Abstract: The timed AC switch comprises a manual on-off switch in series with bidirectional semiconductor switch, such as a triac, for connection in a loop with an AC source and a load which would generally be incandescent or fluorescent lamps. The semiconductor switch is driven by an RC oscillator which is under the control of an inhibit circuit and a digital counter which itself is driven by the oscillator. The counter is reset at initial start up, and may also be reset while operating or after counting out. The times switch may also be controlled to inhibit the oscillator for a very short time as a warning before finally timing out.