There are many different varieties of light timers and reasons you may need to have them. There is sometimes a bit of difficulty in figuring out how to set a light timer. If you have a dial type of light timer, whether it be for an aquarium or small greenhouse box, then the step-by-step guide below should help.
Plug the light timer up and ensure your bulb does turn on and is not blown out.
Turn your switch to the auto setting. This is the only way your light will go through the cycle of turning on and off at your set times.
Set the pointer on your light timer to the current time.
Press down the tabs located around your dial for the times you want the light to on. At this point you will want to also make sure the tabs are up for the times you want your light off.
Test your light timer by turning the dial after you are done to make sure the lights turn on and off at the right times. Don't forget to set the pointer back to the current time after you have tested and made sure your light timer is working appropriately.