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Accent Lighting: Directional lighting used to emphasize a particular object a specific location or area.
Acid: Anti Copying in Design: an international action group which fights copyright theft.
Alternating Current (AC): The flow of electricity which travels in waves and pulses on and off in cycles many times per second. The number of cycles per second is referred to as frequency. The most common frequency of electricity used in the UK is 50-1000 and is the US is 60 hertz (cycles per second).
Ambient Lighting: also known as freLighting designed to provide general uniform illumination throughout the work area.
Amp: (SEE Ampere) A common abbreviation for Ampere.
Ampere: The standard unit of measurement for electric current that is equal to one coulomb per second. It defines the quantity of electrons moving past a given point in a circuit over a period of time.
Ampmeter: A device used to measure the flow of current in an electrical circuit.
Anodized: An electrolytic process for converting an aluminum surface to aluminum oxide. Anodizing creates a transparent finish that is physically part of the metal. Anodized finishes are generally colorless, but may be dyed in a variety of colors. The coating is hard and highly resistant to corrosion.
Application: This term refers to how a product is used; i.e., a vandal-resistant fixture in a prison is a good "application" of this particular product.
ASID: American Society of Interior Designers
Back Plate: A bracket on a surface or wall mounted luminaire used to fasten the luminaire and to cover the outlet box.
Baffle: A shield of metal, wood or plastic used to screen a light source from normal angles of viewing. Aluminum baffles are commonly used in parabolic fixtures. OR, A grooved cylinder dropped below a light source to conceal the lamp and provide light cutoff.
Battery: A chemical device that provides DC (direct current) voltage. It is a source of electrical energy.
Breaker: An electromechanical device that acts as a switch-and- fuse combination to protect and disconnect a circuit in case of an overload or short circuit
CAD: Acronym for Computer-Aided Design. A method of designing and drafting interactively (and graphically) using a computer system. This saves time and labor, especially for revision work
Can (Low End): Jargon for an inexpensive (low-end) downlighting product that is recessed into the ceiling. Called a "can" or "pot" because of its shape.
Candela: Unit of luminous intensity, describing the intensity of a light source in a specified direction.
Candlepower: Older terminology for luminous intensity; the intensity in candelas of light from a source.
Capacity: The allowable volume of amperage for a feeder at its particular current carrying capacity. Each conductor is sized, giving it a certain capacity to feed current to a load.
Circuit: A completed path of electrical elements including the electric source, the wiring and the load.
Compact Fluorescent: Twin-tube fluorescent lamp used in some Emergency Lighting, Downlighting, and Fluorescent products. The lamp life is about 10 times that of incandescent lamps and uses less power. Also referred to as "PL", "Twin-Tube", or BIAX lamps.
Conductor: A substance or material (typically wire) capable of carrying electric current.
Conduit: A metal tube or "pipe" used as an enclosure to protect electrical conductors; also a type of electrical raceway.
Cord Set: Electrical cord with attachment plug which is built into the fixture so that it may be plugged into a standard electrical outlet.
Coulomb: A unit of electrical charge equal to 6.24 x 10 (to the 18th power) electrons.
Current: The flow of electrons in an electrical circuit (measured in amperes)
Die-Cast: A metal molding process where hot molten metal is injected into a "hard" mold. After the molten metal hardens and cools, it is removed and trimmed to complete the finished part
Diffuse: Term describing the lack of directionality in light distribution. Refers to the scattering of light.
Digital Dimmer: Dimmer controlled directly by a series of computer generated digital signals.
Dimmer: A device which changes lighting intensity by regulating electrical power delivered to the lamp.
Dimming System: An arrangement of cabinets containing multiple dimmers operated from remotely mounted control stations. The two are normally connected with low voltage control wires.
Direct Current (DC): Flow of continuous electricity in one direction from positive to negative.
Direct/Indirect Lighting: A variant of general diffuse lighting in which the luminaires emit little or no light at angles near the horizontal.
Directional Lighting: Lighting provided on the work-plane or on an object predominately from a particular direction.
Discharge: The removal of stored energy in a battery.
Disconnect Socket: (CIRCUIT-INTERRUPTING LAMPHOLDER) - Prevents shock by de-energizing the electrodes in the sockets when the lamp is removed. Used with dimming ballasts and emergency lighting.
Downlight: A type of point source ceiling luminaire, usually fully recessed. May feature an open reflector or may incorporate a shielding or directing device.
Dual Circuit: Refers to a branch circuit configuration in which two hot conductors are used with one or two neutral conductors as a grounding conductor to form a circuit.
Dual Circuit Switching: Two circuits in one area that are switched to a given level.
Dual Voltage: A fixture or product having the capability to operate by either 277 or 120 voltage. A fixture or product having the capability to operate at two differing supply voltages.
Efficacy: A metric used to compare light output to energy consumption. Efficacy is a ratio of lumens to watts and can be defined for bare lamps or for luminaires.
Efficiency: The ratio of the lumen output of the luminaire to that of the bare lamp.
Electrolyte: The chemical fluid used in batteries which supplies electrons.
Energy-Saving Lamp: A type of lamp designed to operate more efficiently, producing more lumens per watt than standard lamps, and thus operates at a lower wattage than a standard lamp.
Façade Lighting: This term typically refers to the exterior of a building and the lighting of the vertical building surface. This is usually accomplished with floodlights or spotlights or ground mounted landscape luminaries.
Fade Rate: Time required for a dimmer to change from one intensity level to another. Fade rates may be either user adjustable or factory set. Normally used with PRESET SCENE control.
FC: The English unit of measurement of the illuminance onto a surface. One footcandle is equal to one lumen per square foot.
Fenestration: Any opening or arrangement of openings that allows daylight into a room.
Filter: Electrical components within a dimmer intended to reduce the effects of EMI and lamp filament hum.
Fixture Schedule: A construction document that lists all luminaires used on a particular job. The list typically includes fixture, type, fixture catalog number, fixture quantity, lamp type, lamp catalog number, ballast type and voltage. (Also known as luminaire schedule).
FL: Unit used in lighting to describe the luminance of an area. Today, it is more common to use candelas per meter squared (Candela/meters squared). This term is still occasionally referred to as footlamberts.
Flange: Overlapping metal portion of a recessed luminaire at the ceiling line. It serves to trim the ceiling opening around the luminaries.
Fluorescent: A linear light source consisting of a tube filled with gas. When electrical current is applied, the resulting arc emits ultraviolet light that excites the phosphors on the inside of the lamp wall, causing them to radiate visible light.
Footcandle (FC): The English unit of measurement of the illuminance onto a surface. One footcandle is equal to one lumen per square foot.
Footlambert (FL): Unit used in lighting to describe the luminance of an area. Today, it is more common to use candelas per meter squared (Candela/meters squared). This term is still occasionally referred to as footlamberts. 1 fL = 0.3183 (1/pi) cd/feet squared.
Four-Way Switch: A type of switch that is always used in conjunction with two three-way switches and which allows three or more entrances into a room to be switched.
Fresnel Lens: A lens consisting of an array of concentric circular prisms that may be used to focus, collimate, or spread light.
Fuse: An electrical safety device, made of wire or thin metal, and usually enclosed in glass, that will melt and "break" the circuit in the event of a current overload.
General Diffuse Lighting: Lighting from luminaires that distribute 40% to 60% of its emitted lumens downward and the balance upward.
General Lighting: Lighting designed to provide essentially uniform illumination throughout the work area exclusive of any provision for any special, localized requirements.
Glare: The effect of brightness or brightness differences within the visual field sufficiently high to cause annoyance, discomfort or loss of visual performance.
Grazing: Downlighting or uplighting indoor or outdoor application used to show texture on surfaces, walls and fabrics.
Grommet: A rubber insulating eyelet used to prevent water entry into the fixture at the wire exit.
Halogen: Gas used in tungsten-halogen lamps which increases lamp life and enhances lumen output.
Housing: The body of a fixture.
HVAC: Abbreviation for Heating, Ventilation and Air Conditioning.
IALD: Abbreviation for International Association of Lighting Designers.
IC: Abbreviation for Insulated Ceiling. Any ceiling that has insulation material.
Ignitor: A device that generates a voltage pulse to start certain discharge lamps without having to pre-heat the electrodes.
Illuminance: A photometric term which quantifies light striking a surface or plane at a point. It is expressed either in lumens per square foot, footcandles (the English metric) or lumens per square meter, lux (the metric unit). 1 footcandle = 10.76 lux.
Indirect Lighting: Lighting by luminaires that distribute 90 to 100% of the emitted light upward.
Inductor: An electrical circuit component (essentially a coil of wire) that stores energy in an electromagnetic field.
Initial Lumens: The lumen output of a lamp after about 100 hours of operation.
Insertion Loss: A lowering of the maximum voltage supplied to the lamps caused by losses within the dimmer.
Instant Start Fluorescent Lamp: A fluorescent lamp designed to start using a high voltage without preheating the electrodes; this is also known as a cold-start lamp in some locations.
Insulator: A substance or material (such as rubber or glass) that will not permit the flow of electric current.
Integrated Dimmer: A multiple channel dimmer assembly that offers dimming system type features in a wall box footprint. May be used instead of ganged wall box dimmers or small dimming systems.
Integrating Photometer: A device for measuring the total output (luminous flux) of a source with a single measurement.
Intensity: The luminous flux per unit solid angle in a particular direction; may be expressed in candela or lumens per steradian.
Inverter: An electrical circuit that changes direct current (D.C.) to alternating current (A.C.) or vice-versa.
IP (Ingress Protection): The IEC (International Electrotechnical Commission) uses the term "Ingress Protection" or IP to define the environmental protection of an enclosure. This is described in IEC Standard 529. The IP classification system designates by means of a two digit number, the degree of protection against ingress of dust and moisture. The first digit defines the level of protection against solid objects, while the second digit defines the level of protection against moisture. The higher the digit, the greater is the level of protection.
J-Box: Jargon for junction box. A code-approved steel or plastic enclosure in which several wires come together for connection, such as the taps for fixtures.
J Box: An enclosure where conductors or wires are spliced or terminated.
Joist: A small structural beam, generally a member which directly supports a floor or roof.
Kelvin: A measurement of temperature. 1o F = 256o Kelvin. 1o C = 274o Kelvin. Used to measure color temperature.
Kilogram: A metric measure of mass equal to 2.2046 pounds.
Kilo: 1,000 in metric units.
L.E.D.: Light-Emitting Diode.
L.L.D.: The fractional remainder of lamp lumens lost, at rated operating conditions, due to lamp degradation. Mean lumen output divided by initial output.
L.V.D.: Protection feature in an emergency lighting unit in which the load is automatically disconnected when battery voltage drops to a critical point.
Lambertian Surface: A surface that emits, reflects or transmits light according to Lamberts cosine law; i.e. the surface has the same luminance regardless of the viewing angle.
Lamp: The actual source of light in a fixture. Some people refer to fluorescent lamps as "tubes" and incandescent lamps as "light bulbs.".
Lamp Efficacy: A metric used to compare light output to energy consumption. It is the ratio of lumens per watt.
Lamp Life: The number of burning hours at which 50% of any large group of installed lamps are still operational.
Lamp Lumen Depreciation Factor (LLD): The fractional remainder of lamp lumens lost, at rated operating conditions, due to lamp degradation. Mean lumen output divided by initial output.
Lampholder: The part of the light fixture that supplies the power to the lamp and also holds the lamp in place. Also called a socket. A lampholder bracket is the part of the fixture that holds the lampholder (socket) in place.
Lens: Transparent or translucent medium which alters the directional characteristics of light passing through it. Usually made of glass or plastic.
Lens: Transparent or translucent medium which alters the directional characteristics of light passing through it. Usually made of glass or plastic.
Lighting Economics: A cost evaluation of lighting systems. This evaluation will typically include initial costs, as well as all significant owning costs over time.
Lighting Specifier: A person (architect, engineer, lighting designer, owner, etc.) who specifies the lighting equipment for an installation.
Linear Response: Method of dimmer control where the measured light level is equal to the intensity control setting. For example, adjusting the control to 30% produces a measured light level of 30%.
Low Voltage Lamp: A lamp that provides both intensity and good color rendition. Lamp operates at 12V and requires the use of a transformer. Popular lamps are MR16 and PAR36.
Lumen (lm): A measurement of the light ouput of a lamp, or the SI unit of luminous flux. Photometrically, it represents the luminous output of a source with a uniform emittance of 1 candela over a unit solid angle of 1 steradian.
Luminaire: A complete lighting unit consisting of a lamp or lamps, the parts designed to distribute the light (housing), and any necessary starting components (ballast, socket, etc.).
Luminous Intensity: The luminous flux per unit solid angle in a particular direction; may be expressed in candela or lumens per staeradian.
Lux (LX): The metric unit of measurement of the illuminance of a surface. One lux is equal to one lumen per square meter.
Manual Control: A means of dimmer control where the intensity of each channel is individually adjusted.
Mounting Height: In a given application, the distance from the luminous area of the luminaire (typically the bottom) to the floor.
Multi-Level Switching: Applies to fixtures that have two or more ballasts, and thus have the ability to switch a multi-lamp fixture in such a way as to provide two or more levels of light; i.e., the ability to switch a 2-lamp unit so that only one lamp or both lamps are energized at a given time.
Nickel-Cadmium (Ni-Cad): A battery made with nickel and cadmium, abbreviated as Ni-Cad. Generally, the Ni-Cad battery is smaller and has a longer life expectancy than a lead battery.
Occupancy Sensor: Control device that acts as a light switch upon sensing that a person has entered a space. May be ultrasonic, infrared or other type.
Ohm: The standard unit of measurement for electrical resistance in a circuit.
Optics: A term referring to the components of a light fixture (such as reflectors, refractors, lenses, louvers, etc.); also the light-emitting or light-controlling performance of a fixture.
Overcurrent: A protective device for a branch circuit that prevents damage to the circuit due to a current surge or an overload; usually a fuse or a breaker.
Overlay: (1) Drawing or partial drawing which can be placed on top of others to add detail. For example, a reflected ceiling plan can be overlaid with the luminaire layout, air diffusers, sprinkler heads, etc., to create an image of all components on the ceiling. (2) Thin lens which is installed above another lens or louver in a fixture to create a desired effect (glare control, ultra violet filtering, radio frequency shielding, etc.).
Panelboard: An electrical distribution device which converts incoming electrical power into several smaller circuits and provides overload protection in the form of circuit breakers or fuses.
PAR Lamp: A Parabolic Aluminized Reflector Lamp. An incandescent or low voltage lamp used to redirect light from the filament in a manner resembling a parabolic reflector. Lamps are available with flood or spot distributions.
Pendant: Method of mounting fluorescent luminaires and track lighting. Mounting hardware consists of a stem and canopy set.
Performance Specification: A job specification in which the engineer has directed the electrical contractor to furnish and install lighting equipment that meets a detailed and precise set of performance parameters. These may include photometric, electrical, mechanical, and appearance aspects; a broader directive to the contractor as to the engineer's intent compared to a Prescriptive Specification.
Perimeter Lighting: Directs light at the edges of an area. Can be used to eliminate weak spots from general lighting.
Phase Control: The basic operating concept of electronic dimmers where lights are turned on for only a portion of each half of the electrical cycle.
Photocell: A Photovoltaic device used to control luminaires and dimmers in response to detected light levels. May provide either daylight compensation or daylight tracking.
Photometer: A device for measuring photometric quantities such as luminous intensity, luminance, illuminance and/or luminous flux.
Plenum: 1) Space between the structural ceiling and the finished ceiling. It is the service area concealing the housing part of a recessed fixture, as well as containing HVAC duct work, computer and telephone cables, electrical wiring, ceiling supports, plumbing, etc. 2) A compartment or chamber to which one or more air ducts are connected.
Power Surge: A sudden surge of high voltage on a power distribution circuit, usually caused by lightning or the switching on/off of heavy loads, especially motors.
Preliminary Drawing: Drawings created by the specifier in the early phase of a building design. These drawings are typically used for design concepts or feasibility studies.
Preset: Pre-defined intensity instructions for multiple channels on a dimmer control which may all be implemented simultaneously with a single activity (pressing one switch).
Prewired: A fixture which has electrical wires attached to it at the factory to make the installation of the fixture easier and faster.
Reflector: The part of a light fixture that shrouds the lamps and directs the light emitted from the lamp.
Refractor: A device used to redirect the light output from a source, primarily by bending the waves of light. (See LENS ).
Room Cavity Ratio (RCR): A ratio of room geometry used to quantify how light will interact with room surfaces. RCR = 5h (L+W)/(L*W).
Row Mounted: A continuous row of fixtures mounted end to end so that branch circuit wiring can be run through the channels. Row mounted fixtures are commonly seen in applications such as grocery stores or warehouses.
Scene: The resulting lighting effect of adjusting several channels of a light control system to desired intensity. May be implemented through either MANUAL CONTROL or PRESET selection.
SCR (Silicon Controlled Rectifier): A power electronic device often used in dimmers to regulate lamp power. Two SCR's are needed to build one dimmer.
Short Circuit: A circuit that has extremely low resistance causing the current to become very high. This is often caused by a current carrying wire touching a ground wire. Excessive current will damage a circuit or connected equipment; therefore protection must be included to prevent a short circuit.
Short Circuit Protection: A switch or fuse used to open the circuit when a short is detected.
Socket: Component that holds the lamp base and supplies electrical power.
Spacing Criteria: Spacing criteria (SC) determines uniformity by establishing spacing guidelines between rows and columns of fixtures. In order to ensure that there is not a dark area in between a group of 4 fixtures, the spacing criteria must not be exceeded. To arrive at the maximum recommended spacing of rows and columns, multiply the spacing criterion by the distance from the bottom of the fixture to the workplane height. The lower the number, the closer together the fixtures must be spaced.
Specification: The precise written detail of the building contract which accompanies the building plans. It normally includes all requirements of the general contractor and subcontractors to furnish and install the specified materials and equipment using prescribed methods and workmanship.
Specification Sheet (Spec sheet): (ALSO CALLED SUBMITTAL SHEET AND CUT SHEET)Data sheet that shows fixture dimensions, descriptions, options and photometrics. These sheets are submitted through the contractor, engineer and architect to obtain final approval on the specific equipment to be furnished.
Specifier: Usually an Electrical Engineer, Lighting Designer or Architect. This design professional specifies the type of lighting equipment, the layout of the lighting equipment, and the manufacturer of the lighting equipment.
Suspended Ceiling: A grid of connecting bars ("inverted tee" is the most common shape) suspended from the structural ceiling by wires. Acoustical tiles and light fixtures rest on these metal tees.
Tandem Wiring: Fixtures wired together in pairs so they share ballasts for switching capabilities.
Task Lighting: Supplements the ambient lighting when specific tasks require higher illumination.
Tempered Glass: A type of glass used for light fixtures which has a higher resistance to breakage than normal glass.
Template: A drawing tool, usually made of plastic, that contains cutouts of different shapes that can be traced onto a blueprint or drawing. Also describes a typical section of a lighting layout which can be transposed over all similar layouts.
Three-Way Switching: The ability to turn a circuit on or off from two separate locations, such as near 2 doors to the same room.
Time Delay: A fuse that has a built-in delay in the overload region. Time delay slows down the opening time in the overload region. Time-delay fuses are widely used for general purpose circuits and are especially suitable for loads with surge or starting currents.
Thermal Protector: A device that protects a ballast from overheating. The class P thermal protector is used in most ballasts today. This thermal protector is a bi-metal switch with the ability to open the circuit when the ballast becomes overheated, then close the circuit when the ballast cools down.
Track Lighting: Luminaires attached to a linear track system, used in accent lighting and other general lighting applications. The track can be recessed or suspended.
Transformer: A device designed to transfer energy from one circuit to another by electromagnetic induction. Transformers are typically used to increase (step up) or decrease (step down) the voltage from one circuit to another. The turns ratio, or number of windings on the primary and secondary sides of the transformer, will affect the change in voltage.
Tungsten Halogen: A tungsten filament incandescent lamp filled with halogen gas, with a lamp envelope made of quartz to withstand the high temperature. This lamp contains a certain proportion of halogens, namely iodine, chlorine, bromine, and fluorine that slows down the evaporation of the tungsten. Also commonly referred to as a quartz lamp.
Twin-Tube: Compact fluorescent lamp with two lamp tubes used in some Emergency Lighting, Downlighting, and Fluorescent products. The lamp life is about 10 times that of incandescent lamps and uses less power. Also referred to as PL or BIAX lamps.
U.L.: An independent organization whose responsibilities include rigorous testing of electrical products. When products pass these tests, they can be labeled (and advertised) as "UL listed." UL tests for product safety only..
U.V.: Light that is shorter in wavelength and higher in frequency than visible violet light (literally beyond the violet light)..
Ultra Violet (UV): Light that is shorter in wavelength and higher in frequency than visible violet light (literally beyond the violet light)..
Volt: The standard unit of measurement for electrical potential. It defines the force or pressure of electricity for the satisfactory operation of an electrical device..
Voltage: The potential difference between two points of an electrical circuit.
Wall Box Dimmer: A single channel dimmer with an integral means of manual control..
WallWash: Term used to describe lighting to illuminate vertical surfaces from ceiling to floor without shadows or hot spots. Fixtures used to accomplish this are called wallwashers..
Watt (W): The unit for measuring electrical power. It defines the energy consumed by an electrical device when it is in operation. The energy cost of operating an electrical device is determined by the watts it consumes times the hours of use. It is related to volts and amps by the formula: Volts x Amps = Watts..