specify low-mercury lamps and dispose of used fluorescent lamp properly to avoid mercury pollution.
- Mercury Lamp
An HID lamp, now largely obsolete.
- Metal Halide Lamp
A commercially popular HID lamp with a generally cool, white color. Ceramic meta; halide lamps enjoy high CRI are available in warm color and are increasingly used in retail and general architectural applications.
- Milk Glass
See Opal Glass
- Minimum Starting Temp.
The lowest temperature at which a fluorescent (and some HID) lamps can be started; varies by the lamp and ballast.
- Mogul Base
Used on high-wattage incandescent and HID lamps.
- Motion Detector
See Occupancy Sensor.
- Motorized
An automated shade that is operated by a remote, wall switch, or smart device.
- Mounting Height
The distance between the fixture and the surface.
- MR Lamp
Multi-faceted Reflector Lamp, the most popular of which is MR16. MR lamps surround a halogen capsule with a designed glass or metal reflector with many surfaces or facets. These compact lamps require a glass cover, either integral or with the fixture. Most MR lamps incorporate dichroic reflectors, which pass heat out the black of the lamp and reflect visible light forward in a cooler beam.
- Multi-Level Switching
Wiring and switches that permit you to create several levels of illumination, mostly used with non-dimmed fluorescent.
- Multi-Scene Control
Dimming system that creates several different settings (or scenes) for the lights in a room, generally using a push-button keypad.
- Nadir
Straight down below a fixture; used in photometry and designated as 0 degrees.
- Nanometer
One billionth of a meter; the wavelengths of light range from 380 to 780 nanometers.
- National Electrical Code
Sets of standards for wiring practice and the electrical devices used to implement them. The NEC requirements are widely followed by local jurisdictions, whose authority governs. The NEC is a private enterprise, not a Federal regulation!
- NEMA
National Electrical Manufacturers Association, which includes the lamp, electrical device, and larger fixture manufacturers. NEMA develops consensus ratings and designations for various products mostly commercial and industrial.
- Neodymium Lamp
Incandescent lamp with neodymium coating on the inside of the bulb. The neodymium absorbs just yellow light and so makes the light emitted from the lamp seem brighter and whiter. Other coatings can have the same effect.
- Neon Lamp
Low-pressure arc discharge lamps that operate at high voltage, similar to cold cathode.
- Network
A system of dimming controls that are wired and programmed to respond together, usually to link controls in several rooms.
- Neutral Conductor
Part of the circuit that carries the current “back” and completes the circuit. Compare to a “hot” or “switch” leg of the circuit.
- Nominal Watts
The power rating of lamps, as published by lamp manufacturers. Actual Input Power depends on the ballast used and includes the power consumed by the ballast, or ballast loss.
- Non-Dim
A dimming Zone or Channel set for on/off control only.
- Occupancy Sensor
Control that uses Passive Infrared or Ultrasonic detection to sense whether someone is present or not and to turn on or off appropriately. Automatic On sensors turn lights on when presence is sensed; Manual On sensors require you to press a switch. Both types turn lights off automatically when they no longer sense you.
- Opal Glass
Milky, translucent glass produced by adding ingredients to clear glass; used for diffusing light.
- Outside Mount
A window treatment that’s secured to the outside of the window frame.
- P-N Junction
Positive-Negative junction. The active region of a light emitting diode, where light is generated.
- PAR Lamp
Parabolic Aluminized Reflector Lamp. Constructed of hard glass, with a separate back reflector and front lens that are fused together. PAR lamps may be line or low voltage and can be used unprotected outdoors. Their beam patterns often have an uneven field.
- Parabolic Louver
A grid of parabolic-shaped reflector blades, either formed aluminum or molded, aluminized plastic, providing a highly efficient light shield in a recessed fluorescent troffer.
- 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 and many architectural fixtures.
- Passive Infrared Sensor
A detector that senses small movements in your thermal image; not “fooled” by wind or other false signals but requires a clear line of sight. See Ultrasonic.
- Pendant
Fixture suspended from the ceiling on cable, chain or stem. Pendant is also a term for a stem. Pendant Track is suspended on stems.
- Phase
In dimming, the portion of the alternating current that is switched. Forward phase (or leading edge) dimmers are used for incandescent and magnetic low voltage loads. Reverse phase (or trailing edge) dimmers are used for electronic low voltage and some LED loads.
- Phase
In dimming, the portion of the alternating current that is switched. Forward phase (or leading edge) dimmers are used for incandescent and magnetic low voltage loads. Reverse phase (or trailing edge) dimmers are used for electronic low voltage and some LED loads.
- Photocell
A light-sensitive device used to operate fixtures according to available daylight. Most often used to turn on outdoor or security lights at dusk and to turn them off a down.
- Photocell
A light-sensitive device used to operate fixtures according to available daylight. Most often used to turn on outdoor or security lights at dusk and to turn them off a down.
- Photometry
A light measurement. Used to rate lamps and to calculate the luminous distribution of fixtures and reflectorized lamps.
- Pinch Pleat
Pinched gatherings towards top of fabric.
- Pinhole
A recessed downlight that includes a faceplate, having a small aperture in it; used for inconspicuous accent lights.
- Plenum
The space between the ceiling and the floor or between the roof and the above.
- Pocket
Metal box used to house shades. Often mounted at / or above ceiling level.
- Point Source
A small source of light, such as most incandescent lamps. The term is also used to denote some fixtures, such as open downlights and track lights.
- Polycarbonate
Heat and shatter resistant plastic, usable indoors and out. Versatile polycarbonate can be transparent, translucent, or opaque.
- Polycarbonate
Heat and shatter resistant plastic, usable indoors and out. Versatile polycarbonate can be transparent, translucent, or opaque.
- Power Factor
The relationship between power consumption (watts) and current draw (amps) in an electrical device. The most efficient ballasts and transformers have a High-Power Factor (max is 1.0). Low power factor devices require additional circuiting and larger wires.
- Power Factor
The relationship between power consumption (watts) and current draw (amps) in an electrical device. The most efficient ballasts and transformers have a High-Power Factor (max is 1.0). Low power factor devices require additional circuiting and larger wires.
- Power Feed
Connection point that brings electricity to track and other lighting systems. Power feed may be at the end, floating, or at an intersection.
- Power Feed
Connection point that brings electricity to track and other lighting systems. Power feed may be at the end, floating, or at an intersection.
- Preheat Lamp
A fluorescent lamp that uses a starting switch to pre-heat the electrodes in to start the lamp. Most small compact fluorescent lamps are preheat types.
- Preheat Lamp
A fluorescent lamp that uses a starting switch to pre-heat the electrodes in to start the lamp. Most small compact fluorescent lamps are preheat types.
- Preset
Setting for a dimmer that can be selected without readjusting the dimmer intensity level each time; usually activated by a rocker or pushbutton. A preset scene is a setting for several channels or zones in a multi-scene dimming system.
- Preset
Setting for a dimmer that can be selected without readjusting the dimmer intensity level each time; usually activated by a rocker or pushbutton. A preset scene is a setting for several channels or zones in a multi-scene dimming system.
- 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.
- 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 fixture brightness.
- Quad-Tube Lamp
Single-ended compact fluorescent lamp consisting of two twin tubes on a single base.
- Quartz Lamp
Or quartz-halogen; terms for a Halogen Lamp. The term derives from the quartz glass capsule 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 reduces lamp life.
- R Lamp
Also known as reflector lamp. Soft-glass reflectorized lamp with a generally smooth distribution.
- Rated Life
See Average Rated Life.
- Receptacle
See Duplex Outlet.
- Recessed Fixture
Fixture mounted above the ceiling. With downlights, only the Aperture and Trim visible from below. With fluorescent troffers and luminous ceilings, only the covering is visible. Recessed fixtures provide direct downlighting.
- Recessed Fixture
Fixture mounted above the ceiling. With downlights, only the Aperture and Trim visible from below. With fluorescent troffers and luminous ceilings, only the covering is visible. Recessed fixtures provide direct downlighting.
- Reflectance
Percentage of light reflected from a surface.
- Reflectance
Percentage of light reflected from a surface.
- Reflected Glare
Glare from the Specular Reflection of bright light sources. You often experience reflected glare when looking at a computer screen, when reading a glossy magazine, or when working on a polished counter surface.
- Reflected Glare
Glare from the Specular Reflection of bright light sources. You often experience reflected glare when looking at a computer screen, when reading a glossy magazine, or when working on a polished counter surface.
- Reflection
Light bouncing off of a surface, not absorbed or transmitted. See also Specular Reflection
- Reflection
Light bouncing off of a surface, not absorbed or transmitted. See also Specular Reflection
- Reflector
Part of a fixture that redirects light to control brightness, beam spread, or intensity. Reflectors are frequently Specular, but may also be glossy, diffuse, or matte.
- Reflector
Part of a fixture that redirects light to control brightness, beam spread, or intensity. Reflectors are frequently Specular, but may also be glossy, diffuse, or matte.
- Reflector Trim
Finishing Section or Trim for a recessed downlight, which uses a reflector.
- 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. Reflectorized lamps produce directional beams. The varieties include PAR, R, MR, ER, AR, and other types.
- Reflectorized Lamp
Incandescent lamp with a reflector integrated into the envelope. Reflectorized lamps produce directional beams. The varieties include PAR, R, MR, ER, AR, and other types.
- Refraction
Bending light as it passes through a lens or prism to change the direction of the beam.
- Refraction
Bending light as it passes through a lens or prism to change the direction of the beam.
- Relay
Switch that accepts a low-power signal to control a high-power load.
- Relay
Switch that accepts a low-power signal to control a high-power load.
- Remodeler
Rough-In Section for a recessed downlight that is designed to install from below into a finished ceiling.
- 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 operation from multiple locations. Full-Function Remotes set the dimming level as well as switching on/off.
- Remote
Electronic control mounted separately from the master or individual dimmer, permitting operation from multiple locations. Full-Function Remotes set the dimming level as well as switching on/off.
- Remote Transformer
Separately mounted transformer that powers a low voltage fixture or system (indoors or landscape).
- Remote Transformer
Separately mounted transformer that powers a low voltage fixture or system (indoors or landscape).
- Ripple Fold
Consistent ripples created by drapery as the fabric hangs.
- Rods
Nerve endings in the “non-focal” area of the retina of the eye. Rods are very sensitive but see only black and white.
- Rods
Nerve endings in the “non-focal” area of the retina of the eye. Rods are very sensitive but see only black and white.
- Roman Shades
Shades that are drawn up from the bottom. They create horizontal folds when raised and they lay flat when they cover the window.
- Rough-In
The process of wiring a home and installing the Rough-In Sections of fixtures and the Back Boxes of electrical devices; precedes the finishing work.
- Rough-In
The process of wiring a home and installing the Rough-In Sections of fixtures and the Back Boxes of electrical devices; precedes the finishing work.
- Rough-In Section
UL term for the part of a recessed downlight that mounts to the building and connects to the electrical circuit. Housings, Cans, Frame-In Kits, Rough-Ins, and Rough-In Kits are all industry terms for the rough-in section. A Finishing Section attaches to the rough in; it provides the optics and trims out the ceiling.
- Rough-In Section
UL term for the part of a recessed downlight that mounts to the building and connects to the electrical circuit. Housings, Cans, Frame-In Kits, Rough-Ins, and Rough-In Kits are all industry terms for the rough-in section. A Finishing Section attaches to the rough in; it provides the optics and trims out the ceiling.
- Rust
Corrosion of metal, particularly iron and steel, from exposure to moist air and other elements; also called oxidation. Rust is a reddish-brown finish that can be produced by paint or chemical process.
- Rust
Corrosion of metal, particularly iron and steel, from exposure to moist air and other elements; also called oxidation. Rust is a reddish-brown finish that can be produced by paint or chemical process.
- Sand Casting
A process where molten metal is poured into a mold of compacted sand. The molds can be used only once. The process is costly, including finishing the rough casting.
- Sand Casting
A process where molten metal is poured into a mold of compacted sand. The molds can be used only once. The process is costly, including finishing the rough casting.
- Satin Finish
Slightly textured or brushed surface, having a fine grain, that reflects light with some diffusion.
- Satin Finish
Slightly textured or brushed surface, having a fine grain, that reflects light with some diffusion.
- Scallops
The arch-, or scallop-shaped pattern of light created when you locate a directional source close to a wall. See Wall Washer.
- Scallops
The arch-, or scallop-shaped pattern of light created when you locate a directional source close to a wall. See Wall Washer.
- Scene
Specific setting for a group of dimmers, channels or zones. A Multi-Scene Control allows you to select the different settings by pushing a button.
- Scene
Specific setting for a group of dimmers, channels or zones. A Multi-Scene Control allows you to 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.
- Sconce
Wall bracket derived from the form of a candelabra, often with exposed or decorative light sources.
- Service Entrance
Where electrical power from the public utility feeds into the home; location of the meter.
- Service Entrance
Where electrical power from the public utility feeds into the home; location of the meter.
- Silhouetting
Accent lighting technique that creates a dramatic outline by backlighting; used in landscape lighting.
- Silhouetting
Accent lighting technique that creates a dramatic outline by backlighting; used in landscape lighting.
- Single-Pole Switch
Operates a fixture or group of fixtures from one location.
- Single-Pole Switch
Operates a fixture or group of fixtures from one location.
- Skylight
A window that’s mounted inside a roof. They are horizontal or angled.
- Sleeve
Package for lamp, gives lamp designation code.
- Sleeve
Package for lamp, gives lamp designation code.
- Snoot
Tubular track accessory that cuts outside light and conceals the light source.
- Snoot
Tubular track accessory that cuts outside light and conceals the light source.
- Soffit
In architecture: the underside of an overhead component, such as an arch, cornice, beam, or balcony. Often used to describe an area of the ceiling that drops below the primary surface.
- Soffit
In architecture: the underside of an overhead component, such as an arch, cornice, beam, or balcony. Often used to describe an area of the ceiling that drops below the primary surface.
- Soft-White Lamp
Incandescent lamp with a dense, milky-white silica coating on the inside of the bulb; diffuses the light and completely conceals the lamp filament.
- Soft-White Lamp
Incandescent lamp with a dense, milky-white silica coating on the inside of the bulb; diffuses the light and completely conceals the lamp filament.
- Solid Brass
Fixture or parts made entirely of brass; in other words, not plated or simulated. Solid brass parts are “solid brass”, not “solid parts”; often, they are hollow castings and tubing.
- Solid Brass
Fixture or parts made entirely of brass; in other words, not plated or simulated. Solid brass parts are “solid brass”, not “solid parts”; often, they are hollow castings and tubing.
- Solid State
Electronics that use semiconductor chips and circuitry, rather than vacuum tubes. See Electronic Ballast, Electronic Dimmer, Electronic Transformer.
- Solid State
Electronics that use semiconductor chips and circuitry, rather than vacuum tubes. See Electronic Ballast, Electronic Dimmer, Electronic Transformer.
- Spacing Criterion/Spacing Ratio
For an even lighting pattern, the maximum distance between fixtures, as a function of their Mounting Height. Important for spacing downlights. Also called Spacing-to-Mounting Height Ratio and abbreviated S/MH. A S/MH of 0.7 indicates fixtures should be spaced no more than 5.6′ apart for even lighting on the floor from an 8′ ceiling.
- Spacing Criterion/Spacing Ratio
For an even lighting pattern, the maximum distance between fixtures, as a function of their Mounting Height. Important for spacing downlights. Also called Spacing-to-Mounting Height Ratio and abbreviated S/MH. A S/MH of 0.7 indicates fixtures should be spaced no more than 5.6′ apart for even lighting on the floor from an 8′ ceiling.
- Specification-Grade
Fixtures with construction and lighting performance suitable for institutional, better commercial, and premium residential applications. Generally larger, with higher wattage lamps, and costlier.
- Specification-Grade
Fixtures with construction and lighting performance suitable for institutional, better commercial, and premium residential applications. Generally larger, with higher wattage lamps, and costlier.
- Specular Finish
Highly polished and mirror-like. Semi-Specular Finish is generally bright but without a well-defined mirror image.
- Specular Finish
Highly polished and mirror-like. Semi-Specular Finish is generally bright but without a well-defined mirror image.
- Specular Reflection
The light bouncing off of a surface, so the angle of incidence equals the angle of reflection; creates a perfect, mirror image.
- Specular Reflection
The light bouncing off of a surface, so the angle of incidence equals the angle of reflection; creates a perfect, mirror image.
- Specular Reflector
Fixture component of highly polished metal, usually aluminum. Used in recessed downlights to produce the most efficient fixtures with the most comfortable apertures and least glare.
- Specular Reflector
Fixture component of highly polished metal, usually aluminum. Used in recessed downlights to produce the most efficient fixtures with the most comfortable apertures and least glare.
- Spot Lamp
Reflectorized lamp with a narrow distribution.
- Spot Lamp
Reflectorized lamp with a narrow distribution.
- Stamping
Inexpensive way to form sheet metal by hitting it with a die.
- Stem Mounting
Suspension by a rigid tube or rod, called a stem.
- Stop
A means of preventing a fixture from rotating past the desired point. This prevents wires from twisting or the fixture from aiming in the wrong direction.
- Strain Relief
Crimp or knot in wire or cord that prevents splices from pulling apart.
- Sustainable Design
Sustainable design aims to satisfy the needs of this generation while preserving the ability of future generations to satisfy their needs to the same degree- essentially by minimizing the impact on the natural environment. With respect to lighting, sustainable design emphasizes the use of daylight, energy-efficient electric lighting, lighting controls, and avoiding elimination of light pollution. The use of recycled and non-toxic materials is also important.
- Swag
Chain draped across the ceiling. A swagged pendant does not hang directly below its canopy.
- Switch Leg
Wiring that connects the switch or dimmer output to the fixture or load being controlled.
- Tap
Part of a transformer or a ballast that connects to the input or output wires. Low voltage transformers may have multiple taps on a switch, so they can provide several secondary voltages or handle several wattages at the same voltage. Landscape transformers often have high and low taps. HID ballasts usually provide multiple primary taps so one ballast can serve in a variety of conditions. See Transformer.
- Task Lighting
Localized light for specific visual activities.
- Tensioned Shades
Used for skylights, angled, bottom-up, and meet-in-the-middle applications. Maximizes the view by eliminating the cable guides typical of most skylight shades. A frame may be surface mounted, inside mounted, or recessed.
- Thermal Protector
A device that shuts off when fixture overheats or is improperly buried in thermal insulation. Some thermal protectors react only to the actual temperature; some react to both temperature level and heat gain. Recessed incandescent fixtures and fluorescent ballasts must be thermally protected.
- Three-Way Dimmer
Dimmer that works with a three-way switch for control from two locations; turns on/off and dims at the dimmer but only turns on/off at the switch.
- Three-Way Lamp
Incandescent lamp with two filaments that provides three levels of light when sequentially switched.
- Three-Way Switch
Operates a fixture from two locations. Also called a three-pole switch because it is connected to three wires: “hot” in, “switched” out, and a “traveler” to the other three-way switch.
- Tile Support Hanger
Hanger that seamlessly accommodates ceiling tile system by utilizing a hanger that protrudes to the room side and allows for hanger ceiling tile.
- Timer
A device that turns lights on and off at programmed times. See also Astronomical Clock.
- Tinted Glass
Clear glass with color added during manufacture; also, clear or opal glass coated with a thin film of colored glass or plastic.
- Toggle
Lever used for control, as in the common Toggle Switch or a Toggle Dimmer, which is designed to match.
- Top-Back Cover
Used to cover all four sides of a roller and minimize light leaks, fascia is paired with a top/back cover.
- Track Connector
The part that joins sections of electrified track.
- Track Lighting
System of electrified channel, or track, and movable lighting elements. Track is the most flexible approach to accent lighting.
- Transformer
A device used to raise (step up) or lower (step down) the voltage. Step down transformers reduce household voltage (120 volts) to low voltage used for accent and landscape lighting. Larger transformers reduce the high voltage used for efficient power distribution to safer and flexible household voltage. Input voltage is on the primary tap; output voltage is on the secondary tap.
- Transmission
Light passing through a material.
- Triac
Semi-conductor switch used in electronic controls.
- Trim
Confusing: sometimes the edge or visible part of a recessed downlight, as in “white trim”; sometimes the Finishing Section of the recessed fixture, as in “housing and trim”.
- Trim Ring
Plastic or metal ring on a recessed downlight that covers the cut edge of the ceiling hole.
- Triplex Glass
Three-layered glass consisting of clear, opal, or colored sandwiched between clear, all fused together. Triplex glass provides more luster and diffusion than homogenous colored or opal glass.
- Tungsten
Metal used to make the wire filament of incandescent lamps.
- Twin-Tube Lamp
Single-ended compact fluorescent lamp with the tube bent into a very tight “U” shape.
- U Lamp
Linear, double-ended fluorescent lamp, usually T8 or T12, bent into a “U” shape.
- UL
Underwriters’ Laboratories. A not-for-profit organization that works with the National Electrical Code to develop standards for electrical devices, wiring, and lighting fixtures. UL also tests fixtures and materials for compliance with the standards and lists fixtures for various applications, such as wet locations.
- Ultrasonic Sensor
Detects motion or occupancy by radiating high-frequency sound waves and noting any disturbance in the reflected waves. Ultrasonic sensors can detect motion over partial-height partitions because the sound waves bounce off the room surfaces but can be fooled rustling curtains or small animals.
- Ultraviolet Light
Also known as UV. This is light beyond the visible spectrum, having wavelengths from 10-380 nanometers.
- Universal
Common name for a plain track light that accepts a wide range of line voltage reflectorized lamps.
- Valance
A decorative board mounted at the top of the window to hide hardware and the frame.
- Valance Lighting
Fixture installed behind a longitudinal shielding member mounted over a window or along a wall; light is distributed up and down, usually fluorescent.
- Veneer
A thin sheet of material, usually wood or plastic, laminated to a core of stronger and less valuable material.
- Venetian Blinds
Blinds that are made up of either wooden or metal slats; they are attached to cloth tape and are maneuvered by cord on a pulley system.
- Volt
Unit of electrical force or pressure. Household voltage in the United States, nominally 120 volts, varies between 110-125 volts.
- Voltage Drop
The difference in voltage along a circuit. Voltage drop becomes a problem with low voltage wiring and small cable, reducing the intensity of lights at the far end of the cable.
- Wall Bracket
Fixture designed to be mounted on a vertical surface, including sconces, urns, and valances.
- Wall Lighting
Lighting directed on a wall or vertical surface to emphasize that plane, enhance the surface texture, or bounce light back into the room. Increasing wall brightness generally makes a room seem more spacious.
- Wall Washer
Fixture with special optics that direct light to the top of the wall and de-scallop the distribution on the wall.
- Wall Washing
Lighting a wall smoothly to reduce texture or specular reflection.
- Warm
Light that is tinted red, such as candles and flame. The term “warm” relate to how we feel about the light and the time of day and season to which it relates. In general, we prefer warm light for residential and warm interior spaces, intimate atmosphere, and low-intensity illumination.
- Watt
Unit of electrical power.
- Wave Length
Describes wave phenomena, like energy. Light is radiant energy with wavelengths from 380 to 780 nanometers. Each color of light can be described by its wavelength: red is 700-780 nanometers; yellow is 570-620 nanometers, etc.
- Weathered
Distressed finish that simulates aging.
- White Light
Combination of all colors of the spectrum; the light produced by common electric lamps. The color of white light is described by Color Temperature.
- Zone
In dimming, lights that are operated together. Also called Channel.
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- A-Lamp
The typical bulb-shared lamp with a screw base. The standard general service lamp; the most common incandescent household lamp.
- Accent Lighting
Localized and directional lighting used to highlight, focus attention and dramatize. Accent lighting fixtures include track, recessed, and specialty products.
- Acrylic
A translucent or transparent plastic, suitable for indoor or outdoor use. May be clear, opal, or colored. Does not yellow, but it is not shatter-resistant.
- Aged Finish
An oxidized finish, most often found on brass, to create a weathered appearance. Also called rust.
- Aiming Angle
How you point or direct an adjustable accent light. The aiming angle is calculated from vertical, or nadir. An aiming angle of 30 degrees is effective for paintings and drawings.
- Alloy
A mixture of two or more different metals.
- Alternating Current
Also known as AC. A current that reverses, or alternates, direction. Households use AC that alternates at 60 cycle per second.
- Alzak
Method of anodizing, a term for brightened, anodized aluminum.
- Ambient Lighting
Lighting that provides background brightness, so you can move around a space and that reduces the contrast between sources of local brightness.
- Ampere
Also known as Amp. Unit of electrical current. The rate of electricity flow and circuit capacity are stated in amperes.
- ANSI Designations
Designations for lamps established by the American National Standards Institute. ANSI also develops consensus standards for lamps, ballasts, and test procedures.
- Aperture
The opening of a fixture through which light exits.
- Architectural Lighting
A general reference to built-in lighting, such as recessed downlights, cove, and valences.
- Astronomical Clock
A clock programmed according to sunrise and sunset (seasonal) rather than 24-hour time. Used for timing controls.
- Average Rated Life
The number of hours required for half of a large group of lamps to fail or burn out. The actual life of any lamp or small group of lamps is typically different from the average rated life.
- Back Box
Fixture or electrical enclosure installed during the Rough-In phase of the project.
- Baffle
Part of the fixture that blocks light to prevent glare and control brightness. Often painted black to absorb light.
- Ballast
Electrical or electronic component required for fluorescent and HID lamps. They provide enough voltage to start the lamp and limit the current for continuing operation.
- Bath Bracket
The fixture used at a mirror or over a vanity. Ideally a long, well-diffused light source.
- Beam
The main part of the light distribution of a directional light source, accent light, or downlight.
- Beam Spread
The width of the beam in degrees. Beam spread is defined as the point where intensity falls to 50% of maximum candlepower.
- Bi-Pin Base
A lamp base with two pins. Used for some halogen lamps, most MR lamps, and fluorescent lamps.
- Bollard
Architectural outdoor fixture mounted low to the ground on a post for general or path lighting.
- Branch Circuit
Electrical circuit running from an electrical breaker panel.
- Brushed Finish
Satin, or lightly textured, finish produced by brushing with a wire wheel or buffering with a fine abrasive.
- Bulged Reflector Lamps
Also known as BR Lamps. Modified R lamp (see R Lamp) to meet the efficiency standards of EPACT. Produce a soft-edged beam that is less precise and narrower than those of PAR Lamps.
- Bullet
An accent light with a round back.
- BX Cable
Cable consisting of a flexible metal jacket surround two or more insulated wires.
- Caliper
Commercially available lighting performance evaluation report. A program of the US Department of Energy that tests LED products to assess how well measured performance compares to marketing claims and conventional alternatives.
- Candlepower
The intensity of light in a specific direction. Center beam candlepower is the intensity in the middle of the beam, generally the maximum intensity in a reflectorized lamp.
- Canopy
Fixture part that covers an outlet box or attachment point.
- Central Control
System for controlling all light from one or more locations. Also known as Home Control or Lighting Control/Automation.
- Channel
In dimming controls, a group of fixtures that are operated together. Also known as Zones.
- Circuit
Wiring path for electricity, including conductors, load, and circuit protection.
- Circuit Breaker
A protective device that automatically breaks the electrical path when overloaded. Located in the Electrical Panel.
- Color Rendering Index
Also known as CRI. A measure of how light sources render colors. The reference, CRI of 100, is a full spectrum source of the same color temperature as the lamp. The higher the CRI, the better the color rendering, given the color temperature of the lamp. Use at least 80 CRI for residential applications.
- Color Temperature
The appearance of white light, in terms of warmth or coolness. Color Temperature is measured using a Black Body and is shown in degrees Kelvin. Warm colors correspond to lower color temperatures and cool colors to warm color temperatures.
- Cone
Reflector used in the aperture of a downlight.
- Cove Lighting
Light built into a cove that illuminates the ceiling.
- Cross Lighting
Accenting an object from two directions to enhance the appearance of form; used effectively for sculpture and trees.
- Current
The flow of electrons through a wire; measured in amperes.
- Damp Location
UL Listing for fixtures used in a moist, but an unexposed area.
- Dark Skies
Refers to the International Dark Skies Association, which campaigns against light pollution. No fixture that emits light above horizontal.
- Dead End
End of a piece of track that is not receiving electric power.
- Diffuser
A light control device that spreads light by scattering it. Opal glass and plastic, etched glass, fabric, and paper act as diffusers.
- Dimmer
Control that varies the output of the light source by reducing the voltage or current to the lamp.
- DIP Switch
Miniature rocker-style switch that mounts to the circuit boards of electronic controls.
- Direct Current
Also known as DC. The continuous flow of electricity, as from a battery.
- Direct Lighting
Lighting that casts all, or at least 90%, of the light downward.
- Directional Lighting
Lighting that strikes an object or surface predominantly from a single direction. Generally used to include adjustable accent lighting using reflectorized sources.
- Downlight
A fixture that directs all light down.
- Driver
The term for the power supply that operates an LED lighting system.
- Duplex Outlet
A plug-in convenience receptacle for two plugs.
- Efficacy
Lamp efficacy is total lumen output divided by total watts consumed and is expressed Lumens Per Watt (LPW). Measures the energy efficiency of a light source.
- EISA
Energy Independence and Security Act of 2007. Law specifying the minimum efficiency of popular lamps and ballasts, including general service incandescent and linear fluorescent lamps, reflector lamps, and HID Ballasts.
- Electronic Dimmer
Dimmer that uses a solid-state switch (Triac) to turn off the current at a 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
Takes 120 Volts (line voltage) to 12 Volts (low voltage) using electronic switching rather than magnetic windings. Require special dimmers.
- Enclosed Downlight
Recessed fixtures enclosed at the bottom by a lens or diffuser. Produce medium beam spread.
- Energy Star
A program of the US Department of Energy and the Environmental Protection Agency. Qualifies lighting equipment and other appliances in terms of energy efficiency.
- 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.
- Exposed Conductor
Low voltage lighting system where the lighting elements are supported by uninsulated conductors.
- Fiberoptic
A type of remote source lighting where light is conducted through transparent optical fibers from the source to an end fitting, and from the fitting into the space.
- Foot Candle
Also known as FC. Unit of illuminance – light falling on a surface or object. One lumen falling on one square foot equals one-foot candle.
- Four-Way Switch
Used with two three-way switches to allow a fixture to be controlled from three or more locations.
- Frensel Lens
A plano-convex lens that has been flattened into a disk or sheet to focus light into a beam.
- Furring
Spacer strips of wood or metal attached to wall studs or ceiling members to which surface material, such as wallboard, is fastened.
- Fuse
Replaceable safety device that provides circuit overload protection.
- Ganging
Mounting wall box dimmers or other devices together in the same enclosure and faceplate.
- Gimbal Ring
An adjustable ring that holds the PAR or MR lamp by its rim. A gimbal ring track fixture has no housing.
- Grazing Light
Directional light at an acute angle, which emphasizes texture. The sources of grazing light must be close to the surface.
- Greenfield
A flexible metal conduit that protects conductors.
- Grounding
Connecting electrical components to earth for safety.
- Hard-Edged Beam
Light pattern with sharply defined boundary, like that produced by a framing projector.
- Heat Sink
The metal part that conducts heat away from LED, sensitive dimmer or fixture components to maintain cool operation.
- Hot Spot
A small area of higher illumination than the surrounding surface, typically produced by locating a light source too close to the surface or by the improper optical design of a fixture.
- Indirect Lighting
Lighting that directs all or most light upward for ambient or general illumination.
- Insulated Ceiling Fixture
Recessed downlight suitable for direct burial in thermal insulation, called Type IC.
- IR Lamp
Infrared-Reflecting Halogen lamp using a special interior coating redirects infrared energy onto the filament, which increases output without added power.
- Junction Box
The enclosure that protects spliced wires and supports surface fixtures.
- Kelvin
A scientific unit of temperature.
- Lacquer
The clear coating that protects metal from rusting or tarnishing.
- Leaded Glass
Small pieces of glass joined at the edges with metal.
- LED
Also known as Light Emitting Diode, a small solid-state device that emits light by running small amounts of current through specially formulated semiconductors. They create light efficiently, produce little heat, last a long time, and contain no mercury.
- Lens
Transparent device for controlling light beams; bends rays of light to change the direction of the beam.
- Light Engine
An array of LEDs on a printed circuit board, sometimes including secondary optics and a driver.
- Load
Lighting or other equipment controlled by dimmers.
- Local Transformer
Transformer associated with a single nearby fixture. They are not integrated into the fixture housing but supply only a single fixture.
- Louver
An array of baffles or reflectors that block light at certain angles and control glare.
- Low Voltage Fixtures
Recessed, track, task, decorative, or landscape fixtures for low voltage lamps. A transformer may be local, integral, or remote.
- Low Voltage Housing
Recessed housing with an integral transformer.
- Low Voltage Track
Track powered at low voltage by a step-down transformer (generally remote).
- Lumen
Unit of light output.
- Lumens Per Watt
Light output per unit of energy consumption.
- Lux
The metric unit of illuminance, equal to one lumen per square meter.
- Machine-Blown Glass
Shaped by mechanically forcing air into molten glass so that it takes the shape of the mold. Incandescent lamps are machine blown.
- Magnetic Ballast
Uses a magnetic (iron) core and copper windings to regulate the current that drives a lamp. Magnetic ballasts produce audible hi, and flicker. They are heavier and less efficient than electronic ballasts, but they cost less. They are no longer used in better quality fixtures.
- Magnetic Transformer
Uses magnetic (iron) core and copper windings to reduce line voltage (120 volts) to low voltage. Magnetic transformers produce audible hum. They are heavier and bulkier than electronic transformers but simpler and less costly to dim. Remote transformers over 300 watts are generally magnetic.
- Master
In dimming, the primary control location where you can set the scenes, fade rate, and other variables.
- Matte Finish
Matte finished surface produce a predominantly diffuse reflection, lightly textured, dull, not shiny.
- Mercury
An element used in a fluorescent lamp. When vaporized by the lamp’s arc, mercury emits the ultra-violet radiation that excites the lamp phosphors. Mercury is a toxic substance. It is harmless when contained in the unbroken lamp. You should specify low-mercury lamps and dispose of used fluorescent lamp properly to avoid mercury pollution.
- Mercury Lamp
An HID lamp, now largely obsolete.
- Metal Halide Lamp
A commercially popular HID lamp with a generally cool, white color. Ceramic meta; halide lamps enjoy high CRI are available in warm color and are increasingly used in retail and general architectural applications.
- Milk Glass
See Opal Glass
- Minimum Starting Temp.
The lowest temperature at which a fluorescent (and some HID) lamps can be started; varies by the lamp and ballast.
- Mogul Base
Used on high-wattage incandescent and HID lamps.
- Motion Detector
See Occupancy Sensor.
- Mounting Height
The distance between the fixture and the surface.
- MR Lamp
Multi-faceted Reflector Lamp, the most popular of which is MR16. MR lamps surround a halogen capsule with a designed glass or metal reflector with many surfaces or facets. These compact lamps require a glass cover, either integral or with the fixture. Most MR lamps incorporate dichroic reflectors, which pass heat out the black of the lamp and reflect visible light forward in a cooler beam.
- Multi-Level Switching
Wiring and switches that permit you to create several levels of illumination, mostly used with non-dimmed fluorescent.
- Multi-Scene Control
Dimming system that creates several different settings (or scenes) for the lights in a room, generally using a push-button keypad.
- Nadir
Straight down below a fixture; used in photometry and designated as 0 degrees.
- Nanometer
One billionth of a meter; the wavelengths of light range from 380 to 780 nanometers.
- National Electrical Code
Sets of standards for wiring practice and the electrical devices used to implement them. The NEC requirements are widely followed by local jurisdictions, whose authority governs. The NEC is a private enterprise, not a Federal regulation!
- NEMA
National Electrical Manufacturers Association, which includes the lamp, electrical device, and larger fixture manufacturers. NEMA develops consensus ratings and designations for various products mostly commercial and industrial.
- Neodymium Lamp
Incandescent lamp with neodymium coating on the inside of the bulb. The neodymium absorbs just yellow light and so makes the light emitted from the lamp seem brighter and whiter. Other coatings can have the same effect.
- Neon Lamp
Low-pressure arc discharge lamps that operate at high voltage, similar to cold cathode.
- Network
A system of dimming controls that are wired and programmed to respond together, usually to link controls in several rooms.
- Neutral Conductor
Part of the circuit that carries the current “back” and completes the circuit. Compare to a “hot” or “switch” leg of the circuit.
- Nominal Watts
The power rating of lamps, as published by lamp manufacturers. Actual Input Power depends on the ballast used and includes the power consumed by the ballast, or ballast loss.
- Non-Dim
A dimming Zone or Channel set for on/off control only.
- Occupancy Sensor
Control that uses Passive Infrared or Ultrasonic detection to sense whether someone is present or not and to turn on or off appropriately. Automatic On sensors turn lights on when presence is sensed; Manual On sensors require you to press a switch. Both types turn lights off automatically when they no longer sense you.
- Opal Glass
Milky, translucent glass produced by adding ingredients to clear glass; used for diffusing light.
- P-N Junction
Positive-Negative junction. The active region of a light emitting diode, where light is generated.
- PAR Lamp
Parabolic Aluminized Reflector Lamp. Constructed of hard glass, with a separate back reflector and front lens that are fused together. PAR lamps may be line or low voltage and can be used unprotected outdoors. Their beam patterns often have an uneven field.
- Parabolic Louver
A grid of parabolic-shaped reflector blades, either formed aluminum or molded, aluminized plastic, providing a highly efficient light shield in a recessed fluorescent troffer.
- 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 and many architectural fixtures.
- Passive Infrared Sensor
A detector that senses small movements in your thermal image; not “fooled” by wind or other false signals but requires a clear line of sight. See Ultrasonic.
- Pendant
Fixture suspended from the ceiling on cable, chain or stem. Pendant is also a term for a stem. Pendant Track is suspended on stems.
- Phase
In dimming, the portion of the alternating current that is switched. Forward phase (or leading edge) dimmers are used for incandescent and magnetic low voltage loads. Reverse phase (or trailing edge) dimmers are used for electronic low voltage and some LED loads.
- Phase
In dimming, the portion of the alternating current that is switched. Forward phase (or leading edge) dimmers are used for incandescent and magnetic low voltage loads. Reverse phase (or trailing edge) dimmers are used for electronic low voltage and some LED loads.
- Photocell
A light-sensitive device used to operate fixtures according to available daylight. Most often used to turn on outdoor or security lights at dusk and to turn them off a down.
- Photocell
A light-sensitive device used to operate fixtures according to available daylight. Most often used to turn on outdoor or security lights at dusk and to turn them off a down.
- Photometry
A light measurement. Used to rate lamps and to calculate the luminous distribution of fixtures and reflectorized lamps.
- Pinhole
A recessed downlight that includes a faceplate, having a small aperture in it; used for inconspicuous accent lights.
- Plenum
The space between the ceiling and the floor or between the roof and the above.
- Point Source
A small source of light, such as most incandescent lamps. The term is also used to denote some fixtures, such as open downlights and track lights.
- Polycarbonate
Heat and shatter resistant plastic, usable indoors and out. Versatile polycarbonate can be transparent, translucent, or opaque.
- Polycarbonate
Heat and shatter resistant plastic, usable indoors and out. Versatile polycarbonate can be transparent, translucent, or opaque.
- Power Factor
The relationship between power consumption (watts) and current draw (amps) in an electrical device. The most efficient ballasts and transformers have a High-Power Factor (max is 1.0). Low power factor devices require additional circuiting and larger wires.
- Power Factor
The relationship between power consumption (watts) and current draw (amps) in an electrical device. The most efficient ballasts and transformers have a High-Power Factor (max is 1.0). Low power factor devices require additional circuiting and larger wires.
- Power Feed
Connection point that brings electricity to track and other lighting systems. Power feed may be at the end, floating, or at an intersection.
- Power Feed
Connection point that brings electricity to track and other lighting systems. Power feed may be at the end, floating, or at an intersection.
- Preheat Lamp
A fluorescent lamp that uses a starting switch to pre-heat the electrodes in to start the lamp. Most small compact fluorescent lamps are preheat types.
- Preheat Lamp
A fluorescent lamp that uses a starting switch to pre-heat the electrodes in to start the lamp. Most small compact fluorescent lamps are preheat types.
- Preset
Setting for a dimmer that can be selected without readjusting the dimmer intensity level each time; usually activated by a rocker or pushbutton. A preset scene is a setting for several channels or zones in a multi-scene dimming system.
- Preset
Setting for a dimmer that can be selected without readjusting the dimmer intensity level each time; usually activated by a rocker or pushbutton. A preset scene is a setting for several channels or zones in a multi-scene dimming system.
- 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.
- 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 fixture brightness.
- Quad-Tube Lamp
Single-ended compact fluorescent lamp consisting of two twin tubes on a single base.
- Quartz Lamp
Or quartz-halogen; terms for a Halogen Lamp. The term derives from the quartz glass capsule 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 reduces lamp life.
- R Lamp
Also known as reflector lamp. Soft-glass reflectorized lamp with a generally smooth distribution.
- Rated Life
See Average Rated Life.
- Receptacle
See Duplex Outlet.
- Recessed Fixture
Fixture mounted above the ceiling. With downlights, only the Aperture and Trim visible from below. With fluorescent troffers and luminous ceilings, only the covering is visible. Recessed fixtures provide direct downlighting.
- Recessed Fixture
Fixture mounted above the ceiling. With downlights, only the Aperture and Trim visible from below. With fluorescent troffers and luminous ceilings, only the covering is visible. Recessed fixtures provide direct downlighting.
- Reflectance
Percentage of light reflected from a surface.
- Reflectance
Percentage of light reflected from a surface.
- Reflected Glare
Glare from the Specular Reflection of bright light sources. You often experience reflected glare when looking at a computer screen, when reading a glossy magazine, or when working on a polished counter surface.
- Reflected Glare
Glare from the Specular Reflection of bright light sources. You often experience reflected glare when looking at a computer screen, when reading a glossy magazine, or when working on a polished counter surface.
- Reflection
Light bouncing off of a surface, not absorbed or transmitted. See also Specular Reflection
- Reflection
Light bouncing off of a surface, not absorbed or transmitted. See also Specular Reflection
- Reflector
Part of a fixture that redirects light to control brightness, beam spread, or intensity. Reflectors are frequently Specular, but may also be glossy, diffuse, or matte.
- Reflector
Part of a fixture that redirects light to control brightness, beam spread, or intensity. Reflectors are frequently Specular, but may also be glossy, diffuse, or matte.
- Reflector Trim
Finishing Section or Trim for a recessed downlight, which uses a reflector.
- 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. Reflectorized lamps produce directional beams. The varieties include PAR, R, MR, ER, AR, and other types.
- Reflectorized Lamp
Incandescent lamp with a reflector integrated into the envelope. Reflectorized lamps produce directional beams. The varieties include PAR, R, MR, ER, AR, and other types.
- Refraction
Bending light as it passes through a lens or prism to change the direction of the beam.
- Refraction
Bending light as it passes through a lens or prism to change the direction of the beam.
- Relay
Switch that accepts a low-power signal to control a high-power load.
- Relay
Switch that accepts a low-power signal to control a high-power load.
- Remodeler
Rough-In Section for a recessed downlight that is designed to install from below into a finished ceiling.
- 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 operation from multiple locations. Full-Function Remotes set the dimming level as well as switching on/off.
- Remote
Electronic control mounted separately from the master or individual dimmer, permitting operation from multiple locations. Full-Function Remotes set the dimming level as well as switching on/off.
- Remote Transformer
Separately mounted transformer that powers a low voltage fixture or system (indoors or landscape).
- Remote Transformer
Separately mounted transformer that powers a low voltage fixture or system (indoors or landscape).
- Rods
Nerve endings in the “non-focal” area of the retina of the eye. Rods are very sensitive but see only black and white.
- Rods
Nerve endings in the “non-focal” area of the retina of the eye. Rods are very sensitive but see only black and white.
- Rough-In
The process of wiring a home and installing the Rough-In Sections of fixtures and the Back Boxes of electrical devices; precedes the finishing work.
- Rough-In
The process of wiring a home and installing the Rough-In Sections of fixtures and the Back Boxes of electrical devices; precedes the finishing work.
- Rough-In Section
UL term for the part of a recessed downlight that mounts to the building and connects to the electrical circuit. Housings, Cans, Frame-In Kits, Rough-Ins, and Rough-In Kits are all industry terms for the rough-in section. A Finishing Section attaches to the rough in; it provides the optics and trims out the ceiling.
- Rough-In Section
UL term for the part of a recessed downlight that mounts to the building and connects to the electrical circuit. Housings, Cans, Frame-In Kits, Rough-Ins, and Rough-In Kits are all industry terms for the rough-in section. A Finishing Section attaches to the rough in; it provides the optics and trims out the ceiling.
- Rust
Corrosion of metal, particularly iron and steel, from exposure to moist air and other elements; also called oxidation. Rust is a reddish-brown finish that can be produced by paint or chemical process.
- Rust
Corrosion of metal, particularly iron and steel, from exposure to moist air and other elements; also called oxidation. Rust is a reddish-brown finish that can be produced by paint or chemical process.
- Sand Casting
A process where molten metal is poured into a mold of compacted sand. The molds can be used only once. The process is costly, including finishing the rough casting.
- Sand Casting
A process where molten metal is poured into a mold of compacted sand. The molds can be used only once. The process is costly, including finishing the rough casting.
- Satin Finish
Slightly textured or brushed surface, having a fine grain, that reflects light with some diffusion.
- Satin Finish
Slightly textured or brushed surface, having a fine grain, that reflects light with some diffusion.
- Scallops
The arch-, or scallop-shaped pattern of light created when you locate a directional source close to a wall. See Wall Washer.
- Scallops
The arch-, or scallop-shaped pattern of light created when you locate a directional source close to a wall. See Wall Washer.
- Scene
Specific setting for a group of dimmers, channels or zones. A Multi-Scene Control allows you to select the different settings by pushing a button.
- Scene
Specific setting for a group of dimmers, channels or zones. A Multi-Scene Control allows you to 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.
- Sconce
Wall bracket derived from the form of a candelabra, often with exposed or decorative light sources.
- Service Entrance
Where electrical power from the public utility feeds into the home; location of the meter.
- Service Entrance
Where electrical power from the public utility feeds into the home; location of the meter.
- Silhouetting
Accent lighting technique that creates a dramatic outline by backlighting; used in landscape lighting.
- Silhouetting
Accent lighting technique that creates a dramatic outline by backlighting; used in landscape lighting.
- Single-Pole Switch
Operates a fixture or group of fixtures from one location.
- Single-Pole Switch
Operates a fixture or group of fixtures from one location.
- Sleeve
Package for lamp, gives lamp designation code.
- Sleeve
Package for lamp, gives lamp designation code.
- Snoot
Tubular track accessory that cuts outside light and conceals the light source.
- Snoot
Tubular track accessory that cuts outside light and conceals the light source.
- Soffit
In architecture: the underside of an overhead component, such as an arch, cornice, beam, or balcony. Often used to describe an area of the ceiling that drops below the primary surface.
- Soffit
In architecture: the underside of an overhead component, such as an arch, cornice, beam, or balcony. Often used to describe an area of the ceiling that drops below the primary surface.
- Soft-White Lamp
Incandescent lamp with a dense, milky-white silica coating on the inside of the bulb; diffuses the light and completely conceals the lamp filament.
- Soft-White Lamp
Incandescent lamp with a dense, milky-white silica coating on the inside of the bulb; diffuses the light and completely conceals the lamp filament.
- Solid Brass
Fixture or parts made entirely of brass; in other words, not plated or simulated. Solid brass parts are “solid brass”, not “solid parts”; often, they are hollow castings and tubing.
- Solid Brass
Fixture or parts made entirely of brass; in other words, not plated or simulated. Solid brass parts are “solid brass”, not “solid parts”; often, they are hollow castings and tubing.
- Solid State
Electronics that use semiconductor chips and circuitry, rather than vacuum tubes. See Electronic Ballast, Electronic Dimmer, Electronic Transformer.
- Solid State
Electronics that use semiconductor chips and circuitry, rather than vacuum tubes. See Electronic Ballast, Electronic Dimmer, Electronic Transformer.
- Spacing Criterion/Spacing Ratio
For an even lighting pattern, the maximum distance between fixtures, as a function of their Mounting Height. Important for spacing downlights. Also called Spacing-to-Mounting Height Ratio and abbreviated S/MH. A S/MH of 0.7 indicates fixtures should be spaced no more than 5.6′ apart for even lighting on the floor from an 8′ ceiling.
- Spacing Criterion/Spacing Ratio
For an even lighting pattern, the maximum distance between fixtures, as a function of their Mounting Height. Important for spacing downlights. Also called Spacing-to-Mounting Height Ratio and abbreviated S/MH. A S/MH of 0.7 indicates fixtures should be spaced no more than 5.6′ apart for even lighting on the floor from an 8′ ceiling.
- Specification-Grade
Fixtures with construction and lighting performance suitable for institutional, better commercial, and premium residential applications. Generally larger, with higher wattage lamps, and costlier.
- Specification-Grade
Fixtures with construction and lighting performance suitable for institutional, better commercial, and premium residential applications. Generally larger, with higher wattage lamps, and costlier.
- Specular Finish
Highly polished and mirror-like. Semi-Specular Finish is generally bright but without a well-defined mirror image.
- Specular Finish
Highly polished and mirror-like. Semi-Specular Finish is generally bright but without a well-defined mirror image.
- Specular Reflection
The light bouncing off of a surface, so the angle of incidence equals the angle of reflection; creates a perfect, mirror image.
- Specular Reflection
The light bouncing off of a surface, so the angle of incidence equals the angle of reflection; creates a perfect, mirror image.
- Specular Reflector
Fixture component of highly polished metal, usually aluminum. Used in recessed downlights to produce the most efficient fixtures with the most comfortable apertures and least glare.
- Specular Reflector
Fixture component of highly polished metal, usually aluminum. Used in recessed downlights to produce the most efficient fixtures with the most comfortable apertures and least glare.
- Spot Lamp
Reflectorized lamp with a narrow distribution.
- Spot Lamp
Reflectorized lamp with a narrow distribution.
- Stamping
Inexpensive way to form sheet metal by hitting it with a die.
- Stem Mounting
Suspension by a rigid tube or rod, called a stem.
- Stop
A means of preventing a fixture from rotating past the desired point. This prevents wires from twisting or the fixture from aiming in the wrong direction.
- Strain Relief
Crimp or knot in wire or cord that prevents splices from pulling apart.
- Sustainable Design
Sustainable design aims to satisfy the needs of this generation while preserving the ability of future generations to satisfy their needs to the same degree- essentially by minimizing the impact on the natural environment. With respect to lighting, sustainable design emphasizes the use of daylight, energy-efficient electric lighting, lighting controls, and avoiding elimination of light pollution. The use of recycled and non-toxic materials is also important.
- Swag
Chain draped across the ceiling. A swagged pendant does not hang directly below its canopy.
- Switch Leg
Wiring that connects the switch or dimmer output to the fixture or load being controlled.
- Tap
Part of a transformer or a ballast that connects to the input or output wires. Low voltage transformers may have multiple taps on a switch, so they can provide several secondary voltages or handle several wattages at the same voltage. Landscape transformers often have high and low taps. HID ballasts usually provide multiple primary taps so one ballast can serve in a variety of conditions. See Transformer.
- Task Lighting
Localized light for specific visual activities.
- Thermal Protector
A device that shuts off when fixture overheats or is improperly buried in thermal insulation. Some thermal protectors react only to the actual temperature; some react to both temperature level and heat gain. Recessed incandescent fixtures and fluorescent ballasts must be thermally protected.
- Three-Way Dimmer
Dimmer that works with a three-way switch for control from two locations; turns on/off and dims at the dimmer but only turns on/off at the switch.
- Three-Way Lamp
Incandescent lamp with two filaments that provides three levels of light when sequentially switched.
- Three-Way Switch
Operates a fixture from two locations. Also called a three-pole switch because it is connected to three wires: “hot” in, “switched” out, and a “traveler” to the other three-way switch.
- Timer
A device that turns lights on and off at programmed times. See also Astronomical Clock.
- Tinted Glass
Clear glass with color added during manufacture; also, clear or opal glass coated with a thin film of colored glass or plastic.
- Toggle
Lever used for control, as in the common Toggle Switch or a Toggle Dimmer, which is designed to match.
- Track Connector
The part that joins sections of electrified track.
- Track Lighting
System of electrified channel, or track, and movable lighting elements. Track is the most flexible approach to accent lighting.
- Transformer
A device used to raise (step up) or lower (step down) the voltage. Step down transformers reduce household voltage (120 volts) to low voltage used for accent and landscape lighting. Larger transformers reduce the high voltage used for efficient power distribution to safer and flexible household voltage. Input voltage is on the primary tap; output voltage is on the secondary tap.
- Transmission
Light passing through a material.
- Triac
Semi-conductor switch used in electronic controls.
- Trim
Confusing: sometimes the edge or visible part of a recessed downlight, as in “white trim”; sometimes the Finishing Section of the recessed fixture, as in “housing and trim”.
- Trim Ring
Plastic or metal ring on a recessed downlight that covers the cut edge of the ceiling hole.
- Triplex Glass
Three-layered glass consisting of clear, opal, or colored sandwiched between clear, all fused together. Triplex glass provides more luster and diffusion than homogenous colored or opal glass.
- Tungsten
Metal used to make the wire filament of incandescent lamps.
- Twin-Tube Lamp
Single-ended compact fluorescent lamp with the tube bent into a very tight “U” shape.
- U Lamp
Linear, double-ended fluorescent lamp, usually T8 or T12, bent into a “U” shape.
- UL
Underwriters’ Laboratories. A not-for-profit organization that works with the National Electrical Code to develop standards for electrical devices, wiring, and lighting fixtures. UL also tests fixtures and materials for compliance with the standards and lists fixtures for various applications, such as wet locations.
- Ultrasonic Sensor
Detects motion or occupancy by radiating high-frequency sound waves and noting any disturbance in the reflected waves. Ultrasonic sensors can detect motion over partial-height partitions because the sound waves bounce off the room surfaces but can be fooled rustling curtains or small animals.
- Ultraviolet Light
Also known as UV. This is light beyond the visible spectrum, having wavelengths from 10-380 nanometers.
- Universal
Common name for a plain track light that accepts a wide range of line voltage reflectorized lamps.
- Valance Lighting
Fixture installed behind a longitudinal shielding member mounted over a window or along a wall; light is distributed up and down, usually fluorescent.
- Veneer
A thin sheet of material, usually wood or plastic, laminated to a core of stronger and less valuable material.
- Volt
Unit of electrical force or pressure. Household voltage in the United States, nominally 120 volts, varies between 110-125 volts.
- Voltage Drop
The difference in voltage along a circuit. Voltage drop becomes a problem with low voltage wiring and small cable, reducing the intensity of lights at the far end of the cable.
- Wall Bracket
Fixture designed to be mounted on a vertical surface, including sconces, urns, and valances.
- Wall Lighting
Lighting directed on a wall or vertical surface to emphasize that plane, enhance the surface texture, or bounce light back into the room. Increasing wall brightness generally makes a room seem more spacious.
- Wall Washer
Fixture with special optics that direct light to the top of the wall and de-scallop the distribution on the wall.
- Wall Washing
Lighting a wall smoothly to reduce texture or specular reflection.
- Warm
Light that is tinted red, such as candles and flame. The term “warm” relate to how we feel about the light and the time of day and season to which it relates. In general, we prefer warm light for residential and warm interior spaces, intimate atmosphere, and low-intensity illumination.
- Watt
Unit of electrical power.
- Wave Length
Describes wave phenomena, like energy. Light is radiant energy with wavelengths from 380 to 780 nanometers. Each color of light can be described by its wavelength: red is 700-780 nanometers; yellow is 570-620 nanometers, etc.
- Weathered
Distressed finish that simulates aging.
- White Light
Combination of all colors of the spectrum; the light produced by common electric lamps. The color of white light is described by Color Temperature.
- Zone
In dimming, lights that are operated together. Also called Channel.
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- Arch Window
A window with a round portion and a flat portion. These shades are often referred to as “half-moons”.
- Bay Window
A window extending outward from a main wall; it forms a protrusion from the exterior wall.
- Bracket and Mounting Hardware
Hardware that holds the shade within the window’s frame.
- Cord Cleat
Device used for most standard manual shades. The cord is wrapped around the cleat for safety reasons.
- Fabric-Wrapped Fascia
Front surface of fascia is the same material as the roller shade. Used only on Triathlon wired or battery-operated shades.
- Fascia
L-shaped piece of metal that covers the front and bottom of a roller tube and fabric.
- Flap and Hanger
Flap and hanger are available to help finish the look of the large pocket with a fourth side that helps to hide the shade installation.
- Head rail
The top metal bar that’s on a roller shade.
- Inside Mount
When a shade is secured to the inner part of a window’s frame.
- Light Filtering
Fabric that allows light to pass through it without significant darkening.
- Motorized
An automated shade that is operated by a remote, wall switch, or smart device.
- Outside Mount
A window treatment that’s secured to the outside of the window frame.
- Pinch Pleat
Pinched gatherings towards top of fabric.
- Pocket
Metal box used to house shades. Often mounted at / or above ceiling level.
- Ripple Fold
Consistent ripples created by drapery as the fabric hangs.
- Roman Shades
Shades that are drawn up from the bottom. They create horizontal folds when raised and they lay flat when they cover the window.
- Skylight
A window that’s mounted inside a roof. They are horizontal or angled.
- Tensioned Shades
Used for skylights, angled, bottom-up, and meet-in-the-middle applications. Maximizes the view by eliminating the cable guides typical of most skylight shades. A frame may be surface mounted, inside mounted, or recessed.
- Tile Support Hanger
Hanger that seamlessly accommodates ceiling tile system by utilizing a hanger that protrudes to the room side and allows for hanger ceiling tile.
- Top-Back Cover
Used to cover all four sides of a roller and minimize light leaks, fascia is paired with a top/back cover.
- Valance
A decorative board mounted at the top of the window to hide hardware and the frame.
- Venetian Blinds
Blinds that are made up of either wooden or metal slats; they are attached to cloth tape and are maneuvered by cord on a pulley system.
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