Frequently Used Terms
Term Definition
Ballast Provides the proper starting voltage to the lamp and regulates the lamp’s starting and operating current.
Capacitor Used in some HID systems for power factor improvement (increased efficiency) and lamp current limiting.
CFL Compact Fluorescent. More efficient than Mercury Vapor but less efficient than Metal Halide. Good color rendering but poor cold temperature operation.
Color Rendering An evaluation of how colors appear under a given light source.
Color Temperature Lamp light color expressed in Kelvin.
Diffuser Scatters the light emitted from the lamp to increase light coverage area and to reduce glare.
Dusk-to-Dawn® Typically describes the operation of a light fixture that turns on automatically at dusk and turns off automatically at dawn.
Efficacy A measure of efficiency expressed in lumens per watt.
H.I.D. High Intensity Discharge
HPS High Pressure Sodium. The highest efficiency fixture Heath/Zenith offers. Produces an amber/yellowish light color.
Lumen Maintenance The gradual reduction in the amount of light emitted by a light source over time with normal use.
Lumens A measure of light output.
Medium Base Bulb Smaller size lamp base used on low to medium wattage HID lamps and incandescent lamps.
Mercury Vapor More efficient than Incandescent but less efficient than CFL. Its blue/white light color is considered an average color.
Metal Halide More efficient than CFL. White light with very good color rendering.
Mogul Base Bulb Larger size lamp base used only on higher wattage HID lamps.
Operating Position Recommended operating position of lamp in fixture (e.g. base up or base down) in order to achieve targeted life and performance.
Photo Control Device incorporating a photocell (light sensitive resistor) and bimetal switch used for Dusk-to-Dawn® operation of a light fixture.
Re-Strike Time The amount of time required for an HID lamp to restart after reaching normal operating temperature and being shut off - typically around 10 minutes.
Watts A measure of electrical power - i.e. energy consumption.