An improvement to the current-carrying components of a lamp includes two filaments connected to two different electrodes and one common electrode, and a switch for directing current through the secondary filament upon the failure of the primary filament. Normally, the current flows through the primary filament. The switch in one embodiment is a wire that does not conduct when the primary filament is operational but conducts on the failure of the primary filament to shunt the current to the secondary filament. The wire is an oxide metal wrapped around two of the three electrodes inside the glass envelop of the lamp. When the primary filament fails, the open circuit voltage breaks across the oxide layer to weld the wire to the electrodes and bypass the primary filament.