How to Change Out Light Switches
Before you do anything, you'll need to buy a 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.
1. Turn Off the Electric Circuit
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.)
2. Take Off The Switch Plate
Using a screwdriver, remove the switch plate by loosening the screws located at the top and bottom of the plate.
3. Test for Current
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. Remove the Switch Casing
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.
5. Remove, Then Attach Wires
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.
6. Trim Damaged Wires
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.
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.
Hey, Where's the Light Switch Ground Wire?
7. Attach Wires to New Switch
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.
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.
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.
8. Put New Switch Back Into the Wall Box
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.
What You Think Really Does Matter!
Kelsey Elise Farrell from Orange County, CA on May 18, 2015:
Great hub with great information and easy to follow instructions. Up-vote!
Tish Huff from Norwalk, Ohio on March 12, 2014:
im hoping i can find some help here I wanted to install a ceiling fan in daughters room. Not a big deal Ive done it before, well anyway installed it all worked but ceiling fan in the room next to hers wouldn't work lights tried to turn on was like not enough power going to it. That fan is connected to a two-way switch. so I decided to unhook the ceiling fan and just put the light fixture back well can't get it hooked up right so its completely unhook and capped right now but still no power at all in the other fan. Its an older home with no ground wire in the wiring the light box in the bedroom has all the black coated wire tied together then has three white coated so im thinking somehow they are all tied into the other fan idk and help would be great
Cheryl J. from Houston, TX on December 23, 2012:
Great instructions and easy to follow. Very informative hub and photos.
Sinea Pies from Northeastern United States on December 23, 2012:
This is an absolutely great step-by-step. We just had our electric redone in our home and some three way lights installed. Just learning which one was which was boggling. I cannot even imagine doing the installation myself however your explanation makes it so possible. Voted up, useful and interesting! :)
Nell Rose from England on December 23, 2012:
What a great step by step guide! I always find stuff so much more helpful by looking at it, so this is great! voted up and shared! nell
Martin Kloess from San Francisco on December 21, 2012:
Thank you for this step by step guide.