In most installations you will need to join sections of cable. To do this, just strip half an inch of insulation off each wire. Then use a waterproof wire nut to connect the two wires. It is important that you use a waterproof wire nut since the wires will be buried outside. If you don’t the system can short out every time the grounds gets wet.
Try to place the join in a spot that does not get waterlogged, so stay away from gutter downspouts and the like. This will help prevent the system shorting out every time it rains.
It is important that you use actual waterproof wire nuts. The weatherproof wire nuts have a lid and are filled with gel to protect the spliced wire from water infiltration. You can get waterproof wire nuts at most larger hardware or electrical supply stores. For example Home Depot stocks the Ideal -WeatherProof Wire Connector” (available only instore). Waterproof wire connectors are cheap and will set you back less than a dollar a piece.
To join the two sections of wire, simply strip the half an inch of insulation off the end of each section or wire, and insert the stripped end into the wire nut. Now gently twist the wirenut until the wires become firmly joined. (you will feel gentle resistance) Overtightening will snap the wire and undertightening will result in a poor join.