How to replace a three-way light switch

So recently our kitchen lights developed a little quirk. They were set up on a three way switch (two switches controlling the same light bank, one at either end of the kitchen), but for some reason if you turned one switch, you couldn’t turn it off from the other, it would just kick back on in both positions. I decided to swap out both of the switches, a) because I couldn’t isolate which of them was causing the problem and b) I’m progressively swapping out outlets and switches over time anyway–after having two separate outlets causing issues when we first moved in, it seemed prudent as a progressive project.

Three way switches are uniquely wired. If you’re putting in an outlet, for instance, or a two way switch, you’ll usually (but not always) have three contacts–the ground, the hot wire, and the neutral. With a three way switch, there’s an additional contact for a “common” wire, which travels between the two switches to allow you to use either switch at any given time.

To do this project, you’ll need a few things:

Hardware:

  • Screwdrivers (Philips head and flat head)
  • Wire cutting/stripping device (I have a tool specifically designed for this, however you can use a pair of needle nose pliers in a pinch)
  • A non-contact voltage tester (Ironically, when I was shooting the video for this, my tester was missing, so I took the risk of electrocution upon myself. If you’re going to do this, do as I say rather than as I do. I promise this is probably the only time I’ve ever attempted a repair without one!)

Software:

Process:

Kill the power to the switch–The first step of ANY project where you’re working on electrical systems is to kill the breaker for the circuit you’re working on. Go to your electrical panel and switch off breaker for the switch you’ll be working on. In my case, I had three separate breakers marked “lights”, so I wound up turning the light on in the kitchen, then letting my bride yell at me from the other room when I flipped the right one. It’s a process that’s only effective when you’re married or have another person in the house to do this with, otherwise you’ll need flip a breaker, go inside to see if the light is still on, and repeat until you find the right one. If you really want to save time and it’s light out, just kill the entire breaker panel–keeping in mind you’ll need to reset all of your clocks, of course.

Confirm the power’s off–Once the power’s off to the switch, check it with your non-contact tester. This doesn’t require direct contact with a wire to recognize a current, so you can actually just hold it next to the switch while the cover plate is still on it to check. If it doesn’t beep, you should be good. If it beeps, go back to the last step–you didn’t turn the right one off.

Remove the cover plate–this is the nice looking cover that keeps people from having to stare at exposed wiring in houses. It’s usually a simple 2 flat head screws per light switch on the panel.

Remove the old switch–Once past the cover, there will be two screws on the switch itself, usually Philips head. Loosen both of these screws until you’re able to pull the switch out. At this point, you’ll see the wires in the back.

There’s a couple ways to approach the process of relocating the wires from the old switch to the new switch. I’ve seen people take pieces of painters tape and mark which wire is the common, which is the hot, etc. In my mind, this winds up taking more time (I mean, really, who has time to individually label the wires in their junction box? I have a six month old, for crying out loud–ain’t nobody got time for that!) The method I use is akin to how I would change spark plug wires on a car–instead of pulling all of them loose at once and risking putting them on in the right order, I take a wire at a time from the old switch and move it to the counterpart contact on the new switch.

There’s a couple ways to install the wires on the new switch–most modern switches have a stab panel in the back where you can just shove the wire into the back. It’s efficient, but I’ve always felt like it’s taking the easy way out. Using the strip guide on the back of the switch, I used the wire strippers to take off the sheathing, then hooked the wire so that it will go around the side contact screws. (You’ll want to make sure that the hook goes the same direction as the tightening screw turns, otherwise it doesn’t like to stay put)

If you’re using the screw contacts instead of the stabby method, you’ll want to put electrical tape around the sides of the switch to cover the contacts. If you stabbed your switches like it’s some kind of tiny plastic voodoo doll, feel free to skip this step.

Put everything back–Remember how you took out the switch and removed the cover? Well, you’re going to do the reverse of that now. (I’ll assume you haven’t forgotten how to use a screwdriver in the past five minutes and spare you the lengthy explanation…)

Restore power–Go out and turn on whatever breakers you turned off in the breaker box. If you killed power to your whole house, go back and set your clocks.

And there we go–good as new!

Disclaimer: Almost any DIY project involves risk of some sort. Your tools, materials, and skills will vary, as will the conditions at your project site. The Hesitant Handyman has made every effort to be complete and accurate in the instructions provided on this website. The Hesitant Handyman will not assume any responsibility or liability for damages or losses sustained or incurred in the course of your project or in the use of the item you create. Always follow the manufacturer’s operating instructions in the use of tools, check and follow your local building codes, and observe all commonly accepted safety precautions.

If I’m linking to a tool or material, there’s a good chance it will direct you to Amazon—using the magic of affiliate linking, your use of the links in the post lets Amazon know I sent you their way, and if you buy something within 24 hours, I’ll receive a commission. It doesn’t cost you anything extra, but it helps us keep the lights on.
Rest assured, I’m not going to randomly pitch you on something that I don’t think you could use—Whenever possible, I try to link to the tools I use myself. If it’s something I don’t have, I only recommend tools from brands I trust.

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