A string set of series-connected incandescent flasher type lamps in which substantially all of the lamp filaments in the set are individually provided with a voltage regulated shunt circuit, which includes a voltage responsive silicon semiconductor device, which operates in one of two conducting states, neither of which is greater than about 200 ohms. When the flasher lamp is in the "on" or illuminated state, the silicon semiconductor voltage regulating shunt device is in a low impedance state. When the flasher is in the "off" state, the impedance of the silicon semiconductor device is in a lower impedance state equal to or slightly greater than the parallel equivalent impedance of silicon semiconductor device in parallel with the normal operating impedance of the flasher lamp.