Track lighting is one of the most commonly used and misunderstood of the lighting system types. It is a powerful tool for a lighting designer but can also be rather confusing without an understanding of some basic track lighting principles. Because track lighting is very directional, track systems perform best as accent lights or task lights. They do not work well providing general light in large rooms. Also, track lighting requires the assembling of different components to make a complete system.
Track is a surface mounted channel that holds the lighting units (or 'heads') in place and brings power to them. Because it is surface mounted, track is particularly easy to install, especially in remodels. The track is usually mounted to the ceiling but it can be mounted to a wall, a beam or dropped from the ceiling on stems or cables. Power is usually fed to the track from the end (an "end feed" or "live end") but it can be powered from anywhere along the channel with special adapters. There are also adapters that allow for various track layout configurations; corners ("L") and branches ("T") are the most common. Normally the various track components are only compatible within a given product line, which means that company A parts will not fit on company B track.
There are a dizzying variety of track heads to choose from though the differences are mainly cosmetic. Two track heads may look very different, but if they hold the same lamp (or light bulb), then the light output will be much the same. Most track heads use directional lamps of some kind and in general I recommend the PAR lamps as a starting point. They are line voltage halogen or LED, are energy efficient, have good optics and excellent color quality.
When the lighting needs are particularly demanding my other favorite lamp is the low voltage halogen, (usually the MR-16). This lamp is mainly used as an accent light because its precise beam control causes shadowing that can interfere with tasks. Most of the heads that use the low voltage lamps have the transformer built into them so they can be used on the same track as the PARs. Both the PAR and MR-16 lamps are available in most hardware stores.
Remember, all light fixtures, but particularly track are just glorified light bulb holders, you are choosing the proper lamp and finding a way to hold it in space. Ideally one would pick the appropriate lamp for a given application (task, accent, wall wash) and then find a track head that will hold it. There are many track heads that hold fluorescent lamps, and these are quite cost-effective in commercial applications.
The beauty of a track system is its versatility. The track layout can be expanded or reconfigured, one can move the heads around, add more, change types, point them in different directions, and so on. This flexibility can be the cause of some problems when it comes to placement. To avoid glare and shadows track lights should shine at a near wall or directly down on a work surface. Keeping in mind that track is mainly an accent and task light, in most rooms the points of interest (artwork, furniture, architectural details) are at the perimeter as are the tasks, so the track should be placed 18 -36 inches out from the wall for most normal room heights. The higher the ceiling the farther out. The down side of track is that one sees the fixtures and it can look a bit cluttered especially in a low ceiling application. However, in the proper setting a well-planned out track system can add much to the decor. Much of this information applies equally well to recessed lighting.
by Eric Strandberg, The Lighting Design Lab