Landscape Lighting, continued

Low-Voltage Fixtures

We accomplish these goals with low-voltage lighting systems that are easy to shop for, and that you don't need an electrician's license to install. The systems use 12-volt direct-current power, supplied by a transformer that plugs in to an ordinary GFCI-protected 120-volt house outlet. (We do ask for dedicated outlets to serve our transformers, and of course those circuits have to be run by a licensed electrician.)

We'll get to transformers in a moment; first, let's take a look at lights. The business end of the system starts with the fixtures. These fit into three broad categories: path lights, spotlights, and specialty lights (Figure 4).

Figure 4.Most elements of a nightscaping design are accom-plished with a combination of path lights and spotlights. At left, the author has blended both fixture types into his arrangement of stone terraces, walls, steps, and walkways. Specialty lights allow subtle custom touches in every kind of space. Above, a deck is lit by fixtures recessed into railings.

Most path lights are mounted on short, vertical stems and are designed to cast light down onto a small section of walkway or path. These fixtures usually receive a bayonet-style lamp, like the old taillight lamps that cars used to have. Dozens of lighting companies offer many minor variations on the classic path light theme, and some offer more elaborate or decorative fixtures that set the hardware into a small statue or other object. Simple fixtures work fine, but it's worth placing them with care. I avoid lining up the fixtures, which can create a "runway effect," unless the client happens to like that.

Spotlights can be used for almost any application, including uplighting, downlighting, backlighting, and highlighting. They are typically applied for the visual effect, but a spotlight placed as a downlight in a tree or other elevated spot can also be used to light pathways.

Specialty lights are really a variation of the path light or spotlight idea, refined for a particular location or use. Some fixtures are designed for mounting into steps or walls; we use those as path lights or spotlights. We also have fixtures that we can mount under deck railings or recess into the railing. These highlight the railing detail, as well as shrubs or sculptures below them, and they cast a subdued light into the nearby walking or sitting areas. Other available options include strip lighting (similar to holiday lights) and underwater lights.

We can flexibly mix and match all these broad fixture types in various designs, to meet the needs of the particular case. The only rule is to choose what works: To get the look and function I want, I use spotlights to light pathways, path lights to highlight plants and sculptures, and rail and step lights to do either.

Low-Voltage Lamps

The core components in any system are the lamps (the bulbs that go into the fixtures). Twelve-volt lamps are more powerful than you might think: On average, a 12-volt lamp will put out as much light as a 120-volt lamp of three times the wattage. So for example, a 25-watt 12-volt lamp will throw as much light as a 75-watt 120-volt lamp.

Certain lamps fit certain types of fixtures (Figure 5), so your choice of lamp will actually dictate the type of fixture you can use. You start the design by considering which of several main lamp types will best achieve the intended effect in each location you intend to light.

Par-36 lamps are the same as your car's headlights: They will throw a beam a long way and are great for uplighting trees. Available wattages range from 15 to 50 or more watts, with beam spreads ranging from 5x5 degrees up to 69x69 degrees. They are extremely versatile for use as spotlighting, highlighting, path lighting (when hung in a tree), and shadowing. Par-36 lamps are maintenance friendly and last quite a long time if they're not over powered. Their one drawback is that they don't last as long as halogen lamps.

MR-16 lamps are high-intensity tungsten halogen lamps, which give a truer white light. These are excellent for highlighting bricks and other colors at night. We use MR-16s on occasion in all the same situations where we use Par-36 lamps. Smaller MR-11 and MR-8 lamps are also available and are useful when the application calls for a compact fixture. One of the advantages of an MR-16 is that they are small and easy to conceal. These lamps must be in a watertight fixture, and it's worth choosing high-quality fixtures that won't corrode shut and make access impossible when it's time to replace a lamp.

Bayonet lamps are used mostly for path lighting, but they can also be used for low-level spotlighting (on a sculpture, for instance). One problem with these lamps is that they're not intended to be sealed into a fixture; the heat generated will make them fail prematurely. We specify halogen and gas-filled (xenon) lamps because of their longer life and brighter light. T-series lamps such as T-3 and T-5 are either wedge-base or bi-pin and come in a large wattage range.

Fiber optics. Recently, there has been a movement toward using fiber optics for landscape lighting. The technology brings two major advantages: First, the emitting fixtures are extremely small and easy to hide. This works especially well with waterfalls. Second, there is only one source lamp to worry about. The illuminating unit houses a powerful halogen lamp (typically either 150 or 250 watts), and the fibers are run off of that. You can run virtually unlimited fibers from the illuminator, as long as you can fit them in front of the lamp.

But there are disadvantages. The illuminator is a sealed unit with a very hot lamp. All units incorporate a cooling fan, and because the fans make noise, you need to isolate them from gathering spaces. Also, if you cut a fiber, you can't make a splice that will completely restore the fiber's light transmission ability — you need to replace the entire fiber. (Low-voltage wire, by contrast, can be spliced at the point of damage.) Finally, fiber-optic systems cost quite a bit more than ordinary low-voltage systems. Don't let cost deter you from giving them a try, however, especially in wet areas. Fiber optics are a safe way to run lighting to pools and ponds.

There has been a lot of recent hype about LED lighting for landscapes. We've been flooded with advertising emphasizing LED technology's extremely low power usage. One flyer I received claimed that a 1-watt LED lamp would provide as much light as an 18-watt bayonet lamp. I was intrigued enough to order some lamps and test them in our display gardens. After experimenting with multiple lamps in various configurations and color combinations, and after many discussions with the manufacturer, I concluded that LED products have a long way to go before they will be effective for my kind of work.