systems, because usually the dominant harmonic current is the third harmonic. The third harmonic currents add in the neutral wire of the electrical system and in cases of high THD one can have a situation where the current flowing in the neutral wire exceeds the rating of the wire, causing overheating.

troffer: A long, recessed lighting unit usually installed with the opening flush with the ceiling. (ANSI and IES, 2010)

vacuum thermal evaporation: A method of deposition in which a material is heated in vacuum, evaporating from the source and then condensing on the substrate.

valence band: See band gap.

visible spectrum: The band of electromagnetic radiation that can be detected by the human eye, encompassing wavelengths between 380 nm (violet) and 750 nm (red).

warm white: Light described as “warm” has a coordinated color temperature (CCT) at the low end of the CCT spectrum. It is usually perceived as slightly yellow.


ANSI (American National Standards Institute) and IES (Illuminating Engineering Society). 2010. Nomenclature and Definitions for Illuminating Engineering. New York: ANSI and IES.

California Energy Commission. 2002. Energy Quest. Glossary of Energy Terms. Available at Updated May 20, 2002.

Industrial Fiber Optics. 2004. Fiber Optic Lab Manual: Fifth Edition. Tempe, Ariz.: Industrial Fiber Optics, Inc.

Philips Color Kinetics. 2010. LED Lighting Explained: Understanding LED Sources, Fixtures, Applications, and Opportunities. Burlington, Mass.: Philips Solid-State Lighting Solutions, Inc.

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