Glossary of Lighting Terms

Absorption of Light occurs when a ray of light strikes a surface and the energy from the light is transferred to the surface material.

Accent Lighting is lighting directed at a particular object in order to focus attention on it.

ADA- The Americans with Disabilities Act sets regulations that assert limits and standards that contractors must meet and comply with when installing light fixtures in public buildings. If a fixture is more than 80 inches above the floor, then it is automatically ADA compliant. Wall sconces must be placed under 80 inches and to be considered ADA compliant, it cannot extend more than 4 inches away from the wall.

Ambient Light is light that exists in a scene and is also referred to as “natural or existing light”.

Arm is a decorative-shaped tube or casting that is used to support a socket. An arm usually has socket wires running through it.

Backplate is the part of a fixture that mounts to a wall or vertical surface.

Ballast is a device that provides the proper starting and operating electrical condition to power one or more fluorescent or HID lamps.

Canopy is the decorative plate that attaches to the ceiling to cover the junction box.

Chandelier is a multi-arm, decorative, often ornate ceiling light fixture that holds a number of bulbs.

Collection is a group of matching fixtures and/or lamps that together can bring a unified look to a home or room.

Diffuser is a covering or shade over a light or lamp that generally softens or scatters the light and is usually used to eliminate hot spots and glare.

Dimmer is a control that regulates light levels.

ETL (Intertek) is an independent testing company.

Extension is the measurement from the wall to the farthest point away from the wall on a fixture.

Finial is a small finishing ornament at the crown or bottom of a fixture.

Fixture is a light that is permanently attached or wired directly into a junction box. Chandeliers, bath lights and wall sconces are examples of “fixtures”.

Floating Flush mount is fixture that is not actually flush to the ceiling. The glass is a few inches from the ceiling...closer than a semi flush mount.

Flush Mount is a fixture attached directly to the ceiling with no gap between the light and ceiling.

Halogen lamp is an incandescent lamp containing halogen gas.

Harp is the wire support that attaches at the socket and supports the shade at the top of the lamp.

H.C.W.O. (Height to Center of Wall Opening) is the measurement from the mounting location of the fixture to the top of the fixture.

Incandescent Lamp is the traditional type of light bulb that produces light through electricity causing a filament to glow.

Inverted Pendant is an ornamental hanging fixture without multiple arms where the glass or diffuser opening is facing the ceiling.

Lamp is the term used in the lighting industry that refers to a light bulb.

Lumen is a measure of the total amount of visible light emitted by a source.

Pendant is an ornamental hanging fixture without multiple arms where the glass or diffuser opening faces down.

Portable – a luminaire that is simply plugged into an outlet and can easily be picked up and moved. Table and floor lamps are examples of portables.

Proposition 65 is part of the California Safe Drinking Water and Toxic Enforcement Act of 1986.

Sconce is a decorative lighting fixture with a flat side to be hung on a wall.

Semi Flush mount is fixture that attaches to the ceiling canopy with a stem or part that creates a gap between the fixture and ceiling.

Switches are controls for electrical devices.

Swivel allows a fixture to mount on a sloped ceiling and hang straight.

Task lighting is illumination designed for a work surface to provide good light, free of shadows and glare.

Timers are control devices to activate luminaries at set timed intervals.

Torchiere is a tall floor lamp with a bowl shaped glass that diffuses the light or directs it upward.

Transformer is a device which can raise or lower electrical voltage, generally used for low voltage lights.

UL (Underwriters Laboratory) is an independent testing company.

Voltage is a measurement of the pressure of electricity going through a wire. Most households in North America are 110-120.

Watt is a unit of electrical power.