The differences between halogen, and metal halide lamps are numerous, and quite significant. Both use unique technologies, and have tasks they perform better, or more efficiently. This article will not only explore what each technology is, but also the differences, possible advantages, and disadvantages of both types.

Halogen lamps are classified as an incandescent, and are similar to most typical household light bulbs. As with conventional incandescent bulbs, halogen lamps have a tungsten filament inside of a bulb. This however, is where the similarities end. Even the bulb portion is typically made from quarts instead of conventional glass, to withstand higher temperatures.

The gas used to fill the bulbs is what gives these lamps their name. Halogen is a group of five elements on the periodic table, however, today only bromine, and iodine are used in gas form. The use of this gas creates what is known as a halogen cycle. This basically means, while heating up the filament partially vaporizes, but then redeposits back on the filament. This will happen repeatedly, while supplied with power. A typical halogen cycle is virtually undetectable to the user. However, because of this process, the bulbs can last longer, reach higher temperatures, and achieve a much brighter white output.

Halogen lamps do not require specialized power, or additional circuitry to operate. They can usually replace a conventional incandescent bulb directly. The expected life span of most halogen lamps is rather low at between 2,000, and 3,500 hours. This is a small compromise, for the improved output you will receive.

Metal halide lamps use a completely different technology to produce high intensity light. This type is classified as an arc lamp, and are quite efficient at converting electrical energy to light output. Arc lamps however, require high pressures, and produce very high temperatures. Metal halide lamps may appear considerably more intimidating, but generally they require no more skill to replace than a conventional lamp.

The name metal halide comes from the element gasses contained internally. Metal refers to the mercury vapor, and halide is a compound that contains a halogen atom, along with a rare earth salt. The types of halides used will vary from region, and manufacturer. The term arc lamp refers to how the light is generated. There are two electrodes inside the bulb, when electricity is supplied, an arc forms between them. The resulting arc will generate heat, which then forces all mercury, and halides to vaporize. This process produces the light, and will grow more intense as the pressure, and temperature increases. Because of this, metal halide lamps have a warm up time, in which they do not produce full light output. Depending on the lamp, and the circuitry it is installed into, this can be from one, or up to 10 minutes.

Not every application is suitable for this technology. They do require proper ventilation for the excess heat produced, and have special power requirements. These are minor inconveniences compared to the long life of a metal halide lamp. Typically metal halide lamps have an expected lifespan from 15,000 to over 20,000 hours.

Halogen lamps generally have a color temperature close to 3,000K. Metal halide lamps have the ability to span a wide range of color temperatures. Depending on the lamp, and its manufacturer, they can range from 3,000K to 20,000K. While metal halide has a considerably wider range, the bulb, and appliance must be rated for a specific temperature. The effective color temperature will degrade as the bulb ages.

While there are advantages to both technologies, there is no clear best choice for a lamp style. Many variables need to be considered, such as case size, light output requirements, and available power. All of this information, and more will help deciding on what type of lamp will suit your needs.