Not all of my light switches have updated wiring. Therefore I could not install a programmable light switch. How is it installed? The AutoChron Programmable Wall Switch Timer screws into the bottom of the light switch making it secure. Remove the bottom screw from you switch plate, pull open the front panel on the timer switch and you'll line an opening with the bottom opening on the face plate. Screw the timer switch into position.
How does it work? A plastic piece sits over the switch. Program the on and off time for every day of the week as a whole or individually. When the timer turns on and off, the plastic piece moves up and down, flipping on and off the switch. Yes, there is the sight of a white box sitting on your light switch. However, I think it's a perfect alternative for programming my front porch light to turn on and off.
The switch timer runs on batteries.