Lay Out the Cable
1. Following your lighting plan, mark the cable locations in your yard with agricultural lime. This step allows you to plan the placement of the cable so it avoids natural barriers. Pinpoint the fixture locations with dowels or stakes.
2. Lay the cable. It's safe to lay low-voltage cable directly on the ground, but it's more attractive if it is buried. If you decide to bury the cable, dig a narrow trench along the chalk line. Place the cable in the trench, leaving a 1-foot loop at the transformer and a loop at each fixture location. If cable stretches along the underside of a deck, for example, you can staple the cable in place (see Photo 1), leaving loops for all connections. Take care not to puncture the cable when stapling it in place.
Follow this method to attach any fixture to the cable:
3. Cut through the cable to prepare for attaching a light fixture to the circuit. Study the cut end of the cable, and you'll notice two separately insulated conductors. Cut or pull the cable apart so that the two conductors can be stripped. Using a wire stripper, strip the insulation off the conductors to expose 3/4 inch of wire at the end (Photo 2). Note that you need to strip the cable that leads into the light fixture as well as the cable that leads away from the fixture. Strip the insulation off the fixture's wires to prepare to connect to the low-voltage wire. (Practice stripping the insulation so that you can strip it cleanly without nicking the wires.)
4. To make the wire connections that bring power to a light fixture, take one stripped conductor from the 12-volt cable leading into the light fixture, and one stripped conductor from the 12-volt cable leading away from the light fixture. Hold the wires side by side, twist them together to ensure a good connection, and screw a wire nut over the wires (Photo 3). Make sure that no bare conductors are exposed and that all wires are locked in. Repeat this procedure with the remaining three wires.
5. For a weathertight connection, wrap electrical tape around the cable to seal the joint between wire nut and cable (Photo 4).
6. The cable should end at a light fixture. When wiring the last light fixture, twist two pairs of wires together (one pair from the light fixture and one pair from the cable) rather than the three pairs needed for a light fixture wired in place along the circuit. Do not run the cable beyond the last light fixture. If you decide to add fixtures later, simply unwire the last connections and add a new cable.