Wiring a double light switch is a simple job that the average homeowner can do. However, it's important to use extreme caution when working with electricity. The required materials are a voltage tester, screwdriver, electrical tape, wire cutter, wire stripper and grounding wrist strap.
Shut off the power
Locate the main junction box for your home. If the breakers are labeled, find the breaker that supplies the area you are working in and flip it off. If the breakers are not labeled or labeled incorrectly, flip off the main power supply breaker.
Check to make sure power is turned off
Loosen the screws on the face plate of the light switch to remove it. Put the wrist strap on and connect the other end to bare metal in the box. Follow the instruction for your particular current tester to make sure power is turned off. Verify that there's no electricity present before proceeding.
Identify the wires and inspect the old switch
Note where all wires hook up on the existing switch. The hot wire is either red or black. The grounding wire is yellow, green or bare, and the white wires are neutral. Place a piece of electrical tape on the hot wire for easy identification later.
Wire the switch
Loosen the screws on the new switch and wrap the wires around them the exact same way the old one was wired. If your setup does not include a grounding wire, make one by cutting a piece of wire and stripping it down to bare metal. Tie one end onto the box and twist the other end onto the green screw on the light switch. Tighten the screws, replace the face plate, and turn the power breaker back on.