Lighting Term Glossary

A

AC	AC is an Acronym for alternating current. It is an electric current that reverses its direction many times a second at regular intervals, typically used in power supplies.

Accent Lighting	Light that focuses on a particular area or object. It is often used to highlight features such as art on a wall. Common types of accent lights include wall sconces, floodlights, recessed lights, or track lighting. The brighter light from the accent lamp creates visual interest in a space.

Ambient Lighting	Ambient lighting serves as the primary source of light for a certain room, often referred to as "general lighting". It is the foundation of all the lighting of a space. General lighting is used to provide visibility in a built environment. Ambient lighting includes both artificial and natural lighting.

Ampere (AMP)	Measurement unit for electric current. In lighting installations, wiring and protections are calculated based on the amperes drawn by the lighting circuits, as well as their rated voltage.

Amp Calculations	Procedure of determining the current drawn by a lighting fixture or a circuit consisting of multiple fixtures. Once the current drawn in amperes is known, it is possible to size the wire for the lighting circuit, as well as electrical protection devices.

Application	The intended use of a lighting product. Residential, Commercial, industrial. This is often referred to by a manufactuer to help assist installers and end users with assising a light fixtures suitability for an environment.

Architectural Lighting	A style of lighting design systems within the built environment, including both interior and exterior. The purpose of architectural lighting design is to balance the characteristics of light within a space to optimise the technical, the visual and ergonomics of illumination within a spaces.

B

Backlit	Lighting designed to illuminate an object from behind, which causes an appealing glow effect around its edges. Backlit luminares are often used as a type of accent lighting.

Ballast	A component required in fluorescent fixtures. It controls the voltage and electric current provided to the lamp during ignition and operation, preventing overheating or premature failure. Depending on their internal construction, ballasts can be either magnetic or electronic.

Base	The part of a lamp (Bulb) that connects to the lighting fixture, providing both physical support and electric power for the lamp. A common lamp base is Edison screw eg: E27, E14 etc)

Bayonet	A type of lamp base that connects with the socket using cross section bar (keyways) instead of threads. Bayonet are less common nowadays, Edison screw style has taken over in popularity.

Beam Angle	The beam angle of a lamp fixture is the angle at which the light is distributed or emitted. It is also known as beam spread,which describes the downward light cone emitted by a lighting fixture. Beam angle is an important metric to look at when designing lighting for a space. Beam angle will help determine how many luminares are required within a space to give you the optimium light spread you desire.

Bollard	A type of lighting fixture commonly used outdoors, consisting of a post with a lamp on top. Bollards provide both outdoor lighting and decoration.

Bulb	A transparent casing that contains a light source, generally made from glass. The 'offcial' term used by the electical industry is "lamp" both meaning the same.

C

Candela (cd)	A unit measurement for luminous intensity, which is the amount of light emitted in a particular direction. Not to be confused with the lumen (lm), measurement unit for the total lighting output of a lamp or fixture, without describing a particular direction.

Ceiling Cavity	The portion of a room that is above the lighting fixtures.

Chandelier	Derived from "chandler" (candle maker), a chandelier is a designer/decorative light that hangs from the ceiling and consists of several branch-like parts that host lights or candles.

Circline Lamp	A subtype of fluorescent lamp where a fluorescent tube is bent into a circular shape, and where the ballast is typically located in the middle.

Circuit Breaker	An electrical protection device for stopping the flow of current in an electric circuit as a safety measure. A circuit breaker is an electrical switch designed to protect an electrical circuit from damage caused by overcurrent/overload or short circuit. Its basic function is to interrupt current flow after protective relays detect a fault. Each lighting circuit is connected to a circuit breaker, and it interrupts current automatically if an overload or fault is detected.

Color Rendering Index (CRI)	Color Rendering Index (CRI) is the measurement of how vibrant colors look under a light source when compared with sunlight. The index is measured from 0-100, the higher the number the more vibrant colours will look. Most luminiares within NZ are built with a CRI80, CRI90+ is considered excellent and will provide great colour vibrance and clarity.

Compact Fluorescent Lamp (CFL)	A compact fluorescent lamp is an energy-saving light and compact fluorescent tube. It is a fluorescent lamp designed to replace an incandescent light bulb. This technology has now been further superseded by LED.

Cool White	A light source with a correlated color temperature of around 6000K. The term comes from the fact that light sources at this color temperature value do not have the characteristic yellow hue of incandescent bulbs or warm white LED lamps.

Correlated Colour Temperature (CCT)	Correlated Colour Temperature often referred to as "CCT" is lighting jargon that refers to the colour temperature of the light emitted from a LED luminaire. In New Zealand people often confuse CCT as "colour change temperature" refer "Tri Colour" for this definition.

D

DALI	Acronym for Digitally Addressable Lighting Interface, a communication protocol for lighting automation.

Daylight Harvesting	A lighting design strategy that maximizes the use of natural light to reduce energy costs and create indoor spaces that feel natural and appealing.

Daylight Lamp	A lamp with a CCT value comparable to that of daylight, generally between 5500K and 6500K. It is important to note that the term does not refer to actual daylight, but rather artificial lighting that replicates its color.

DC	Acronym for Direct Current. Used to describe a power supply where the flow of electricity always takes place in the same direction, such as that provided to LED arrays by their drivers.

Diffused Light	Light produced by an extended surface, either directly or through reflection. Diffused light provides a uniform and soft distribution that minimises shadows.

Diffuser	A piece of glass or acrylic that has the purpose of scattering the light from a bulb, which results makes lighting more uniform and eliminates glare.

Dimmable	Adjective used to describe a lamp fixture which can be used alongside a compatible dimmer. It is important to review the manufacturers recommended dimmers when a product is marked as "dimmable". Not all fittings and or lamps are compatible with all dimmers.

Dimmer	A device that regulates the lighting output lamp and or lamp fixture controlling the power supplied. It is important to note that not all lamps are compatible with dimmers, and incompatible types may be damaged.

Downlight	A recessed light or downlight is a light fixture that is installed into a hollow opening in a ceiling. A downlight front face will sit flush to the ceiling once installed.

Driver	Piece of electronic equipment that transforms the main supply voltage into a lower DC voltage that is appropriate for LED lighting. Some LED lamps have a built-in driver, while others require one to be connected externally, just like the ballasts used by fluorescent and HID lamps.

E

Efficacy	Describes how effectively a lighting fixture can convert electric power into lighting, measured in lumens per watt. The calculation for a light fixture efficacy is "lumen output"/"wattage" = X lumens per watt

Efficiency	Conversion ratio between lighting power output and electric power input, measuring both quantities in watts. Not to be confused with efficacy, which describes the ratio between lumen output and watts consumed. Since lumens describe lighting output better than watts, efficacy tends to be a much more useful concept in lighting design.

Electronic Transformer	Electronic Transformers are the newer style of technology on the market. They were originally produced as an economic alternative to wire wound transformers. They are generally smaller in physical size, offer less heat dissipation and have better energy efficiency relative to their price.

Emergency Lighting	Lighting designed to provide visibility when a normal lighting system fails, for example during blackouts or fires to assist people exiting a "space" safely. Emergency lighting is equipped with batteries, allowing it to operate long enough for a building to be evacuated.

F

Filament	The wire coil that produces light. Typically found in lamps (bulbs)

Floodlight	High-power lighting fixtures, generally used outdoors to light up specific areas and or features.

Frosted Lens	A white lens that is translucent but not transparent.

G

Glare	Visual impairment caused by a bright source of light, directly visible or reflected by a surface.

H

Hard Light	A light source that creates shadows with a very sharp edge when cast on objects. Direct lighting from a concentrated source is generally hard light, and some examples are: the sun in a day with clear skies, a camera flash, floodlight

Halogen Lamp	An improved version of incandescent lamps, where the glowing filament is contained in halogen gas, hence its name. Note: Halogen lamps have now been superceeded by LED technology

Heat sink	A lamp or luminaire component that is used to dissipate heat effectively. Heat sinks normally use materials with a high thermal conductivity and have a fin-like geometry so that their surface area in contact with the air is maximised.

High-Bay Lighting	Lighting systems designed for ceiling heights of 25’ or more, commonly found in warehouses.

I

IC-F	IC standard for "Insulation Contact" It is a lighting standard that refers to the installation requirement for this fitting. Soon to be replaced by the updated standard IC-4

IC-4	IC standard for "Insulation Contact" It is a lighting standard that refers to the installation requirement for this fitting. IC-4 is the newer standard soon to replace IC-F

Illuminance	The luminous flux on a surface, per unit of area. The illuminance requirements of built environments are determined by their intended purpose, and there are two common units of measurement: Lux - Equivalent to one lumen per square meter., Higher illuminance levels make surfaces appear brighter to the human eye and improve visibility.

Illumination	The use of lighting for practical or artistic purposes.

Incandescent Lamp	A type of lamp with a tungsten filament that glows when it carries current. Incandescent lighting has a perfect color-rendering index of 100, comparable to that of the sun, but is among the least efficient types of lighting.

Indirect Lighting	Lighting technique based on reflecting the output of a lamp on surfaces. An example is the lighting provided by torchiere fixtures, which emit their beam towards the ceiling to be reflected back down.

Integrated LED Fixture	A type of LED light fixture that has LED chips built into the fitting and can often not be replaced once the life of the LED is exceeded

Ingress Protection (IP) Rating	Ingress Protection rating, a two-digit code that indicates the resistance of a lighting fixture to solid particles and liquids, where higher digits indicate enhanced protection. The first digit indicates protection against solids, and the second indicates the protection degree against liquids.

K

Kelvin (K)	Measurement unit to indicate the colour of light emitted from an LED light fixture. Example: 3000k is a "warm white colour temperature"

Kilowatt (kW)	Measurement unit for electric power, equivalent to 1000 watts. This term should not be confused with kilowatt-hour.

Kilowatt-hour (kWh)	Measurement unit for energy consumption. As implied by its name, it is equivalent to the amount of energy consumed by a one-kilowatt appliance running for one hour. Electric utility bills are often calculated based on kilowatt-hour consumption per month. This term should not be confused with kilowatt.

L

Lamp	A lighting fixture that emits light. Often referred to as a "bulb"

Lamp Lumen Depreciation (LLD)	A progressive reduction in the luminous output of a lamp throughout it lifetime.

Lampholder	The part of a lighting fixture that provides support and power for a lamp with a matching base.

Light Layering	An interior design approach where several types of lighting are combined to achieve a specific ambience or mood.

LED	Acronym for light-emitting diode. The component inside LED light fixtures that emits the light output.

Light Loss Factor (LLF)	A factor used in lighting design to account of the degradation in luminous output over time. The LLF accounts for many aspects such as reflector or lens degradation, dust accumulation, lamp degradation due to voltage surges or heat, etc.

Light Pollution	Any lighting output emitted in unwanted directions, which may have negative consequences. An example of light pollution is when parking lot fixtures emit bright light sideways, exposing drivers to glare.

Light Scallops	An effect of placing light fixtures close to a wall creating light scallop pattens on a wall once the luminare is turned on.

Linear Lighting	Multiple light fixtures aligned in a single strip and used for creating uninterrupted lines of lighting.

Louver	A screen that blocks direct visibility of a light source and eliminates glare. Louvers are often seen on lighting products such as Bollards where light is wanted/needed on a downwards direction to prevent light glare of people passing.

Low Voltage Fixtures / Low Voltage Lamps	Lights that operate at a lower voltage than the standard household voltage of 230V. The most common low voltage fittings seen in NZ are either 12 or 24 volts. Low voltage is especially common in exterior garden lighting.

Lumen	Measurement unit for the lighting output of LED luminaires.

L70	Lumen Maintenance Life = L70, is a measure of the time taken for a light source to degrade to 70% of its original output. Measured in hours, it usually refers to degradation of total light output ie lumens. Note: The L70 does not dicate the end of a light fixtures light, just a reduction in it's overall light output performance.

Lumens per Watt	Lumens Per Watt (LPW) is the light output per unit of energy consumption and it reflects the lighting system's efficacy.

Lumens to Watts	The power (P) in watts (W) can be calculated by dividing the luminous flux (ΦV) in lumens (lm) by the luminous efficacy (η) in lumens per watt (lm/W).

Luminaire	A complete light fixture. A luminaire includes all functions to make it operational. EG: lamp, driver, internal wiring, reflectors, lens etc

Luminaire Dirt Depreciation (LDD)	Progressive reduction in the output of a luminaire due to dust accumulation.

Luminaire Efficiency	The ratio between the lumens emitted by a complete luminaire to those emitted by the lamps within. A portion of lighting is always lost due to internal geometric features and reflection. Not to be confused with luminous efficacy.

Luminous Flux	Total output emitted by a light source, measured in lumens. The luminous flux describes the total lighting output of a lighting fixture without considering direction. Not to be confused with luminous intensity.

Luminous Intensity	Lighting emission in a specific direction, measured in candelas. Luminous intensity changes depending on the viewing angle. Not to be confused with luminous flux.

Lux	Measurement unit for illuminance, or lumens per unit of area. One lux is equivalent to one lumen per square meter. A key component of lighting designed is achieving a suitable illuminance level depending on the application at hand.

M

Mounting Height	Depending on the application, mounting height can have two possible definitions: Distance between the bottom of the fixture and the work plane. Distance between the bottom of the fixture and the ground.

O

OLED	Acronym for organic light-emitting diodes, flexible polymers based on organic carbon molecules, where the light source is spread across a surface as opposed to a point source.

Opal Glass	Semi-translucent white glass that owes its milky finish to the ingredients added to clear glass. It is used for diffusing light.

Opaque Material	A material that completely blocks visible light.

P

PAR Lamp	PAR is an acronym for parabolic aluminized reflector, and it is used to shape the output of a light bulb into a directional beam. PAR lamps typically use incandescent, halogen or HID bulbs, and there are also LED replacements available. PAR lamps are available with both screw bases and pin bases.

Pendant Light /Pendant Lamp	A lighting fixture that is designed to hang from the ceiling, and which often uses a shade to prevent glare. Pendant lights can be used for both general and task lighting.

Photometry	The measurement of light and its properties.

Power Factor (PF)	Ratio of real power to apparent power drawn by lighting fixtures and other electrical devices. The real power is represented by the actual watts consumed, while the apparent power is the multiplication product of voltage and current, measured in volt-amperes. Electric utility companies normally apply additional charges if the power factor of a building drops below a specified level.

R

R9	The amount of red light, often missing in poor quality LED light fittings, leaving colours looking dull.

Rated Lamp Life	The time it takes for 50 percent of the lamps in a batch to reach the end of their service life.

Recessed Can	A specific type of lighting fixture with a cylindrical shape that is embedded in the ceiling, hence its name.

Recessed Luminaire	Also known as pot light, canister light or downlight, recessed lighting fixtures or luminaires are installed into the openings in a ceiling, appearing as if the light is shining from an elevated hole.

Reflector	An internal component of many lamps and luminaires. It has a reflective surface and its geometry is specially designed to provide a specific lighting distribution. Reflectors are often used with lamps that emit light rays in every direction (HID, fluorescent, etc.) to concentrate their output in a specific direction.

Retrofit	A lighting system upgrade, generally with the goal of improving energy efficiency and site safety.

S

Sconce	A wall-mounted lighting fixture, which generally has a decorative purpose.

Semi Flush	A ceiling lighting fixture that has a stem that separates (or creates a visible gap between) the light from the ceiling.

Shade	A screen that prevents a light source from being viewed directly. Shades generally use opaque or translucent materials.

Socket	See lampholder.

Soft Light	A light source that creates gradual shadows, without a noticeable edge between lighted and dark areas. Soft light is generally created with diffuse lighting sources, such as: The sun, when covered with clouds that diffuse its light. Lighting fixtures with lens or diffusers.

Spotlight	Lighting fixture that produces a narrow downward beam, generally used for accent lighting or task lighting applications.

SSL	Acronym for solid state lighting, any type of lighting that uses LEDs to produce light, instead of incandescent filaments, ignited gas or plasma. SSL includes OLEDs.

Step Dimming	Dimming method that uses incremental and fixed lighting levels, as opposed to gradual dimming from to OFF to 100% output.

Strip Light	Flexible, dynamic and customizable, strip lights can be cut and stuck anywhere, according to project requirements.

Suspended Light Fixture	See Pendant Light / Pendant Fixture / Pendant Lamp

T

Task Lighting	Lighting fixtures with the goal to improve visibility in an area where specific tasks will be carried out, hence their name. The use of under cabinet lights for food preparation areas in kitchens is an example of task lighting.

Total Cost of Ownership (TCO)	Cost of owning a lighting product over its entire lifetime. It includes the sales price, installation cost, energy consumption, maintenance, component replacements and decommissioning cost.

Track Lighting	Lighting configuration where several fixtures are mounted on a common track, which provides them with power and allows each of them to be oriented in a different direction.

Translucent Material	A material that allows a partial transmission of light, generally diffusing it and eliminating glare. Frosted glass is an example of a translucent material.

Transparent Material	A material that allows most or all of the light incident on it to pass through. Clear glass is a translucent material.

Troffer	A recessed lighting fixture, designed to be installed in an opening in the ceiling. Troffers typically have predetermined dimensions, such as 2’x2’ or 2’x4’.

Tri-Colour	Tri-Colour temporature is a function within a LED fitting that takes the guesswork out of choosing the right colour temperature at the time of purchase. Instead, you can now just buy the light fitting you need and make the colour temperature selection at the time of installation.

U

Ultraviolet Light	A type of electromagnetic radiation, invisible to the human eye (i.e., beyond the visible spectrum) with a wavelength of 10 to 380 nanometers.

Under cabinet lighting	Installed under a cabinet or shelf, this lighting is used to produce localized lighting and can also serve as a night light. It can come in LED, fluorescent, incandescent versions.

Uplighting	Lighting method where an object or surface is lit from below, with a luminaire that directs its output upward. The applications of uplighting are generally decorative.

V

Vanity Light	Lighting located above, below or to the sides of a bathroom mirror.

Voltage	The electric potential difference between two contacts. Voltage drives electric current through lighting fixtures and other appliances, just like pressure drives the flow of water in plumbing installations.

W

Wall Grazing	Lighting effect where a wall with an irregular surface is illuminated so that there are both highlighted and shaded areas. This effect is only possible on walls with granular surfaces, such as those built from stone or exposed brick. The opposite effect is wall washing.

Wall Sconce	See Sconce.

Wall Washing	Lighting effect where a wall is illuminated so that surface irregularities are minimized, it seem smoother. The opposite effect is wall grazing.

Warm White	White light that is characterized by a yellow tinge. The term is generally used for lighting with a correlated color temperature (CCT) of around 3000K.

Watt	Measurement unit for the electric power consumption of lighting fixtures, or any other appliance that runs with electricity. In lighting, lumens can be compared to miles traveled and watts can be compared to fuel consumption.

Watts to Lumens	To convert watts to lumens, multiply the power (P) in watts (W) with the luminous efficacy (η) in lumens per watt (lm/W).

Work Plane	The horizontal plane where activities are carried out, typically 30 inches above the floor. Lighting designs are generally based on providing a specified illumination level at the work plane.

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Lighting Term Glossary

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