Edison Base

When referring to a threaded screw base it is abbreviated as "E". Most of the time this refers to a standard medium base technically called an E26 base.


The measurement of how efficiently a light source converts power (watts) into light. The efficacy of a light source is expressed in lumens per watt (LPW). See Lumens Per Watt.


The shortened version of Energy Independence and Security Act. See Legislation.


A piece of conductive metal, often tungsten, used to conduct electrons or in other words permit electricity to flow through a gas fill. Electrodes are used in all discharge bulbs other than induction bulbs. They are classified as cathodes and anodes.

Electrodeless Bulb

  • A bulb technology that operates without electrodes. The most common present day version of this technology is known as an induction bulb.
  • Induction Bulb

    Induction bulbs use radio waves for the excitation of its internal gases and mercury. They have a significantly increased lifespan over HID bulbs for example of 100,000 hours or more. This lifespan is simply theoretical and actually could be much longer. However, while a bulb may have a very long lifespan, any bulb that relies on intermediary circuit components may have a factor other than the bulb itself that causes the bulb to become inoperative. This technology is able to generate high lumen outputs and is considered to be an HID substitute of sorts. Its luminous efficacy is not significantly superior if at all to that of metal halide bulbs.

Electromagnetic Ballast

A simple type of low frequency ballast that operates using a core and coil design to start both fluorescent bulbs and high intensity discharge bulbs.

See Ballast.

Electromagnetic Radiation

Energy such as light, radio waves, gamma rays, and X-rays emitted in the form of electromagnetic waves in which the electric and magnetic fields vary simultaneously.

Electromagnetic Spectrum

The full spectrum of radiation (light) ranging from cosmic rays to broadcast bandwidths.



One of the four fundamental forces of nature. Manifestations of the electromagnetic force include electric fields, magnetic fields, and light.


A particle that carries a negative charge and serves as the primary carrier of electricity.

Electronic Ballast

See Ballast.

Enclosed Rated

See Enclosed Rating.

End of Life

Abbreviated as EOL.

Energy Independence and Security Act

Abbreviated EISA.

See Legislation.

Energy Policy Act

Abbreviated as "EPACT". See Legislation.

Energy Star

  • Program developed in 1992 as a joint effort between the Environmental Protection Agency (EPA) and the Department of Energy (DOE). Served to indirectly establish additional regulation of product standards by offering voluntary participation to interested manufacturers.
  • The Energy Star program sees the consumer market as its largest consumer of covered products and thus tends to be of greater importance to that market as opposed to the commercial market.
  • Energy Star does no internal testing and thus contracts all testing out to private laboratories.


A name for the outer shell or "container" of a light bulb. Most commonly it is glass but can be made of other materials. The term envelope is generally used when speaking of a solid simple shaped outer shell of a bulb such as a cylindrical, spherical, egg shape or the like. So, for example it would not be accurate to refer to the outer glass of a helix shaped bulb as an envelope.


The acronym for Energy Policy Act.

See Legislation.


Mark issued by Intertek Laboratories to certify the compliance of a tested item with an applicable standard such one written by Underwriter's Laboratories or American National Standards Institute. This listing is essentially the same as an Underwriter's Laboratories certification.



Excessive Neutral Current

"Current overload created in the neutral wire of 4-wire, three phase Wye systems by load unbalance or 'third harmonic'." - Advance Ballast Glossary