Installing Low-Voltage Lighting

A low-voltage (12-volt AC) lighting system offers advantages over a 120-volt AC system more commonly used indoors. For starters, because it carries less power, the cable can be buried just below the surface, rather than in a deep trench. (You should still check with your utility providers for locations of any currently buried cables and pipes before digging, regardless of depth.) A 12-volt AC system also uses less energy. Because you're dealing with greatly reduced voltage, the risks of working with electricity are minimized. But don't expect this system to give you the same intensity of light as 120-volt AC lights would provide.

If needed, low-voltage wires can be spliced. Simply strip the wires, put in a silicone-filled cap—sold as a "grease cap"—and then attach the new wire. Some caps are brand-specific, so make sure you buy a cap that is designed for the wire you are using.

Most low-voltage lighting systems include a transformer that is plugged into a regular outdoor electrical outlet. The transformer reduces, or "steps down," the 120-volt household current to 12 volts. (For this reason, these are sometimes called "step-down transformers"; check to be sure yours is one of these and not a "step-up" model before installing.) Most transformers are rated to handle a load of 100 to 300 watts; the higher the rating, the longer the cable—and thus the more light fixtures—you can connect to the system. If you want to add more lights, you may need a bigger transformer; if so, it's probably more economical to buy a whole new system in a kit.

Some transformers come with a photoelectric "eye" that turns the system automatically at dusk. A length of cable runs from the transformer to a string of lights. Cover the cable with a few inches of dirt once the installation is complete. Most low-voltage light fixtures snap onto the cable, but some system require wire connections.

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