Halogen lamps, CFLs, MH lamps, and LEDs are all used in track lighting (Table 1). Each has strengths and weaknesses.
Table 1: Choosing the right lamp type
When choosing track lighting, it’s important to consider how you’re going to use it—each type of lamp is appropriate in different applications (A). Lamp types—halogen, compact fluorescent, metal halide, and light-emitting diode—also differ in efficacy, life, and color quality (B).
Advanced halogen lamps. Advanced halogen lamps use advanced halogen infrared (IR) technology. IR coatings redirect wasted heat energy emitted by the lamp filament back to the filament to increase its temperature and thus increase light output without increasing wattage. These products provide a 20 to 30 percent increase in efficacy but cost 2 to 3 times more than standard halogen products. More-efficient versions are in the works.
Metal halide lamps. MH lamps, especially ceramic metal halide (CMH) units, have improved greatly in recent years and can compete with halogen lamps in most applications except those where deep dimming is called for—MH lamps suffer from an undesirable color shift when they are dimmed; they are generally not dimmable below about 50 percent of initial output. CMH lamps offer better color quality and exhibit less color shifting than conventional quartz MH lamps, and their light output degrades more slowly. CMH lamps provide good color quality, long life, and a widening variety of lamp shapes and sizes, including MR16, PAR20, PAR30, PAR38, T-6 single-ended, and T-6 double-ended, all of which have been incorporated into track lighting designs. Newer CMH lamps that draw as little as 20 watts have enabled the technology to compete with halogen lamps and CFLs in a wider range of applications. Some of the low-wattage, self-ballasted CMH products may have low power factors, so harmonic distortion and high neutral currents could be a concern if they are deployed in high concentrations (check the lamp specifications for power factor).
Compact fluorescent lamps. CFLs are not a good choice for track lighting applications where concentrated beams of light are needed, but these lamps are suitable for track lights used for flood-type light distributions and wall-washing. CFLs are also of limited value where dimming is required—dimmable CFLs cost more, and they generally don’t dim as deeply or as smoothly as halogen lamps. Fluorescent lamp track heads often require baffles to reduce glare for shoppers or room occupants.
Light-emitting diodes. LEDs have a number of properties that make them good candidates for track lighting applications. Their light output is directional, so the lamps can theoretically be designed to match any of the light distributions of conventional lamps and even provide new distributions. However, it’s important to test products to make sure that they provide the desired light spread. LEDs emit neither ultraviolet (UV) nor IR radiation, so they can be used in museums and other areas with UV-sensitive objects as well as in grocery stores and other applications where objects are sensitive to heat.
LEDs are not quite ready to replace small, high-wattage halogen lamps. The challenge for smaller-sized LEDs, such as those aiming to replace halogen MR16 lamps, is that LEDs require large heat sinks to dissipate the waste heat they generate. In addition, it has proved difficult so far to pack enough LEDs into a small space to replace small, higher-wattage lamps.
Track lights for energy-efficient lamps are similar to track lights for halogen lamps (Figure 1). The track can be recessed into the ceiling, mounted to the surface of the ceiling, or suspended from the ceiling in a configuration known as a pendant mount. The track head—which includes the lamp housing, lamp, socket, and a reflector cone—moves along the track and may be integrated into the track or suspended in a pendant mount. In addition, some individual track lights can be connected directly to a junction box. Ballasts are typically housed in the track head, although they may also be recessed into the ceiling plenum. Track lights also offer options for switching individual lamps or groups of lamps.
Figure 1: LED track lighting fixture
Track lights for energy-efficient lamps are similar to those for halogen lamps. This light-emitting diode (LED) fixture was a prizewinner at the Next Generation Luminaires competition.
Accessories available for track lights include lenses that alter the beam shape, louvers and tubular shields that cut down on glare, and filters that change the color of the light. Some products also offer a ballast fuse that prevents damage from voltage surges.