Lighting and Electrical Glossary

Published By: Shades Of Light

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Last Updated: May 23, 2017

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Looking for the name of "that" piece or part on a light fixture? Or maybe you’re trying to explain an idea to your electrician. Here's a list of definitions for those parts, pieces and terms to help.

Terms used in lighting

  • AC: Alternating current: An electrical current that reverses its direction at regular intervals
  • Accent lighting: Lighting that focuses on a specific object or architectural feature
  • Ambient lighting: General lighting in a room
  • Amp: Measure of rate of electrical flow in a circuit
  • Backplate: Flat plate behind wall sconce to cover electrical box
  • Baffle: Waffle device used to reduce glare
  • Ballast: Device used to control the current and prevent overheating in a discharge lamp
  • Barn doors: Hinged shutters used to precisely shape the beam of a lamp
  • Bobeche: Decorative crystal, metal, wood, etc. “bowl” used on chandeliers and sconces, often pierced to hold crystals (originally used to catch wax dripping from candles)
  • Breaker box: Metal box with fuses or circuit breakers that breaks down electrical service into smaller circuits
  • Bus bar: Fuse box, breaker box
  • BX or flexible metal conduit: Bendable tubing that holds electrical lines
  • Candlecover: Plastic, metal, or cardboard sleeve that simulates the look of a wax candle (to conceal a socket)
  • Candela: Unit of light intensity (SI), roughly equivalent to 12.57 lumens
  • Candlepower: Luminous intensity of a light source measured in candela
  • Canopy: Decorative plate that goes flush to the ceiling on a chandelier or ceiling light that conceals electrical box
  • Chimney: Open-ended glass surround used on an oil lamp to hold lampshade
  • Circuit: Path of electrical flow (wiring)
  • Circuit breaker: Switch that interrupts electricity in case of a short or overload
  • Check ring: Metal disk that holds candlecover or neck on a light fixture
  • Clip adapter: Metal bulb clip that attaches to a lampshade converting it to a shade that clips onto the bulb
  • Collar: Threaded ring that holds the canopy to the ceiling on a chandelier
  • Color rendition index: A measure of the effect of a particular kind of light bulb on a colored surface (the larger the number, the truer to the color in real sunlight; measured between 1 and 100)
  • Common: Dark-colored screw on an electrical switch
  • Conductor: Wire that carries electricity
  • Conduit: Rigid or flexible tubing that holds electrical wires inside
  • Contacts: Connection point for electrical wires
  • Continuity Tester: Test device for electrical circuit
  • Cord switch: On-off switch for a portable lamp that attaches along the cord
  • Current:Flow of electricity through a wire, measured in amps
  • DC (direct current): Electrical current that flows in only one direction, not a complete circuit
  • Diffuser: Translucent “shield” designed to reduce glare and filter light more evenly
  • Dimmer: Switch that allows you to vary the intensity of a light fixture
  • Discharge lamp: Light bulb which incorporates an electronic discharge through a gas or vapor
  • Duplex receptacle: Outlet with 2 plug-in connections
  • Efficacy: Lumens per watt measure of the efficiency of a light source
  • Electrical box: Box in the wall where electrical connections are made to fixtures and that supports fixtures
  • Electric meter: device that measures amount of electricity consumed
  • Electronic transformer:
  • Faceplate: Switch box or outlet cover plate
  • Filament: Thin tungsten wire that emits light when heated by an electrical current
  • Finial: Decorative item with threaded base used to secure a lampshade to a harp and “finish” the look of a table or floor lamp
  • Fish tape: Extending metal tape with a hook on the end used to pull wires through a wall
  • Fitter: Decorative rim that holds glass shades on place on a light fixture
  • Fixture: Any decorative electrical item that permanently affixes to a wall or ceiling
  • Flush mount: Light fixture that hangs flush on the ceiling
  • Foot switch: Device for turning a floor lamp on and off that sits on the floor and is joined to the cord
  • Framing projector: device that allows you to accurately control the size of the light beam
  • Fuse: Screw-in, plug-in, or snap-in device that interrupts electricity in case of a short or overload
  • Ganging: 2 or more electrical lines ending in the same switch box or receptacle
  • Ground wire: Wire (that carries no current) that runs from the fixture to metal attached to nonmetal material to ground the current in case of a short (Ground wire is usually bare copper or green).
  • GFI: Ground-fault interrupter: A sensing device that shuts down the electricity in the case of a shock hazard
  • Harp: Metal “U” that supports lampshade over bulb and lamp base
  • Harp holder: Metal “U” that connects harp to lamp base
  • Hot wire (live wire): Wire that carries the current to a receptacle and fixture (usually black)
  • Hurricane: Decorative glass surround for candle-like sockets
  • Illuminance: Amount of light that falls on a surface (measured in lumens per square foot)
  • Indirect lighting: Lighting that is reflected off a wall, ceiling, shade, etc.
  • Insulation: Nonconductive coating that protects electrical wires
  • Junction box: Connection point for wires from fixture to fixture and switch box to fixture
  • Kelvin (color temperature): Measure of redness or blueness of a light source (the higher the number, the warmer the color)
  • Kilowatt: 1000 watts (measure of electrical consumption)
  • Knockouts: Tabs that can be removed from electrical box or fixture to make wiring connections
  • Lamp: Technical name for light bulb
  • Loop: Threaded U-joint that attaches chain to the canopy on a chandelier
  • Locknut: Threaded nut used to tighten parts inside a light fixture
  • Louvers: Parallel slats on a lighting fixture used to prevent glare and direct light
  • Low-voltage: Reduction of regular household current (120 volts) to a lower voltage (usually 12-volt) using a transformer
  • Lumen (measured in footcandles): Measure of amount of light emitted (one lumen is the amount of light from one candle one foot away)
  • Magnetic transformer:
  • Medium base: Socket size for a regular household bulb
  • NEC code: National Fire Protection Association codes for wiring
  • Neck: Brass or decorative rod used to add space between a lamp base and the socket
  • Neutral wire: Wire that carries current from receptacle or fixture back to the fuse box to complete the circuit (usually white)
  • Outlet: Point at which electrical wire attach to fixtures, receptacles, or switches
  • Pendant: Light fixture that hangs from the ceiling
  • Polarized plug: Plug on portable lighting item with different shaped prongs to ensure that the hot and neutral wires can’t be reversed
  • Raceway: Exterior channel that allows wires to be run on the surface of a wall or ceiling
  • Rated life of bulb: Number of hours at which 50% of the bulbs will fail under standard conditions
  • Receptacle: Outlet that supplies power for plug-in electrical items
  • Reflector: Mirrored or polished surface designed to project light in a specific direction
  • Riser: Threaded brass rod that screws into the top of a harp to raise the lampshade
  • Romex cable: Romex is a common brand name for Nonmetallic (i.e. plastic) sheathing for wiring which carries hot, neutral and ground wires, both one and two circuit. It is used in dry, protected areas like stud walls, not underground. A similar cable, commonly called UF, has a heavier plastic sheathing and is suitable for underground uses, like outdoor lighting.
  • Sconce: Light fixture that hangs on the wall
  • Semi-flush mount: Light fixture that hangs down from the ceiling less than 2’
  • Service panel: Main fuse box where electrical service enters the home
  • Set screw: Knurled-edge screw used to hold a glass shade tight in the fitter
  • Short: Spark resulting from neutral and hot wires touching each other causing a blown fuse or circuit breaker flipping to off
  • Silver crown bulb: Bulb with silver coating on the end to reduce glare
  • Single pole: Light switch in the wall where you can only cut on & off the light from that one location
  • Socket: Electrical component that connects to 2 electrical wires and has threads for light bulb to screw into
  • Socket reducer: Screw-in socket that attaches to another socket to reduce the size of the bulb base
  • Spider: Three top horizontal rods of a lampshade frame
  • Splice: Connection made by joining 2 or more wires
  • SPT2 wire: Technical term for lamp wiring cord
  • Starter: Magnetic coil that strikes an arc between electrodes when a fluorescent bulb receives electricity
  • Stripping: Removing insulation from electrical wires to allow a connection between wires
  • Three-way bulb: Bulb with 2 different wattage filaments, allowing you to turn on each separately or both together
  • Three-way switch: A light control switch that allows you to turn the fixture on and off from 2 different locations
  • Transformer: Electrical device that changes the amount of voltage in a wiring line
  • Magnetic Transformer: Larger & heavier transformer using copper around a steel core to step down elctricity from 120 volts to 12 volts. Requires special magnetic dimmer.
  • Electronic Transformer: Compact & lightweight and more efficient than magnetic transformer. Requires electronic low-voltage dimmer.
  • Turn knob: Brass or plastic screw-on knob used to switch a portable lamp on and off
  • Underwriters knot: A special kind of knot in 2 electrical wires to secure the wires from pulling out from the socket
  • UL: United Laboratories testing organization that issues guidelines and provides testing to ensure wiring safety
  • Vase cap: Brass or wood cap to cover the opening in the top of a vase when converting it to a lamp
  • Volt: Measure of electrical pressure in a circuit
  • Voltage drop: Loss of electrical current on long wiring runs
  • Washer: Open round disc in the center of the top horizontal rods of a lampshade
  • Watt: Measure of electrical power being used on a circuit (volts x amps = watts)
  • Wire nut: plastic-enclosed coil used to join the ends of 2 or more electrical wires
  • Zip cord: Electrical cord with 2 wires joined with grooved insulation between them

Lighting Techniques

  • Downlighting: Light filtering downward from above casting shadows on the floor in a moonlight effect
  • Grazing: Positioning of a light source in a vertical direction close to a surface to highlight surface texture
  • Silhouetting: Light from behind to create an outlined effect of an item
  • Spotlighting: Highly focused beam of light
  • Task Lighting: Lighting that focuses light on areas where tasks are done (reading, make-up, cooking, etc.)
  • Uplighting: Technique of lighting an item from below, creating shadows above
  • Wall washing: Light up entire wall usually from at least 3’ away

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