Ideal Light Source

A perfect light source for a particular application. The most common light source referred to as an ideal light source is the noonday sun.

Illuminating Engineering Society

  • "Group of professional lighting engineers and designers." - Advance Ballast Glossary
  • A professional organization that establishes a number of standards and recommended practices in the field of lighting design.

Incandescent Bulb

A light source which relies upon a filament made of tungsten wire as its method of generating both heat and light. Electrical current is conducted through the tungsten filament which is heated by this process. The emission of light which results from the filament's high temperature is called "incandescence".

Industrial Reflector

See Fixture.

Infrared Spectrum

  • Abbreviated as "IR". It was originally discovered in 1800 by Sir William Herschel as a result of his observations of the effects that an unknown type of invisible radiation had on a thermometer. "Thermal infrared, which corresponds to wavelengths longer than about 5 microns [5,000 nm] is a direct measure of temperature."* In essence everything emits infrared radiation (including ice cubes).* Infrared radiation is often used as a heat source but it is worth noting that any wavelength including, but not limited to those in the visible spectrum will heat any object that will absorb it.
  • Different organizations define the ranges of infrared wavelengths in different ways.
    • General Electric defines infrared radiation as the range of wavelengths from 780 to 1106 nanometers. This is a practical definition for the purposes of the lighting industry.
    • The International Commission on Illumination (CIE) divides the IR band as follows:
      700-1400 nm
      1400-3000 nm
      3000 nm-1 mm


No longer functioning as intended, specifically to the point that it is either no longer functioning or must be removed from operation. This means that a product could still be in active service yet could be deemed inoperative because, for example it is no longer safe to continue to operate it.

Input Voltage

The voltage supplied to an electrical system such as a light bulb, driver, ballast or transformer. It is not used to describe the voltage being supplied to any component that receives power from a driver, ballast or transformer that is installed within a lighting system.

Institute of Electrical and Electronics Engineers

  • Abbreviated IEEE.
  • "Organization of engineers that establishes standards for electrical and electronics industries." - Advance Ballast Glossary


"necessary to make a whole complete; essential or funda-mental." - Google Definitions

Integral Ballast

A ballast that is built into (integrated into) a light source such as a LED or compact fluorescent bulb.

Integral Circuit

"Circuit of transistors, resistors and capacitors constructed on a single semi-conductor chip, all interconnected to perform a given function." - Advance Ballast Glossary

Internal Fuse

"A device that disconnects [a] ballast to prevent damage in the power distribution system." - Advance Ballast Glossary

International Commission on Illumination

The English name for Commission internationale de l'éclairage. Pursuant to the French name it is abbreviated as CIE. It was established in and replaced the Commission Internationale de Photométrie in 1913. It is based in Vienna, Austria. It is accepted as the international authority on light, illumination and color.

IP Fitting

IP stands for Iron Pipe. A method of mounting a socket which uses a threaded female opening on the bottom of a socket that threads onto a piece of threaded metal tubing. Lighting IP fittings are almost always 1/8". This is in no way related to Ingress Protection.


IP Rating

See Ingress Protection.

Iron Pipe

Abbreviated as IP. Refers to a thread standard for threaded pipe. See IP Fitting