How to Replace a Light Switch
Three-way Light Switch
This handy device is designed to give you control over turning a single light "On" or "OFF" from two separate places; both ends of a long hallway, for example. You may feel as if it would be more accurate to name this a two-way switch, but the moniker refers to the construction of the switch, which sports three terminal screws, thus, our three-way switch was born.
Changing Out Light Switches
1. First and foremost—and before you begin your work—make certain to turn off the electric circuit that serves the switch you will be replacing. Basically, flip the fuse to the "OFF" position inside the circuit panel box. (This applies to any electrical home project, by the way.)
Flip Off The Power
Take Off The Switch Plate
2. Using a screwdriver, remove the switch plate by loosening the screws located at the top and bottom of the plate.
Removing Light Switch Cover
Test For Current
3. Test the switch with a voltage meter or tester to make sure you have the power turned off to the right device and circuit.
4. Now, remove the actual switch casing from the wall by removing the top and bottom screws. It is important to leave the wires attached at this point.
Remove Old Switch And Test For Current
Finding A Green Ground Wire
If you find a green ground wire on the old switch, place it on the new switch's green screw terminal. When a green terminal is not available, attach it to the electrical box that the switch gets pushed into.
Generally, a three way switch has three wires (sometimes four, if there is a green ground wire in the mix). Two of these wires will need to be attached to screw posts which are almost always at the top of the switch. The third wire will be attached to the screw post at the bottom of the switch. The third post (terminal) will be darker (not green though, as this indicates the ground position). It is a good idea to attach a marker of some kind—like a piece of tape—to this wire and another colored piece of tape to the wire on the same side and right above it. This labeling will make the wires easy to recognize when attaching them to the new switch.
About A New Three-way Switch
The majority of three-way switches will have one terminal fixed at the bottom of the switch, with a pair of posts on each side at the top. Your new switch might have these electric terminals (used to screw the wires in place) in a different place than the old switch you are replacing. But, it should be relatively easy to see the correct positioning requirements—with two terminals at top, and one at bottom.
Hey, Where's the Light Switch Ground Wire?
Remove, Then Attach Wires
5. Remove the wires from the old switch terminals. (It might be a good idea to replace each wire one at a time, this helps reduce the chance of making an error in positioning the wires on the new switch.) Attach wires to the new switch terminals.
Remove Wires From Old Switch
Trim Damaged Wires
6. If the wires you removed from the old switch show signs of damage to either the wires or the plastic coating, carefully trim back the damaged area to expose a clean undamaged section. Be careful not trim the wires too short; you will find there isn't much wire length to work with from the beginning.
Trim Damaged Wires Carefully
Attach Wires To New Switch
7. Being very careful not to pull any of the wires from their terminal, wiggle the newly wired switch housing back into the electrical box. Now, secure it in place with screws.
Put New Switch Back into The Wall Box
8. Attach the switch plate adjusting it so it fits evenly over the electrical box's hole. Now, turn the power on at the fuse box, and test your newly replace three-way light switch.