Glossary

Definitions of common terms and acronyms you may encounter as a Christmas lighting enthusiast.

• Ambient Lighting
  Ambient lighting is lighting designed to create an overall atmosphere in a space. It typically consists of general, diffused light that provides a background illumination and acts as the main source of light in a room. Ambient lighting can come from natural sources such as sunlight or artificial sources such as overhead lights and wall ...
• Backlighting
  Backlighting is a technique used in Christmas lighting to create a glow around an object. It is accomplished by placing a light behind the object and point the light at the object, but the source of light obscured to a viewer on the opposite side of the object.
• Blacklight
  Black light, also known as ultraviolet (UV) light, is a type of electromagnetic energy which produces visible radiation in the UV spectrum. It is most often used in specialized applications such as halloween lighting displays, scientific research and photography.
• Bulb
  A bulb is a device that generates visible light when electricity passes through it. It consists of a glass bulb filled with a gas, typically an inert gas such as argon or krypton, and an electric filament. The filament is heated by the current running through it and emits light. Different types of light bulbs ...
• C Series
  C series describes the shape of a light bulb that is also known as candle, candelabra or cone. It is considered a vintage, retro upside down conical shape popularly used in Christmas lighting.
• Candela
  Candela is the unit of measurement used to measure the intensity of light radiation. It is defined as the amount of light energy per unit area, which is equivalent to one lumen per square meter. Candela is commonly used in lighting applications such as measuring the brightness of a light bulb or luminary.
• Candelabra
  A candelabra is a decorative piece of furniture that holds multiple candles. Typically, it consists of a vertical pole, usually made of metal, with several arms which can hold candles or other lights. Candelabras are traditionally seen in Christmas decorators, churches and religious ceremonies but have become increasingly popular in homes as an elegant lighting ...
• Cave Effect
  The cave effect is a phenomenon that occurs when artificial light from overhead fixtures are directed straight down, creating an unnatural and unappealing lighting environment. This type of lighting creates harsh shadows and deep contrast, as well as a feeling of discomfort and unease for those inhabiting the room. To avoid this effect, proper techniques ...
• Color Rendering Index (CRI)
  The Color Rendering Index (CRI) is used to measure the ability of a light source to accurately display colors when compared to natural light. Specifically, it evaluates how faithfully colors are displayed in comparison to sunlight by measuring eight color samples. On a scale from 0-100, the higher the CRI rating, the better the color ...
• Color Temperature (CT)
  Color temperature is a characteristic of visible light that has important applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields. It is expressed in Kelvin (K) using the Planckian locus – a visual plot of the spectrum of brightness and hue of different pure light sources. A lower color temperature indicates a more ...
• Cove Lighting
  Cove lighting is a type of indirect lighting that illuminates a space by hiding the light source. It is usually installed in or on a ceiling or wall and creates soft, rounded light that radiates across the room. Cove lighting is generally used to pair with other forms of direct and semi-direct lighting for a ...
• Cross Lighting
  Cross lighting is a type of lighting technique that utilizes two or more light sources at different angles in order to create depth and texture in an environment. This may involve combining direct and indirect forms of light and can be used to bring out certain elements of a space, such as paintings or furniture. ...
• Current
  In lighting, current is the flow of charged particles (electrons) through a conductor, such as a wire. Current is measured in amperes (amps or A), and the amount of current determines how much power is transferred through a circuit. Current is also what powers light fixtures, with higher currents resulting in brighter lights.
• Daisy Chain
  In lighting, a daisy chain is a wiring technique where multiple light fixtures are connected together in a line. This allows for multiple lights to be powered from one circuit, making them more efficient and easier to control. Daisy chaining also eliminates the need for additional wiring, as all the lights can draw power from ...
• Design Lights Consortium (DLC)
  The Design Lights Consortium (DLC) is a non-profit organization that works to promote energy efficiency in lighting. They develop standards for energy-efficient lighting products as well as provide guidance and incentives to help increase the use of these products. The DLC also sets guidelines and provides certification programs for both commercial and residential lighting products.
• Diffuse
  Diffuse is a type of lighting in which light is scattered equally throughout an area, giving it a uniform look. It is often used to create a soft and even illumination over a large area. Diffused lighting can be achieved through the use of frosted glass, screens, and other materials that scatter the light in ...
• Diffuser
  A diffuser is a device used to diffuse light. Diffusers are typically made from materials such as frosted glass, screens, or fabric, and are placed in front of lights to scatter the light in multiple directions and create a soft, even illumination. Diffusers also help to reduce hot spots, glare, and shadows in lighting setups.
• Dimmable
  Dimmable is a term used to describe lights or lamps that can be adjusted to different brightness levels. This can be achieved through the use of dimmers, which are devices that adjust the amount of electricity flowing to a light source and enable users to control its brightness. Dimmable lights are often used in lighting ...
• Dimmer
  A dimmer is a device used to adjust the brightness of a light or lamp. Dimmers can be installed in electrical circuits, and are typically operated by a knob or switch that controls the amount of power being sent to the light. Dimmers come in both digital and analog models, with digital models providing more ...
• Directional Lighting
  Directional lighting is a type of lighting that focuses light in one direction. It can be used for both task and accent lighting, and often creates directional shadows that can create interesting visual effects. Directional lighting typically involves the use of spotlights or directional lamps like track lighting and recessed lights. It is commonly used ...
• Downlight
  A downlight is a type of lamp or light fixture that shines light downward. Downlights are commonly used in homes, restaurants, offices, and other indoor spaces to provide ambient lighting. They are typically installed in recessed fixtures in the ceiling and have adjustable beams can be angled towards a specific area or wall. Downlights come ...
• Edison Bulb
  An Edison bulb is a type of light bulb that has a distinct, vintage style. It features a classic design that includes an exposed filament encased in clear glass, reminiscent of the bulbs used in the late 19th century and early 20th century by Thomas Edison himself. Edison bulbs are available in a variety of ...
• Efficacy
  In lighting, efficacy is a measure of how much light is produced per unit of energy used. It is typically measured in lumens (lm) per watt (W). The higher the efficacy, the more efficient the light source is and the lower energy costs it generates. LED lights are known for their high efficacy, with many ...
• Electroluminescent (EL)
  Electroluminescent (EL) lighting is a form of lighting technology that uses electric current to excite phosphors, causing them to emit visible light. It is relatively low power compared to other forms of lighting and can be produced in thin sheets or panels. EL lights are often used in displays and signage, as they provide an ...
• Elliptical Lens
  An elliptical lens is an optical element with a curved surface that has two focal points located on the same plane. In lighting, the design produces an asymmetrical distribution of light in one direction. This type of lens is most commonly used in imaging systems due to its ability to create an image with ...
• Energy
  Energy in lighting refers to the amount of energy that is used to power the lights. This energy can come from a variety of sources, including electricity, batteries, solar power and more. Lighting types such as LED and fluorescent bulbs require less energy to produce the same amount of light than traditional incandescent bulbs. The ...
• Energy Independence and Security Act of 2007 (EISA)
  The Energy Independence and Security Act of 2007 (EISA) is a federal energy law that promotes energy conservation and renewable energy. The Act seeks to enhance American energy security, reduce the nation’s dependence on foreign oil, mitigate global climate change, and create jobs. EISA mandated tighter fuel economy standards for motor vehicles, increased use of ...
• Energy Policy Act of 2005 (EPACT)
  The Energy Policy Act of 2005 (EPACT) is a federal energy law that seeks to promote energy efficiency and investments in alternative energy sources such as renewable wind, solar and biofuels. EPACT provides incentives for businesses to invest in clean energy technologies and offers various tax credits for the purchase of efficient appliances or vehicles. ...
• Energy Star
  Energy Star is a voluntary program run by the U.S. Environmental Protection Agency and Department of Energy that encourages businesses and consumers to save energy and money by using products that carry the Energy Star label. Products that bear the Energy Star label have met specific efficiency standards set by the EPA and are designed ...
• Fiber Optic
  Fiber optic lighting, also known as light piping or fiber optic illumination, is a type of lighting technology that uses strands of optical glass fibers to transmit light from a source to an illuminated object. Fiber optic lighting works by carrying light from a single source through tiny transparent fibers and dispersing it throughout an ...
• Filament
  Filament lighting is a type of incandescent lighting that uses an electric current to heat a thin wire filament until it starts to glow, emitting light. These bulbs are the most common form of light bulb found in households around the world. Filament lighting is generally considered inefficient due to its low luminous efficacy and ...
• Filter
  A lighting filter is a transparent material that can be placed in front of a light fixture or lens to alter the color and intensity of the emitted light. Filters are commonly used in photography and stage lighting to create dramatic effects, as well as in medical and scientific applications to reduce glare and improve ...
• Floodlight
  A floodlight is a type of light fixture that emits a wide, focused beam of light in order to illuminate larger areas than other types of lighting. Floodlights are commonly used for outdoor applications such as security lighting, sports arenas, stages and gardens. They can be either halogen bulbs or energy-efficient LED lights, with many ...
• Foot-Lambert
  Foot-Lamberts (fL) is a unit of measurement used to measure the luminance or brightness of an object. It is defined as one lumen per square foot and is commonly used in the imaging, video and projection industries. Foot-Lamberts are expressed as a ratio of light reflected off a surface, such as a movie screen or ...
• Footcandle
  Footcandles (fc) are a unit of measure for measuring the intensity of light. They refer to the amount of visible light that is produced by a single candle, one foot away from the source. Footcandles are essential for calculating the effectiveness and efficiency of lighting systems in commercial, residential, industrial and outdoor settings. Lighting designers ...
• Frequency
  In light, frequency refers to the number of times a wave repeats itself in one second. Frequency is commonly measured in hertz (Hz), which is equivalent to the number of cycles per second. Different types of lighting sources have different frequencies, which can affect how they appear when used for illumination or color-rendering purposes. For ...
• Frosted Lens
  A frosted lens is a translucent, semi-opaque material commonly used in lighting fixtures. It diffuses light and creates a softer glow than an unfrosted lens. Frosted lenses are often used in overhead lighting, such as track lighting and recessed lighting, as well as in decorative wall or ceiling fixtures. By softening the light output from ...
• Ganging
  Ganging is a term used to describe the process of connecting multiple fixtures together. This is often done in multi-light applications and can be accomplished either manually or with a specific ganging device. Manual ganging involves running cables from one fixture to another in order to create an independent system from multiple lights, while a ...
• Gobo
  A gobo is a stencil or template used in lighting to create patterns or textures from light. Gobos are typically made from metal, glass, or plastic, and act as a filter which allows only certain portions of the light passing through to reach the intended surface. Common applications for gobos include projection onto walls, floors, ...
• Illuminance
  Illuminance is the measure of light intensity on a surface or area. It is typically measured in lux, which is equal to one lumen per square meter. Illuminance can be described as the amount of light that falls on a surface and is usually referred to as brightness, though it should not be confused with ...
• Illuminating Engineering Society
  The Illuminating Engineering Society (IES) is a nonprofit organization that sets standards for lighting and other electrical equipment. Founded in 1906, the IES is an international professional organization dedicated to advancing knowledge of lighting through research, education, and professional development. The IES publishes recommended practice guidelines for many aspects of lighting technology, such as photometry, ...
• Incandescence
  Incandescence is the emission of visible light from a hot object. When an object’s temperature rises, it emits radiation in the form of visible light. This phenomenon is called incandescence and is one of the most important principles in lighting technology. Incandescent lights produce their light through a process called thermal radiation, which occurs when ...
• LED
  LED stands for Light Emitting Diode. It is a type of electronic semiconductor device which, when connected to an electrical circuit, produces visible light that can be used in lighting and display applications. LEDs are energy-efficient, long-lasting and do not emit harmful UV radiation like other lights.
• Light Trespass
  Light trespass is the movement of light from a light source onto a property or area which it was not intended to reach. It can be caused by point sources such as street lamps or floodlights, or from diffuse sources such as illuminated signs or bright interiors. Light trespass often results in glare, discomfort, and ...
• Lighting Facts Label
  A Lighting Facts Label is a label on a light product that provides information about the energy consumption and usage of the light. It is regulated by the Federal Trade Commission (FTC). The label includes information about brightness, power consumption, life expectancy, and other features to help customers make informed decisions when purchasing light products.
• Line Voltage
  Line voltage is the electrical potential difference between two points in a circuit. It is usually measured in volts (V) and is a measure of the pressure or force causing current to flow through an electrical circuit. Line voltage can be used to determine the correct power supply requirement for an appliance or device, as ...
• LRV (Light Reflectance Value)
  Light Reflectance Value (LRV) is a measure used in interior design and architecture to quantify the percentage of visible light reflected from a surface when illuminated by a light source. It is measured on a scale from 0 (absorbing all light) to 100 (reflecting all light). LRV is an important factor to consider when considering ...
• Photocell Sensor
  A photocell sensor is an electronic device which detects changes in light intensity and converts the light energy into electrical signals. It works by using semiconductors that react when exposed to changes in light, such as day turning to night. Photocell sensors are used for a variety of applications, including streetlights, automatic doors, motion sensors ...
• SPT
  SPT stands for Stranded, Parallel, Thermoplastic and refers to the amount of insulation on most flat wire. A number that follows this abbreviation indicates the thickness of the insulation. For example, STP-1 is of thinner insulation than SPT-2.