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.


Expert Tip


A friend has a long walk that leads to his garage. He wanted to light the path with low-voltage lighting and bought a kit, plus a few extra lights. Unfortunately, when he turned the system on, the lighting was extremely dim. The reason? The transformer couldn't supply enough power for a long cable with so many lights. Ask the salesperson if the transformer you're planning to buy will do the job you want it to do. If not, ask them to recommend a model with a higher wattage capacity.





Step 1: Wire the Transformer

Wire the transformer

A transformer steps the voltage down from 120 volts to 12 volts. Attaching the cable for the lights is an easy task of screwing the wires in place. Details vary by manufacturer, so follow the directions that come with the transformer.


Step 2: Hang the Transformer

Hang the transformer

Mount the transformer on the wall next to a GFCI outlet. For most types of siding, you can make the attachment with a wood screw. Drive it into the plywood or the sheathing underneath the siding. For masonry, drill a hole for a lag shield, then screw into the shield.


Step 3: Assemble the Lights

Assemble the lights

Light fixtures usually require assembly. You'll need to snap the sockets in place at the very least, and you may need to do some simple wiring. Follow the manufacturer's directions.


Step 4: Place the Lights

Place the lights

Lay the light fixtures in the approximate spots where they will be installed, and run the cable across the ground from light to light.


Step 5: Connect the Lights

Connect the lights

Attach the cable connectors. For this light, put half the connecter on each side of the cable, and snap it together to connect the lights.


Step 6: Dig For the Cable

Dig a 6-inch-deep trench for cable

Dig a 6-inch-deep trench alongside the cable, place the cable in the trench, but do not bury it yet.


Step 7: Set the Timer

Set the timer

Plug the transformer into the outdoor receptacle, and set the timer. Cover the GFCI outlet with a plastic cover, usually sold separately. Test the lights; if they work correctly, bury the cable.