Low-voltage landscape lighting systems are a great way to add accent lighting to your yard or garden. Systems will typically come with pre-cut lengths of wire, which can limit your placement of accent lights. To extend the low-voltage landscape lighting wires, you can splice in additional sections of wire.
Stretch out the existing low voltage landscape lighting wire (make sure it's disconnected from any power source first). Cut the wire in the middle with a pair of wire cutters.
Strip the insulation from each of the cut ends of the wire, so that each wire's leads have about 2.5 cm (1 inch) of bare wire exposed. Pull apart the leads of each wire so that they are separated from each other for about 10 to 15 cm (4 to 6 inches).
Take the wire you'll be inserting into the circuit. It should be of a similar gauge and construction. Cut a length that's long enough so that when inserted between the cut sections of the original wire you'll have enough wire to place your light in its destination. As in Step 2, separate the leads of the wire on the ends and strip about 2.5 cm (1 inch) of insulation from the leads.
On each of the leads of the new piece of wire, slide on a 5 cm (2 inch) long piece of heat-shrink tubing. There will be four pieces in total -- two on each end of the new piece of wire.
Twist together the old and new wires to create a continuous length of two-lead wire. At each joint, apply a hot soldering iron, heat the wire, and then apply solder until it flows into the joint. Remove the soldering iron and repeat.
When the joints are cool, slide the pieces of heat-shrink tubing over the joints and direct the heat of a blow drier onto the tubing until it shrinks tight over the joints.
Plug your low-voltage system in and test operation, then place the wire and lighting fixtures as required.
Heat shrink tubing will protect the splices you've made much more effectively than duct tape, especially in the outdoors.
Even though this is a low-voltage application, don't work on live electrical circuits.