Abstract: For operating a switch which has a switch lever, such as a toggle switch lever, The invention provides a device which fits over the switch with the switch lever engaged by a slide on the device. Manual operation of the slide moves the switch lever from OFF to ON. The same operation of the slide starts a timer and sets a return mechanism which is retained at its set position by a latch until the timer at the end of a preset time interval actuates a release mechanism which retracts the latch. The return mechanism then returns the slide to turn the switch lever OFF. All of the operating parts, including a self-contained power source are within a housing that fits over the switch. In preferred embodiments the timer is a microcomputer chip. An optional time interval selector is described for presetting a selected time interval for the timer. A single manual movement of the slide causes the device to automatically execute the rest of its cycle.