ABSTRACT
The total light from a light source is measured in lumens. Lamps are labeled with measured lumen ratings and efficiency ratings. In the English system, the quantity of light that falls on a work surface is measured in footcandles. In the SI system, the lux is the measure of illuminance. Color temperature describes the actual appearance of the light being produced by a lamp, but it provides no indication of how the lamp will affect the color appearance of objects. Color rendition describes the effect a light source has on the appearance of colored objects. The color rendering capability of a lamp is measured as the Color Rendering Index (CRI). All fluorescent ballasts perform two functions: they provide the right voltage to start the arc discharge, and they regulate the lamp current to stabilize light output. Ballast efficiency is regulated by the Federal Appliance Standard that prohibits the manufacture of ballasts that do not meet a minimum Ballast Efficacy Factor.
