Abstract: An alarm actuated emergency light signalling circuit to replace the usual wall mounted light switch. The new switch circuit fits within the electrical wall box and has the external appearance and manual operation of an ordinary light switch. When triggered by an alarm system, the new light signalling circuit overrides the circuit breaking function of the light switch and causes the lighting controlled by the switch to flash intermittently. The flashing of the lighting occurs regardless of the initial state of the light switch, whether on or off. The circuit includes a low voltage portion driven by the alarm and including sensing and timing circuitry. The low voltage circuit does not require or use any electric power when not actuated by the alarm. The alternating current power circuit for the lighting is operable in the conventional on/off fashion unless actuated by the alarm and low voltage circuit. Thus, there is no additional alarm position for the switch.