High/Low-Bay Applications: Fluorescent or Metal Halide?

A good white paper that details the advantages and disadvantages between Fluorescent and Metal Halide systems. Induction lighting gets a mention.

The original document can be found here: http://www.aboutlightingcontrols.org/education/papers/high-low-bay.shtml

Induction lighting

Some manufacturers have recently introduced induction lighting fixtures as a replacement for HID fixtures in high-ceiling applications. Like fluorescent, induction lighting offers the benefits of instant on and instant re-strike, ability to be used with occupancy sensors, lamp-to-lamp color consistency, good lumen maintenance, and negligible color shift. Primary advantages include compact fixture size, up to 100,000-hour rated lamp life, and retained performance in extremely cold conditions.

An induction system is similar to a fluorescent system in that mercury in a gas fill inside the bulb is excited, emitting UV radiation that in turn is converted into visible white light by the phosphor coating on the bulb. Like fluorescent, the phosphor coating determines the color qualities of the light. Fluorescent lamps use electrodes to strike the arc and initiate the flow of current through the lamp, which excites the gas fill. Each time voltage is supplied by the ballast and the arc is struck, the electrodes degrade a little, eventually causing the lamp to fail. Induction lamps do not use electrodes. Instead of a ballast, the system uses a high-frequency generator with a power coupler. The generator produces a radio frequency magnetic field to excite gas fill. With no electrodes, the lamp lasts longer. Induction lamps, in fact, last up to 100,000 hours, with the lamp producing 70% of its light output at 60,000 hours. In other words, their rated life is 5-13 times longer than metal halide (7,500 to 20,000 hours at 10 hours/start) and about seven times longer than T12HO fluorescent (at 10 hours/start).

Long life with subsequent maintenance and lamp replacement savings, combined with high system efficiency, result in life-cycle cost savings for the owner.

Induction lamps are ideally suited for high-ceiling applications where the lamps are difficult, costly or hazardous to access. They are also ideally suited for such applications where the advantages of fluorescent lighting are sought but a light source is needed that can start and operate efficiently in extremely cold temperatures. As a result, induction lighting is a suitable for a wide range of applications, including not only warehouses, industrial buildings, cafeterias, gymnasiums, etc., but also signage, tunnels, bridges, roadways, outdoor area and security fixtures, parking garages, public spaces, and freezer and cold storage lighting.

Induction lighting poses several disadvantages. These lamps cannot be dimmed. Induction lighting cannot retrofit existing HID fixtures without a dedicated retrofit kit. In addition, an induction system can cost up to 4+ times more than an HID system.