GLOSSARY
A
A-Type Lamp
The “classic” light bulb, a pear-like shape typically fitted to the standard E26 socket. Your standard household light-bulb. “Edison bulb”. The number that follows the “A” designates the diameter of the bulb: ie A60/A19, A15, A50 etc.
Accent Lighting
Focuses light onto a specific area or object, creating an intended focal point for the viewer.
ADA Compliant
Meets requirements outlined by the American with Disabilities Act.
Adjustable Fixture
Fixtures that can be aimed, typically an accent light to illuminate a particular surface.
Aim
The direction in which light is projected from a fixture.
Alternating Current (AC)
An electric current which periodically reverses direction and changes its magnitude continuously with time.
Ambient Lighting
General lighting to be able to see within a space clearly, but not as functioning to light tasks and specific areas of detail.
Amp (A)
Shortened word for ampere – the measure of electrical current in units.
ANSI Code
A standardized coding system by the American National Standards Institute (ANSI) to classify various types of lamps (light bulbs) based on their shape, size, and other characteristics. Shows compatibility between lamps and fixtures and lamp replacement.
Antique
When a fixture has a classic, vintage look. Often using a finish that creates a distressed look to the fixture.
Aperture
The diameter of the opening of a luminaire where light enters a space. Typically 1-6in range for typical downlights.
Architectural Lighting
The strategic use of light in the design of buildings, physical structures, and spaces to enhance aesthetics, functionality, and ambiance.
Arm
Limb-like component mounted to a fixture core or light pole attaching to the fixture head thus supporting it.
Art Deco
A design and art style that emerged in the early 20th century, characterized by geometric shapes, sleek lines, vibrant colors, and ornate decorations, often associated with luxury and glamor.
Average Rated Life (ARL)
Hours required for half of a large group of lamps to fail or burn out.
B
Backlight
The illumination that comes from behind an object or subject, typically directed towards the camera or observer. It is often used to create a separation between the subject and the background, adding depth and highlighting the contours of the subject
Backlighting
A Lighting technique where the primary source of light is positioned behind the subject or object being illuminated.
Backplate
The part of a wall fixture that mounts to the wall.
Baffle
Part of the fixture trim that blocks light to prevent glare and control brightness.
Ballast
Essentially the heart of a fluorescent or HID that controls, regulates, and stabilizes the current flow and light output of the lamp.
Bank
An array or group of lights that are set up together. The lights in a bank may be arranged in a row, grid, or any other pattern to achieve a specific lighting effect.
Bare Ends/Leads
The exposed wire ends or conductors of a lighting fixture or electrical cable, often left unshielded or uncovered. Common in lamps or fixtures requiring a connection to a power source.
Barn Door
An accessory used with lighting fixtures to control and shape the direction of light.Typically mounted on the front of a fixture and consist of adjustable flaps (doors) to control the spread and shape of the light beam.
Base
Part of the light fixture that attaches to the surface (usually wall or ceiling).
Batten
A long, narrow fixture or housing that holds and supports fluorescent tubes or LED strips. Used in lighting applications to provide a linear and evenly distributed source of light.
Batwing Distribution
A light distribution pattern that is characterized by a wide and even spread of light, resembling the shape of bat wings. Provides uniform illumination over a broad area, making it suitable for applications where consistent lighting coverage is essential, such as street lighting or large open spaces to minimize shadows and maximize efficiency of the lighting spread.
Beam
The angle that light spreads from a light source where the intensity is at least 50% of the maximum intensity at the center/vertex of the light source.
Beveled Glass
Glass cut to a precise angle on the fixture surface to create a framed look.
Bleed
The unintentional spillover or diffusion of light beyond its intended area or boundary.
Bollard
A short, vertical post or pillar that serves both as a practical and decorative outdoor lighting fixture. These are commonly used in landscaping, pathways, and outdoor areas to provide low-level illumination and guide pedestrian or vehicular traffic.
Brightness
How an observer is able to distinguish differences in luminance through how they perceive light reaching the eye.
BUG Rating
Acronym for, “Backlight, Uplight, Glare”
Bulb
The replaceable, light-producing component of an electric lamp or lighting fixture. It typically consists of a glass envelope containing a filament or LED, and it produces light when an electric current passes through it.
Burn (In Light)
Melting of a lamp filament.
Busway
An electrical distribution system that consists of a prefabricated, enclosed conductor system for transmitting power. It typically involves a metal housing with conductive bars or busbars inside, providing a means to distribute electricity to lighting fixtures and other electrical devices.
C
Cable
A flexible, insulated conductor or a group of conductors used to transmit electrical power and signals between lighting fixtures and other electrical components.
Cable Drop
An electric cable(s) connected to an overhead support that extends downward connecting to a luminaire/fixture.
Can
Derived from “canister light”, this is a recessed lighting fixture’s can-shaped housing that is installed into a ceiling or wall, enclosing a light bulb or LED source. Used in downlighting for general illumination or accent lighting.
Candela
A unit of measurement that quantifies the intensity of a light source in a specific direction, to describe the brightness of a light source perceived by the human eye. It represents the luminous intensity in a particular direction of a light-emitting element, such as a lamp or a bulb.
Candelabra
A branched candle holder for multiple candles or lamps. Often associated with a chandelier.
Canopy
Plate attached to the ceiling to cover the hole of a fixture install and the junction box.
Casting
The intentional direction and control of light to achieve specific effects. It involves manipulating light sources, such as adjusting angles, using filters, or employing various tools, to create desired shadows, highlights, and overall illumination in a scene or setting.
Cave Effect
A lighting design technique that involves creating an environment where the light is focused and contained, similar to the effect of light within a cave. This often involves using specific fixtures and angles to produce controlled illumination, emphasizing certain areas while leaving others in shadow.
Ceiling Fixture
A lighting unit or device that is mounted or suspended from the ceiling. It is a broad term for many fixtures that provide overhead illumination such as pendant lights, chandeliers, and flush mount lights.
Chandelier
Decorative hanging light fixture, typically with several branches holding individual lamps or candles.
Channel
In lighting dimming controls – a group of fixtures that operate together, typically for the same function.
Circadian Lighting
Lighting designed to follow the human circadian rhythm, adjusting the color temperature and intensity of artificial light to mimic the natural changes in sunlight throughout the day. Supports overall well-being, influence sleep-wake cycles, and promote alertness by aligning artificial lighting with the body’s internal clock.
Color Perception
How our eyes perceive different colors based on the wavelengths of light that are absorbed or reflected by objects. The selective absorption or reflection of specific wavelengths by objects gives them their distinct colors.
Color Rendering Index (CRI)
An index on a scale of 1-100%, in which a light source reveals the true colors of objects and spaces illuminated in comparison to how a natural light source would display these. An example of a natural light source is the sun, which has a perfect index of 100%. Lower CRI light sources may make colors appear muted or faded on objects and spaces.
Concave
A surface or lens that curves inward, resembling the interior of a bowl or spoon.
Conductor
Anything that can carry electrical current, usually a wire.
Cone
A surface or reflector that curves inward, resembling the interior of a bowl. This shape can be found in certain lighting fixtures or reflectors designed to direct and focus light in specific ways.
Connector
Wiring devices attaching a conductor to each contact, insulating each contact from the next, and creating an assembly to make an electrical connection between two or more separate conductors.
Continuous Dimming
A lighting system that smoothly and gradually adjusts the light output across a wide range of brightness levels. Unlike stepped or incremental dimming, continuous dimming allows for a seamless transition between various light intensities, providing precise control over the lighting environment.
Convex
When the lens of a fixture is outwardly and spherically curved to distribute light more evenly or create a specific beam pattern.
Compact Fluorescent Lamp (CFL)
Utilizes a compact version of a fluorescent tube. These lights are designed with a coiled or spiral shape, making them more compact than traditional linear fluorescent tubes.
Controls
The mechanisms that turn a lamp(s) on and off. They can also regulate the dimming or color of the lamp. Common controls include switches, dimmers, timers, motion sensors, photosensors, and central control systems.
Correlated Color Temperature (CCT)
The color appearance of light in terms of warmth to coolness, measured temperature scale in degrees Kelvin. 2000K-3000K is “warm white”. 3100K-4500K is “cool white / bright white”. 4500K and beyond is “daylight”, mimicking natural daylight.
Cove Lighting
Lighting that illuminates onto the ceiling. Fixtures are hidden, usually within ledges, to create the surface glow that emphasizes the walls and ceiling features.
Crossbar
AKA a mounting bracket. A straight metal bar used to mount a fixture to a wall or ceiling, secured by a junction box.
Cutoff Angle
Viewing point at which it is no longer possible to see a light source directly.
D
Dali
Acronym for Digitally Addressable Lighting Interface. A lighting automation communication protocol.
Damp Location
When a fixture is rated to be located in an area potentially exposed to moisture. Indoors such as bathrooms or outdoors in a covered area is most common for damp location lighting.
Daylight Harvesting
A lighting control strategy that optimizes the use of natural daylight in a space using sensors and controls that adjust artificial lighting based on the amount of available natural light. The goal is to minimize energy consumption.
Dark Sky Compliant
Fixtures and lighting designs that adhere to principles aimed at reducing light pollution and minimizing the impact of artificial light on the night sky by minimizing upward light, glare, and unnecessary illumination.
Deck Lights
Lighting fixtures that are typically low-profile and installed directly onto the surface of the deck, serving both functional and decorative purposes by providing illumination for safety and ambiance in outdoor spaces.
Decorative Lighting
Lighting design through fixtures to help establish the tone and style of a room or space. Meant to be seen, often as a statement. Not usually the sole ambient lighting of a space.
Diffuser
An object that disperses light to filter the glare from the light source and create a glow. Softens highlights and shadows to reduce contrast and increase the beam spread.
Dimmable
The capability of a light source or fixture to be adjusted to various brightness levels allowing users to customize the lighting ambiance in a space. Often used to create different moods, save energy, or give flexibility in the user’s lighting design.
Dimmer Switch
Control used to manage the brightness of the light source. Usually a rotating or sliding switch to control from highest output dimming to the lowest output.
Die-Casted/Casting
Insert definition here…
Direct Current (DC)
Power supply where the flow of electricity is occurring in the same constant direction without cycling. Most commonly used in batteries and PV cells.
Direct Lighting
Lighting illuminated directly onto the object or space from the luminaire in which the light is sourced from.
Direct-Indirect Lighting
A lighting fixture or system that provides illumination both downward (direct) and upward (indirect). This design allows for a combination of task lighting and ambient lighting within a space.
Distribution
Pattern of light produced by a lamp or luminaire.
DMX Controls
Digital Multiplex system that transmits multiple digital signals at the same time.
Downlight
Luminaires that illuminate downward.
Driver
LED protecting computer that stabilizes the incoming electrical voltage and current to not go beyond the maximum voltage rating allowance.
Dry Location
When a fixture is rated to be located in an area that is not exposed to moisture or the outdoors.
Dusk-to-Dawn
Outdoor lighting fixtures or systems equipped with sensors that automatically turn on at dusk (when it gets dark) and turn off at dawn (when it becomes light). Providing illumination for safety, security, and energy efficiency.
E
Edison Base/Bulb
The standard socket or connector used for screw-in incandescent light bulbs. Named after the inventor Thomas Edison, this base is characterized by a screw thread design that allows bulbs to be easily screwed into compatible fixtures
Efficacy
How energy efficient a light source is. Lumens-per-watt ratio of power needed, calculated by the total light output (of a light source) divided by the total power input.
Electrical Circuit
A closed loop or pathway through which electricity flows, powering lighting fixtures or components. It consists of interconnected conductive elements, such as wires and electrical devices, forming a complete circuit.
Energy
The product of power in watts and time in hours.
Exterior Lighting
Illumination designed for outdoor spaces, including the lighting of building facades, landscapes, pathways, and other exterior areas. This type of lighting serves various purposes, such as enhancing safety, providing security, and creating aesthetic appeal.
F
Facade Lighting
Illuminating and highlighting the architectural features of a building’s exterior to enhance its aesthetics, create visual interest, and contribute to the overall nighttime appearance.
Fan
Typically refers to a ceiling fan with integrated lighting fixtures.
Filament
The thin wire inside an incandescent light bulb that emits light when heated by an electric current. The filament is usually made of tungsten and is housed within the bulb.
Finial
A decorative ornament or knob often found at the top or end of a lighting fixture, such as a lamp, chandelier, or decorative lighting pole head.
Finish
The surface treatment or coating applied to the external parts of a lighting fixture for the appearance. The finish contributes to the fixture’s outer color, style, and durability. Examples include polished, brushed, satin, matte, chrome, bronze, and paint colors.
Fixture
A complete lighting unit that includes a housing, socket, and often a shade or lens. This assembled product provides illumination for both functional and decorative purposes. Examples include ceiling fixtures, pendants, sconces, flood mounts, etc.
Floodlight
A high-intensity light designed to illuminate a large area or “flood” it with light using a wide beam angle, providing even and broad illumination. They are commonly used for security lighting, outdoor or sports events, and architectural accentuation on building facades or landscapes where an expansive light coverage is needed.
Fluorescent
Lighting that utilizes a phosphorescent coating and a low-pressure mercury vapor to produce visible light. The phosphor coating inside the tube emits light when excited by ultraviolet radiation produced by the ionized mercury vapor. Traditionally used for general illumination due to its energy efficiency, but modernly replaced by the LED light in the current industry and state of design.
Flush Distribution
A lighting pattern where the light is evenly and uniformly distributed across a surface without creating distinct shadows or concentrated beams to provide a smooth and consistent illumination.
Flush Mounting
Installation style where a fixture is mounted directly against a surface, such as a ceiling or wall, without protruding.
Footcandle (Fc)
Installation style where a fixture is mounted directly against a surface, such as a ceiling or wall, without protruding.
Four-way Switch
A type of switch or socket configuration that allows the user to control the light fixture from four different locations. Commonly used in larger rooms or spaces where multiple access points require control over the same light source.
Frosted
A surface treatment or coating that creates a diffuse and softened light output. These materials, such as glass or plastic, scatter and disperse light, thus reducing glare and creating a more even illumination.
G
Galvanized
A protective coating applied to metal surfaces, typically steel or iron, to prevent corrosion and rusting.
General Lighting
Glare
Excessive and uncomfortable brightness or intensity of a light occurring from a light source causing significant contrast between bright and dark areas in the visual field. Can cause visual discomfort, eye strain, or reduced visibility.
Globe
A spherical or rounded enclosure, typically made of glass or other transparent materials, that surrounds and protects a light source. Globes are commonly used as shades for various types of light fixtures, such as pendant lights or outdoor lanterns.
Gooseneck
A flexible and curved arm attached to a light fixture, resembling the neck of a goose.This type of fixture is commonly used in task lighting applications, such as desk lamps or outdoor signage lighting, where precise illumination direction is desired.
Grazing
A technique where light is directed at a low angle along or near a surface, typically a wall or textured facade, to highlight its features by creating shadows and emphasizing the texture and architectural details.
Grazing
A technique where light is directed at a low angle along or near a surface, typically a wall or textured facade, to highlight its features by creating shadows and emphasizing the texture and architectural details.
Grid Ceiling
A suspended or drop ceiling that is a secondary ceiling suspended below the main structural ceiling using a grid framework of metal or plastic channels. Commonly used to conceal ductwork, wiring, and plumbing while providing access to lighting fixtures and other building systems.
Grounding
The process of connecting electrical equipment, fixtures, or components to the ground or earth to prevent electrical shock, fires, or damage.
H
Halogen
A type of incandescent light bulb known for their bright and focused illumination, that uses a tungsten filament and a small amount of halogen gas to produce light with a longer lifespan than a traditional incandescent bulb.
Halo
A circular glow or ring of light that surrounds an object or light source. This effect is often intentional and can be achieved through various lighting techniques, such as using a halo light fixture or specific positioning of lights.
Hardwired
Method of electrical installation where the lighting fixture is directly connected to the building’s electrical system using permanent wiring. Hard-wired lighting installations are common in permanent fixtures such as ceiling lights, wall sconces, and built-in lighting systems.
Heat Sink
A component designed to dissipate and manage the heat generated by a light source, such as an LED. It is typically a metal structure or material that absorbs and conducts heat away from the light-emitting elements, helping to maintain optimal operating temperatures.
High Bay
Light fixture typically used in industrial or commercial applications. Mounted to ceilings that are 20 feet or higher from the ground.
Highlighting
See accent lighting.
High-Intensity Discharge (HID) Lamp
A type of lighting technology that produces light through the ionization of gas and the creation of an electric arc. HID lamps include various types such as metal halide, high-pressure sodium, and mercury vapor lamps.
High-Pressure Sodium (HPS) Lamp
HID light source in which radiation from sodium vapor under high pressure produces visible light.
Hot Spot
An area that is illuminated more than the surrounding surface from a light source. Usually a result of the lamp being placed too close to a surface, or at too high of an output, not allowing for a wide and even distribution.
I
Illuminance
The amount of light that falls on a surface per unit area. Measured in Footcandles (Fc) or Lux.
Incandescent Lamp
A type of light bulb that produces light by heating a wire filament to a high temperature until it emits visible light. The filament is usually made of tungsten. They have a simple design and were widely used for general lighting before the advent of more energy-efficient technologies used today such as LED.
Indirect Lighting
A type of lighting design or fixture where the light is directed in a way that it reflects off surfaces before reaching the area to be illuminated, typically creating a softer, diffused illumination and reduced glare and shadows.
Ingress Protection (IP) Ratings
Ratings of the degree of protection or sealing effectiveness for electronic equipment. This standard uses two numbers to define the rating. 1st digit – rates ingress of solids (ie “fingers, tools, debris, dust), 2nd digit – rates ingress of liquids. Ex: IP65 = Ingress Protection (IP) Dust-tight(6) Water Jet(5)
Initial Lumens
Total amount of light produced from a light source at the beginning of its life before depreciation has begun (with usage).
Input Power
The active power that is used by a lamp, measured in watts.
Intensity
The brightness or luminous power of a light source, measured in lumens. It indicates the amount of light emitted per unit of solid angle.
J
Junction Box
An electrical enclosure used to protect and contain electrical connections, such as wires or cables, within a lighting system.
Jelly Jar
A type of vapor-tight lighting fixture designed to protect the lamp and electrical components from moisture, dust, and other environmental contaminants.
Jumper Wire
A short length of electrical wire used to connect two or more terminals or components within a lighting circuit.
K
Kelvin
The SI Base unit of thermodynamic temperature, equal in magnitude to degrees Celsius. The degree used to measure the color temperature of a particular light source. A lower Kelvin is warm (2700K) and a high Kelvin is cool (5000K). The higher the Kelvin the whiter the light.
Key Light
The primary source of illumination used to illuminate the main subject or scene in photography, film, or stage productions.
L
Lamp
The light source that includes the bulb, base, and internal structure producing light. Commonly referred to as “light bulbs”. Also informally used to describe a plug-in luminaire (desk lamp, floor lamp, table lamp).
Lens
The part of a luminaire, often glass or plastic, used to control the distribution of light through the lamp.
Light
Radiant energy that is capable of producing a visual sensation.
Light Emitting Diode (LED)
A semiconductor device that emits light when an electric current passes through it. LED lighting is known for its energy efficiency, long lifespan, and versatility. It is often the most common lightsource used in new construction applications due to the energy efficiency compared to other, older light sources.
Light Meter
A lighting meter is a device used to measure various aspects of light, such as footcandles, intensity, illuminance, color temperature, and more.
Light Output
The total amount of visible light produced by a light source, measured in lumens.
Light Plot
A graphical representation that outlines the placement and configuration of lighting fixtures in a particular space or for a specific production, used as a guide for designers and electricians during installation and operation.
Light Source
A device or element that emits visible illumination by converting electrical energy, often through the use of a filament, gas, or semiconductor, into radiant energy in the form of light. Examples include incandescent bulbs, fluorescent tubes, LEDs etc.
Lighting Design
The process of planning, organizing, and implementing the use of light in a space to achieve specific objectives. It encompasses aesthetic, functional, and energy-efficient considerations to enhance visibility, accentuate architectural features, and contribute to the overall ambiance of a space.
Lighting Technique
The method used to light a space intended to achieve a desired look or effect.
Lighting Circuit
Electrical circuit that provides and controls the flow of electricity to lighting fixtures or devices. It typically includes components such as wiring, switches, fuses or circuit breakers, and the light fixtures themselves.
Load
The electrical power (usually in watts or kilowatts) consumed by lighting fixtures, representing the amount of energy drawn from the power source to illuminate the lights.
Louver
A series of baffles or reflectors used to shield, absorb, or reflect light from certain angles.
Lumen
Unit of luminous flux. The time rate of the flow of light.
Luminaire
A complete lighting fixture, including the light source, housing, and any necessary components for distributing and controlling the light. It is a designed unit that combines all elements required for illumination.
Luminaire Efficiency
Lumens emitted by a light fixture compared to the amount of lumens emitted by the actual lamp source within the fixture.
Luminance
The measure of the brightness of a surface as perceived by an observer, expressed in units of candelas per square meter (cd/m²). It is the amount of visible light emitted, reflected, or transmitted by a surface per unit of solid angle in a specific direction.
Luminous Flux
The total quantity of visible light emitted by a light source per unit of time. It is measured in lumens (lm). Luminous flux indicates the overall brightness of a light source, regardless of its direction
Lux
Standard unit of illuminance equal to 1 lumen per square meter.
M
Medium Base (for lamp)
An E26 Screw-in Base, also known as an Edison Base. The typical standard base for a lamp (bulb).
Mercury Vapor Lamp
A type of high-intensity discharge (HID) lamp that produces light through the ionization of mercury vapor. It contains an arc tube with mercury and a small amount of inert gas. This ionization is when an electric current passes through the arc tube, it ionizes the mercury, producing ultraviolet (UV) light. This UV light then interacts with phosphor coatings on the inner surface of the bulb, resulting in the emission of visible light.
Metal Halide Lamp
A type of high-intensity discharge (HID) lamp that produces light by passing an electric current through a mixture of metal halide gasses and mercury vapor. This interaction generates a high-intensity, white light.
Mounting Height
Distance from the floor to the center of the lamp within a luminaire or to the plane of the ceiling.
N
Narrow Beam
The angular spread of light emitted by a lighting fixture, typically ranging from 0 to 20 degrees. Produce concentrated light beams that are well-suited for spotlighting, accent lighting, or illuminating specific objects or architectural features.
Natural Light
Light that originates from the sun, providing illumination during daylight hours.
NEMA Code
Alpha-numeric code by the National Electrical Manufacturers Association (NEMA) for classifying and identifying electrical enclosures, including those used in lighting fixtures.
Nightlight
A small, low-intensity light fixture designed to provide gentle illumination during the nighttime hours. Commonly in bedrooms and hallways for safety, security, and comfort.
Non-Dimmable
A light fixture or lamp that is not compatible with dimming controls and cannot be adjusted to change light output or intensity within its fixed brightness level.
O
Open Circuit
An electrical circuit in which there is a break or interruption in the continuity of the conductive path, preventing the flow of electricity.
Open End
A type of lamp holder or socket where one end of the lamp is exposed and not enclosed by a fixture or housing, allowing easy maintenance or replacement.
Open Face
A lighting fixture design where the lamp or light source is exposed and not covered by a diffuser, shade, or other enclosure. Allow direct visibility of the light source and can provide a more direct and focused illumination.
Optics
Components such as lenses, reflectors, diffusers, and louvers used to control and manipulate the distribution, intensity, and quality of light emitted by lighting fixtures.
Outdoor Lighting
Fixtures and systems designed for exterior environments, such as outdoor spaces, landscapes, building exteriors, and pathways.
Outlet
A socket or receptacle installed in a wall or ceiling that provides electrical power for plugging in lighting fixtures or other electrical devices.
Output
See light output.
P
Parabolic
Refers to a fixture or reflector with a paraboloid shape designed to focus and direct light efficiently, producing a controlled and even illumination.
Pendant
A suspended luminaire hung from the ceiling, often used as a decorative element.
Phosphor
Chemical compound used to coat the inside of a fluorescent lamp and some HID lamps.
Photocell/Photosensor
A device that detects ambient light levels and triggers the operation of lighting fixtures based on changes in natural light. When the ambient light decreases to a certain level (typically at dusk or in low-light conditions), the photocell activates the connected lighting, and when the light increases (typically at dawn or in brighter conditions), it deactivates the lighting, thus optimizing energy usage.
Photometry
The measurement and analysis of light characteristics, such as intensity, distribution, and color by using techniques and instruments to quantify how light behaves in a given environment or from a specific light source.
Plenum
The space above a dropped ceiling or below a raised floor that is used for air circulation in a building’s HVAC system (heating, ventilation, and air conditioning). Lighting fixtures installed in plenum spaces must meet specific safety and code requirements to ensure they do not contribute to the spread of fire or contaminants.
Power Factor
A measure of the efficiency of electrical power utilization in lighting systems. It indicates the ratio of real power (watts) to apparent power (volt-amperes), with a higher power factor indicating more efficient power utilization.
Programmable Lighting
Lighting systems or fixtures that can be programmed to automatically adjust light levels, color temperatures, or lighting scenes based on predetermined schedules, user preferences, or environmental conditions.
Q
Quality of Light
The characteristics of light that affect the visual appearance and perception of a space, object, or scene. It encompasses factors such as color rendering, color temperature, uniformity, glare, flicker, and distribution.
R
Range
In lighting, this is the distance over which a beam of light is projected and the diameter of that beam.
Recessed Luminaire
A luminaire that is mounted above the ceiling, wall, or other surface where mounted. The opening of the luminaire is flushed (flat) with the surface mounted on.
Reflectance
How much light is reflected by a surface. It quantifies the percentage of incident light that is bounced back from a surface, affecting the overall brightness and appearance of a space.
Relamp
The process of replacing existing lamps (light bulbs) in lighting fixtures with new ones.
Relay
An electrical switch that is used to control the flow of electricity to lighting fixtures or circuits. It is typically activated by a separate control signal, such as a switch, timer, or sensor, allowing it to turn lights on or off remotely or automatically based on predetermined conditions.
Response Time
The duration it takes for a lighting system or device to react to a stimulus or command, such as turning on or off in response to a switch or sensor input.
Retrofit
The process of upgrading or modifying existing lighting fixtures or systems to improve performance, energy efficiency, or functionality.
S
Safety Switch
A device designed to interrupt the flow of electricity to lighting fixtures in the event of an electrical fault or hazardous condition, such as a short circuit or overload.
Saturation
The intensity or purity of a color produced by a light source. It describes the vividness or richness of a color, with highly saturated colors appearing more vibrant and intense.
Sconce
A wall-mounted light fixture with the source typically directed up, down, or both, for both functional and decorative purposes. Often used for ambient, task, or accent lighting and commonly found in hallways, bedrooms, living rooms, and corridors.
Service Life
The expected duration of time that a lighting fixture or lamp (light bulb) is anticipated to operate reliably before needing replacement, typically expressed in hours of use or operation.
Shade
A covering or enclosure typically made of materials such as fabric, glass, or metal, which is used to diffuse, direct, or control the distribution of light emitted by a lamp or fixture.
Skylight
A window or opening in a roof structure that allows natural light to enter an indoor space from above.
Socket
The electrical component that holds and connects the light bulb or lamp to the electrical supply within a lighting fixture.
Soffit
The underside of an architectural element, such as a ceiling, roof overhang, or archway. Involves fixtures installed within or facing downward from this underside to provide illumination for architectural accents, pathways, or outdoor spaces.
Soft Edge
A gradual transition between illuminated and shadowed areas, resulting in a gentle and diffused boundary. Uses lighting techniques such as diffusion materials, feathered light sources, or precise positioning to create smooth and natural-looking gradients of light and shadow.
Specification Grade
Lighting fixtures or products that meet higher standards of quality, performance, and durability compared to standard-grade products.
Spill
Unwanted or excess light that extends beyond the intended target area or surface. When light falls outside of the designated illumination zone, causing glare, reducing contrast, or causing light pollution.
Strobe
An effect that produces brief flashes of light at regular intervals. They can create various visual effects, such as freezing motion, simulating lightning, or enhancing the perception of movement.
Surface Mount
A light fixture is mounted directly onto a surface, such as a wall or ceiling, without the need for recessing or embedding it into the structure.
Surge
A sudden increase in voltage in an electrical circuit, often caused by lightning strikes, power surges, or electrical faults.
Suspended Luminaire
See pendant.
Switch
A device used to control the flow of electricity to lighting fixtures, allowing them to be turned on or off.
T
Task Lighting
Illumination specifically designed to provide focused and directed light for performing specific activities or tasks. It is strategically positioned to minimize glare and shadows, enhancing visibility and reducing eye strain.
Three-Way Switch
A type of electrical switch that allows control of a single light fixture from two different locations. It enables users to turn the light on or off from either switch position, providing flexibility and convenience in lighting control.
Throw
The distance over which a beam of light is projected from a lighting fixture. It describes how far the light travels from the source to illuminate a specific area or object.
Tilt
The ability of a lighting fixture to be adjusted or angled vertically, allowing for changes in the direction of the light beam.
Timer
A device used to automatically control the operation of lighting fixtures based on predetermined schedules or time intervals. Timers can be programmed to turn lights on or off at specific times, helping to save energy, enhance security, and provide convenience for users.
Track Lighting
A lighting system where multiple light fixtures, known as track heads, are mounted onto a linear track. The track is typically attached to the ceiling or wall and contains electrical conductors that supply power to the fixtures. Track lighting allows for adjustable positioning and aiming of the light fixtures along the track, providing flexibility in illuminating specific areas or objects
Transmission
The passage of light through a material or medium, such as glass, plastic, or fabric.
Trim
The component that surrounds the opening of a recessed lighting fixture. Trims serve both aesthetic and practical purposes, providing a finished appearance and helping to direct or control the distribution of light emitted by the fixture.
Troffer
A rectangular lighting fixture typically recessed into a suspended ceiling grid. Commonly used in commercial and institutional settings such as offices, schools, and healthcare facilities to provide general illumination
Truss
A framework typically made of metal or aluminum that is used to support and hang lighting fixtures, audio equipment, and other stage elements.
Tungsten-Halogen Lamp
A type of incandescent lamp that contains a tungsten filament enclosed in a small transparent quartz envelope filled with a halogen gas, such as iodine or bromine.
U
U-Shaped Lamp
A type of fluorescent lamp that has a bent or curved shape resembling the letter “U.” These lamps are designed to fit into fixtures that require a compact form factor while providing efficient illumination.
UL Listing
UL, Underwriters Laboratories. Products that have passed the safety and material tests conducted by Underwriters Laboratories.
Ultrasonic Motion Detector
A sensor that detects motion by emitting ultrasonic waves and measuring their reflection off of nearby objects. When motion is detected within the detection range of the sensor, it triggers a response, such as turning on or off lighting fixtures.
Ultraviolet (UV) Radiation
A type of electromagnetic radiation with wavelengths shorter than those of visible light, typically ranging from about 100 to 400 nanometers. While invisible to the human eye, ultraviolet (UV) radiation has various applications in lighting, including sterilization, material curing, and inducing fluorescence in certain materials.
Under-Cabinet Lighting
A type of lighting fixture installed beneath cabinets or shelves to provide illumination to countertops, workspaces, or other areas below.
Uplight
Light directed upward to create ambient lighting, enhance the perception of space, and add visual interest to a room by highlighting architectural features or creating indirect illumination.
V
Vanity Light (or sconce)
A wall-mounted fixture located next to a mirror to provide task lighting for the mirror user.
Vapor Tight
A fixture is a lighting fixture designed to protect the lamp and electrical components from moisture, dust, and other environmental contaminants.
Vanity Light
Lighting fixtures specifically designed for use in bathrooms or dressing areas to provide adequate illumination for grooming tasks such as applying makeup or shaving.
Vibration Resistant
Fixtures designed to withstand mechanical vibrations and shocks without experiencing damage or premature failure. Commonly used in industrial and outdoor applications where vibration from machinery or environmental conditions may be present.
Voltage (V)
The electrical potential difference between two points in an electrical circuit, measured in volts (V). It represents the force or pressure that drives electric current through a conductor, such as wires or cables, and powers lighting fixtures.
W
Wall Box
An electrical enclosure or housing installed within a wall to contain and protect electrical wiring and devices, such as light switches, outlets, or lighting controls.
Wall-Washing
A lighting technique wherefixtures are positioned to uniformly illuminate a vertical surface, such as a wall or architectural feature. The goal is to create a smooth and even distribution of light across the surface, minimizing shadows and emphasizing textures or details.
Warm Dimming
When fixtures are able to change both their color temperature and brightness as they are dimmed. As the light dims, it shifts to a warmer, more amber-like color temperature, similar to the dimming effect of traditional incandescent bulbs. Often used in human-centric lighting to benefit our circadian rhythm.
Watt (W)
Unit of active electric power; the rate at which electric energy is consumed.
Wattage
Amount of power consumed or produced by an electrical device or system, typically measured in watts (W).
Wavelength
A fundamental property of light waves, specifically electromagnetic waves, that describes the distance between two consecutive points in a wave that are in sync with each other.
Y
Yoke
A U-shaped bracket or arm that is attached to the body of a lighting fixture, allowing it to be mounted and positioned on various supports such as poles, trusses, or stands.
Z
Zone Lighting
A lighting design technique where a space is divided into different zones or areas, each illuminated independently to provide tailored lighting levels and ambiance.