A halide fixture is a versatile, powerful type of light. Its common uses range from illuminating sports arenas and big retail stores to nurturing the growth of plants in greenhouses. Halide fixtures are commonly employed among homeowners as floodlights and as light sources for aquariums, particularly those housing creatures that require bright conditions in order to thrive.
This type of light uses a chemical compound known as a halide, which is a halogen atom combined with a more electropositive element. Halide lamps use gas or vapor arcs as conductors, a feature that greatly increases their longevity. Incandescent light bulbs, on the other hand, rely on metal filaments that wear out more quickly and greatly reduce their life spans.
Although it's generally more expensive to use, a halide fixture will typically last about 20 times longer than incandescent bulbs. Their life span is comparable to that of other High Intensity Discharge (HID) lamps such as mercury and sodium vapor.
It's not uncommon for a halide fixture to give off an intense whitish glare. These lights are adaptable in terms of color temperature and can closely mimic daylight. This adaptability, sometimes referred to as "smart lighting," has led to their widespread use in live theater and film production. Their adaptability has also made them popular in home aquariums, especially those containing more light-sensitive creatures such as coral reef dwellers.
A halide fixture is often preferred because it can generate light much more efficiently than its incandescent, fluorescent and mercury vapor counterparts. For instance, a single 100-watt metal halide lamp can generate fives times as much light, measured in lumens per watt, as an ordinary 100-watt incandescent bulb. Halide lamps generate 65 to 115 lumens per watt which is much stronger than fluorescent lights (30 to 98 lumens per watt) and mercury vapor (35-58 lumens per watt). The halide fixture's power, however, comes with a requirement for special connections.
The powerful light generated by halide lamps also creates intense heat, meaning that the lamps can cause serious burns if handled improperly. Another concern is ultraviolet radiation, which can leak through broken seals and can, over time, cause sunburn-like irritation and damage eyesight. Many aquarium owners have complained of blurred vision after exposure to bright halide fixtures. Manufacturers recommend never looking directly into the bulbs, although only a broken bulb will allow UV rays to reach the eyes. They also advise giving the lights sufficient time to cool down before handling them.
The history of halide lighting dates back to 1912, when General Electric’s renowned engineer Charles Steinmetz patented an early form of the lamp. Lights using halide technology didn’t become available to the general public until the 1960s.