Timer Switches are very useful when you want to turn lights on and off when you are not home or to activate sprinkler systems during the night in hot sunny regions so the sun doesn't burn the grass. In time, the timer switches internal parts can wear out and it will stop working. You need to inspect the switch to make sure it is the switch that stopped working and not something else. Most timer switch owners can test the switch by themselves in about a half an hour. If you own a timer switch and it doesn't appear to be working anymore, here is how you can test it to see if it needs to be replaced.
Turn Off Power
You will be working with a "hot" black wire. If you touch this wire while the electricity is on, you could electrocute or shock yourself. Make sure you turn the circuit breaker off that feeds power to the timer switch.
Removing the Timer Switch
The timer switch is connected to an electrical box with a couple of screws. Remove the screws with a flat head screwdriver and take the timer switch off of the electrical box. Inside the electrical box are the wires for the switch. There are three different sets of colored wires: one is white, one is black, and one is copper. They are connected to corresponding colored wires inside the electrical box and the connections are held together with wire nuts. Unscrew the wire nuts and pull the wires apart so you can completely remove the timer switch from the electrical box.
Testing the Timer Switch
You need to use a continuity tester to make sure an electrical current can flow through the switch. Turn the dial on the timer switch to the "On" position. Take the alligator clip portion of the continuity tester and clip it on exposed wire at the end the red lead wire. Touch the tip of the continuity tester to the exposed wire on the end of the black (hot) wire. If a current can flow through the switch, the light on the continuity tester will light up. If it doesn't light up, you need to replace the timer switch.
Now, turn the timer switch to the "Off" position. Keep the alligator clip on the exposed end of the red wire and touch the tip against the exposed end of the black wire. If the light on the continuity turns on, you need to replace the timer switch. Call an electrician, like Trilogy Electric LLC, for more help.