A leakage current is a current that flows from the conductors in an electric circuit to the earth circuit or to conducting elements (chassis, metal beam etc.).
This leakage current may be caused by an insulation defect, moisture, more or less conductingdeposits etc. It represents a waste of energy and can sometimes be dangerous to persons.
Corrosion and deposits that have accumulated on old sockets are the cause of increases in leakage currents. © Bill Shirley CC by-nc-nd 2.0
Leakage current - 1 Photo