Failing to install a junction box is perhaps the biggest mistake homeowners make.
A junction box can be also called an electrical box or connection box. These inexpensive devices protect electrical connections while containing sparks or heat should a short circuit occur. Installing a plastic or steel junction box adds a step when you are putting in a new outlet or light fixture, but the actual cost of the box is only a few dollars. Plus, accessible junction boxes are required by code in most areas of the United States.
Another problem with an improperly installed juncion box is overfilling it with wires. You should not overfill a junction box. Cramming too many wires into a junction box is not only dangerous, but it’s against the National Electrical Code.
Just installing a junction box doesn’t guarantee safety. The box must be fitted properly so it’s flush with the drywall. Otherwise, combustible materials—like wood—are exposed to potential sparks. If the junction box is recessed too far into the wall, correct the problems with an inexpensive box extension. http://genesiselectric.com/residential/
To prevent overloading, you need to use the same gauge wire throughout a circuit. And take care to use the right size wire for the amount of amps in the circuit. Don’t go on the look of a wire. Know the amp capacity for each gauge of wire. Contrary to what seems logical, the smaller the gauge number, the thicker the wire.