A mechanical shunt for use in a socket of a string of lights resides in an otherwise typical lamp of a string of lights. The present shunt is a horizontal spring held in position by a shunt holder between the two conducting terminals on the interior walls of the socket so that the lateral ends of the shunt contact the terminals when the base is removed. When the base is inserted, a depending prong on the bottom of the base presses the shunt into a V-shaped surface formed in the shunt holder to pivot the lateral ends away from the terminals and allow current to flow through the Dumet wires to the filament.