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Posted by Doug Root on 13th Jul 2021

Metal Halide Ballasts and Positioning: What You Need to Know

Metal halide lamps are a type of arc lamp known as a gas discharge lamp. The bulb that comprises the lamp contains electrodes as well as a mixture of metal halides (salts) mercury vapor, and an inert gas to sustain the process, such as argon.

When the lamp is turned on, an electrical current (an arc) forms between the two electrodes within the bulb. This art heats up the metal halides and mercury contained within the bulb and excites the atoms contained within, causing them to glow and improving the color temperature and the luminous intensity of the lamp.

Why Does a Metal Halide Lamp Need a Ballast?

These types of lamps, which are a class of HID or high-intensity discharge lamps, are very effective at producing a relatively efficient emission of high quality, very intense light. However, they are very different from the incandescent and LED lights with which most homeowners may be familiar.

Metal halide lamps need a special component known as a ballast that provides the appropriate voltage to start the lamp, regulates the current supplied to the lamp during operation and supplies the proper voltage during the time that the lamp is switched on.

Without a ballast to regulate the supplied current and sustained voltage, the lamp would quickly burn out. The ballast not only protects the lamp from immediate damage but helps to improve and extend lamp life while it also promotes the effective operation of the lamp by enabling it to provide consistent out and color temperature.

What Types of Ballasts Are There?

No two metal halide lamps are the same, and therefore no two MH lamps will accept the same ballast, necessarily. You can consult the ANSI code of the lamp for specifics regarding the type of ballast the lamp needs, along with any other proprietary information regarding the fixture the lamp requires.

Core and Coil Ballasts - Core and coil ballasts are among the most common types of metal halide ballast available today, consisting of a transformer to control the voltage (the core and coil) as well as a capacitor. These are also typically mass-produced and affordable, but since they are produced to fit into standard commercial lighting fixtures, adapting them to other situations will require the creation of new housing.

Electronic Ballast - Electronic ballasts have only recently become available for metal halide lamps. Although there have been some concerns reported regarding the electromagnetic interference (EMI) that may be produced by these ballasts, it has also been claimed that they are reliable, energy-efficient and produce less heat than conventional core and coil ballasts. They may also be able to extend lamp life and light output while providing functionality to dim the lamp.

Between these two different types of ballasts, there are many different additional types, including but not limited to constant-wattage isolated transformers, constant-wattage autotransformers, linear reactor pulse starts, and magnetically regulated ballasts. Don’t be fooled by the name of the latter - unlike magnetic fluorescent ballasts, magnetically regulated metal halide ballasts are among the most advanced of them all.

What about Base Shape and Orientation?

Unlike other types of lamps, like incandescent, halogen lamps, and LEDs, metal halide lamps should only be burned in a specific position or orientation. It is common for MH lamps to be operated in a base-up position, in which the bulb itself is facing down, but this is not always the case. MH lamps may also have the potential to burn in horizontal positions, base-down configurations, or universally. Some lamps are also able to be burned on a slant.

The orientation of the MH lamp in question is vital to its operation. Not only can it affect the operation of the lamp itself, but it can also have a pronounced effect on lamp life as well as color variation and color shift. That is to say, if the lamp is not burned in the proper orientation, it may not produce the desired color temperature or light output, and it may also not last as long as expected.

Additionally, the base shape of a specific metal halide lamp will also dictate what fixture is required to install and operate it. This information can be gathered from the ANSI code that accompanies the metal halide bulb itself.

If you have any questions about lamp bases, color temperature or color rendering, color shift, color variation, or lamp positioning, please consult our customer service team for additional assistance.

Contact Atlanta Light Bulbs for Additional Assistance

Metal halide lamps produce bright white light and are an efficient light source for street lights, parking lots, sports arenas, and other large outdoor spaces.

They are not all the same, and they do not all accept the same fixtures and components. If you have any questions whatsoever regarding our products or the lighting infrastructure your unique circumstances require, please contact us at 1-888-988-2852 for more information.