Lighting Terms

Below are the terms, definitions, and abbreviations that are commonly used on Good Earth Lighting website. Many definitions are based on information from the American Lighting Association.

Accent Lighting

Localized and directional lighting used to highlight, focus attention and dramatize. Accent Lighting fixtures include Spot Lights, Rope Light, and specialty products.

Ballast - Electronic

A Ballast that utilizes electronic components to transform current at high frequency to operate fluorescent or discharge lamps. As a rule, Electronic Ballasts are more energy efficent than Magnetic Ballasts.

Ballast - Magnetic

A Ballast that uses core and coil assembly to transform electrical current to start and operate fluorescent or HID lamps.

Ballast Factor

The measured ability of a particular ballast to produce light from the lamps it powers. Ballast Factor is derived by dividing the lumen output of a particular lamp/ballast combination by the rated lumen output of the same lamp on a reference ballast. A Ballast Factor of 1.0 equals 100% of the lamps rated lumen output.


Typically used in dining rooms and in the foyer. Providing general lighting, a chandelier can be a focal point of style and beauty for a room. Chandeliers are jewelry to the home decorator.

Compact Fluorescent

Compact Fluorescent lamps “CFL” are energy efficent , long lasting light bulbs that are useful for replacing incandescent lamps in small fixtures. The lamp life is about ten times longer and use about one-fifth of the energy of regular light bulbs.

Circle E Ballast

Indicates special EPACT compliant version of ballast. Check the laws and codes for specific applications.

Color Rendering Index

CRI-indicates how true to color lighted objects appear. CRI measures light sources on a scale of 0 to 100. A higher number means more accurate color rendering. Sunlight is the benchmark for CRI at 100. Most residential applications use lamps with a CRI of at least 80.

Color Temperature or Chromaticity

The appearance of white light, in terms of warmth or coolness. The color temperature is measured in Kelvin or "k." The higher the color temperature, the visually cooler or bluer the light appears. Typical indoor residential lighting requires light in the 2700K – 3500K range. Commercial, utility, and outdoor lighting is generally specified in a range between 3500K – 5000K range.

Damp Location

A UL Listing specification for a lighting fixture: An exterior or interior location that is normally or periodically subject to condensation of moisture in, on, or adjacent to, electrical equipment, and includes partially protected locations. Damp location fixtures can be installed in an application that is subject to periodic dampness but not in direct contact with rain or any other water source.


Light control device that spreads light by scattering it, such as opal glass, etched glass, plastic, fabric, and paper shades.


A control device that varies the output of the light source by reducing the voltage or current to the lamp. Dimmers vary according to the type of lamp/fixture. Be sure to check if your fixture is dimmable and what dimmer is compatible with your fixture.


A specialized power supply that utilizes electronic components to transform current at high frequency to operate LED devices. LED devices require a specific Driver that is designed to supply power for the load and LED type on that circuit.


A Safety and Performance Compliance agency that tests products against several recognized standards. ETL for lighting compliance uses UL testing standards to approve product Listings for safety.

Etched Glass

Glass treated by an acid bath, producing a satiny, frosted surface or design.


Distribute a widespread pattern of intense light generally used in outdoor settings for security.

Flush Mount

The flush mount fixtures attach directly to the ceiling with no gap between the fixture and the ceiling.


The measurement of the amount of light reaching a specific surface. Footcandles are measured in lumens per square foot.

Halogen Lamp

An Incandescent lamp with halogen gas fill and a quartz glass capsule. It operates at higher internal temperatures, producing more lumens per watt and brighter light than ordinary incandescent.

HID (High Intensity Discharge) Lamp

A lamp that uses compressed gasses including Mercury, Metal Halide, and Sodium types. HID lamps requre a specific ballast to power each lamp type and wattage.


A manufactured light source, including a bulb, base, and internal light-producing structure. AKA “light bulb” – a lamp gets its brightness from LED, Fluorescent, HID and Incandescent sources.

Lamp Efficacy

Different lamp types have different abilities to convert electrical power into visible light. The quantity of light emitted (lumens) is divided by the input power (watts) to determine the lamps efficacy. This is expressed as lumens per watt LPW.


Light Emitting Diode. A small, solid state device that emits visible light when electrical current is applied. LED require a Driver or power supply circuit that converts houshold power (120V) into low voltage.

Lamp Life

How long on average a bulb is estimated to last. The number of hours on average it takes 50% of a group of lamps to fail under controlled test conditions. Also known as “half-life” – if you have 100 test lamps and 50 of them burn out in 10,000 hours, then your Lamp Life is 10,000 hours. 10,000 hours is the minimum Lamp Life for Energy Star Compact Fluorescent Lamps used by Good Earth Lighting.


Lumens per watt measure of energy efficiency. Fluorescent lamps are very energy efficient and emit up to 100 lumens per watt.


The amount of visible light from a Lamp (light bulb). A higher number means brighter light. A typical 60W incandescent lamp produces 800 Lumens.


Generally are suspended on cords or stems from the ceiling over kitchen islands, dinette tables, or other work areas such as home offices. They provide task or accent lighting and can be fitted with decorative shades of metal, glass, fabric, and other materials.

Octron Ballast

A ballast designed to operate 1" diameter, T8 fluorescent R.S. lamps. It is not compatible with T12 or preheat lamps.

Outdoor Lighting

Used to illuminatethe area around the home or outdoor living space. Generally refers to any hardwired, low-voltage or solar powered lighting that is used for illuminating outdoor areas. They can enhance your home, patio and landscape.

Opal Glass

White, translucent glass produced by adding ingredients to clear glass and used for diffusing light.

Pendant Lights

Fixtures suspended from the ceiling on a cable, chain, or stem that have a single large decorative shade. Common applications are in the living room, eat-in kitchen and dining room.

Portable Lamps

A table lamp or floor lamp that can be easily moved and plugs into an electrical outlet.

Power Factor

The ratio of power (watts) to volt-amps of the ballast. The power factor ratio may be used to determine how efficiently total input power is being used. A High PF Ballast is more efficient , turning most of the input power into usable current for the lamp that it powers.

Security Lighting

A functional solution to illuminate a landscape, driveway or parking area for convenience and as a deterrent to any criminal activities for homeowners’ safety. Most Security Lighting is switched on by a sensor when it is dark or when it senses motion (or both).


Wall mounted fixture with a incorporated diffuser design or derived from the form of chandelier, often with exposed or decorative light sources.


A component that covers the light bulb on a light fixture to diffuse the light it emits. Also, see Diffuser.

Shop Lighting

Usually refers to garage lighting. Ceiling-mounted fluorescent light fixtures to provide ambient lighting or installed above your workbench to provide task lighting.

Under Cabinet Lighting

Lighting fixtures installed under a cabinet, shelf, or similar surface in order to produce localized lighting on a work surface below. Some Under Cabinet Lights can be installed inside cabinets to illumniate decorative dishes or curio items.


Underwriters’ Laboratories. A non-profit Safety Compliance organization that works with the National Electrical Code to develop standards for electrical devices, wiring, and lighting fixtures. They test fixtures and materials for compliance with the standards and List fixtures for various applications, such as Wet Location.

Utility Lighting

Lighting fixtures used for providing ambient and task lighting in areas such as laundry rooms, closets, or utility rooms. Utility lighting is generally not overly decorative and provides high light output for the size of the fixture.

Vanity Lights

A fixture used over a bathroom mirror or vanity for grooming or to apply make- up. It is ideally a long or mulitiple lamped, well diffused source of light.


Unit of electrical force or pressure. Household voltage in United States, normally 120 volts, varies between 110-125 volts.


A measure of electrical power expressed in watts.

Wet Location

A UL Listing specification for a lighting fixture: An interior or exterior location where water or other liquid can drip, splash, or flow on or against electrical equipment. Wet Location fixtures can be installed in bathroom showers and in outdoor applications where they come in direct contact with rain or water from sprinklers.


A type of incandescent lamp, principally characterized by the use of Xenon gas inside. Xenon lamps are commonly used for strip lights, under-cabinet lighting, and recessed display lights.