The most common electrical defect we find in both old and new homes here in Port St. Lucie, is the double tap. The term double tap, is electrical jargon for attaching two wires to a single breaker where only one was designed to be attached.
In the electrical panel, branch wires are attached to circuit breakers. Often, the homeowner or repair person needs additional power for new wiring. Assuming that the electrical panel is large enough. The correct procedure is to add a new breaker or replace an existing breaker with one designed to accept two branch wires. Unfortunately this is often not done correctly. The new wiring is attached to a single lug of an existing breaker, creating a double tap.
Double taps can be dangerous. The wires can loosen from the lug that secures them to the breaker. Loose wires will begin to spark or overheat. Double taps are considered a fire hazard and should be corrected by a licensed electrician. In some cases, especially with older homes with smaller electrical service, the double taps may be overloading the panel. The panel may need to be replaced with a larger panel designed to meet the homes current needs.