Splices and joints are two names for essentially the same thing, that is, methods of connecting two pieces of wire so as to carry either a signal or an electrical current. Usually, these types of connections are achieved using a soldering iron. However, it is highly important that the splice or joint be strong regardless of whether solder has been applied or not. Several ways exist in which to accomplish this sort of a connection.
Western Union Splice
The Western Union splice is the most common type of wire splice. The Western Union splice is achieved by stripping about 5 inches of the insulation off both ends of the wire, then holding the exposed inner wires together to make an "X." The technician then wraps the end of each piece of wire around the other side of the joint five or six times, cuts off the excess from both the ends and pinches the end down with pliers. This type of connection is used to splice small, solid conductors together.
The tap splice, also known as the tap joint, connects the end of one wire into another running wire somewhere along its length. In order to create this joint, simply strip about 4 inches of insulation off the end of the connecting wire and about 1-1/2 inches from the running wire. Place the connecting wire to one side of the running wire, wrap the inner wire around itself one time, and then wrap it to the connecting wire in the opposite direction about six times.
Fixture splices, also called fixture joints, are primarily used when connecting light fixtures, but also when connecting two different-sized wires together. To make a fixture splice, first strip about 5 inches of insulation off the ends of both of the wires you are going to connect. Then bisect the scraped section of one of the others by placing it atop the other wire at a perpendicular angle, and then twist the wires together with pliers about three times, making sure that both wires twist. Bend the twisted sections of wire so that they are even with the longer section of wire, and then straighten the excess ends of the twisted sections onto the longer section of wire and twist them in turn onto the wire.
A rattail joint is used with wiring that is placed into a junction box or conduit. Once again, about 5 inches of insulation is removed from both sides of the joint. The two sections of wire are simply crossed into an "X" and twisted together so that they form one section of twisted wire pointing straight up from the endpoints of the wires' insulation.