Double-wiring, also known as “double-lugging,” is 
a condition where there's two wires under one lug screw on a circuit breaker in an electrical panel.
The photo shows there are three instances of double-lugging in this electrical panel.
Double-tapping typically occurs when a non-professional is adding an additional electrical circuit... and a new circuit breaker wasn't purchased or there's no room in the electrical panel for another circuit breaker.
Why is double wiring/lugging a problem?
A little technical talk now... If a wire becomes loose, it can arc. As it arcs, there is a buildup of carbon. Carbon creates resistance making it more difficult for the wire conductor to make contact; thus increasing the electrical current flow... The end result can be the circuit breaker tripping because of the loose connection (excessive current exceeding the rating of the breaker)... There can be signs of overheating such as discolored wires, melted wires, or worse yet...fire!
A good home inspector will make an observation of double-lugging/wiring and recommend further review by a licensed electrician.
Comments(6)