Arc Lights

Arc Lights also known as HID Lights

An arc light is a High Intensity Discharge (HID) light that uses an arc between two electrodes in a gas-filled tube which causes a metallic vapor to produce radiant energy. The electrodes are in close proximity within a sealed gas filled tub and is under pressure. The arc generates extremely high temperatures, causing metallic elements within the gas atmosphere to vaporize and release large amounts of visible radiant energy.

The HID light bulb does not receive direct line voltage like a filament lamp. A ballast is used much the same as with fluorescent lighting. The ballast is specifically designed for the type of arc light bulb being used. HID lamps require a warm-up period to achieve full light output and any interruption disrupts the arc causing another delay to achieve full luminosity.

Mercury Vapor

The mercury arc produces a bluish light that renders colors poorly. Therefore, most mercury vapor lamps have a phosphor coating that alters the color temperature and improves color rendering to some extent. Most street lights once used Mercury vapor bulbs but have since been replaced by low pressure sodium lighting.

• Mercury vapor lamps provide about 50 lumens per watt, but ballast loss can reduce the system efficacy to about 30 lumens per watt

Metal Halide

Metal Halide bulbs use chemical compounds known as “halides” that produce light in most regions of the spectrum. The bulb offers both energy efficiency with excellent color rendition.

High Pressure Sodium

This bulb is designed with a greater focus on energy efficiency rather than color rendition. Mercury and sodium vapors in the ceramic arc tube produce an bright orange tinted light with extremely high LPW performance and longer service life.

Low Pressure Sodium

This bulb type is even more energy efficient and survives longer than the HPS light, however, color rendition is further sacrificed to a deeper orange colored light.