Three-Way Switch Wiring: Facts and How-To

Tired of having to go back and forth to turn off your hallway light? Learn how three-way switch wiring allows you to control lighting from two different locations.

Having to go up and down your stairs or across a room to turn off your lights can be a nuisance. Save yourself that extra trip with three-way switch wiring. Wiring a three-way switch allows you to conveniently adjust your lights from two different locations, and it may come in handy in a variety of areas, including:

• Both ends of a hallway
• At the top and bottom of a staircase
• On a ceiling light and wall fixture

If you’re ready to make life easier, use our guide to learn about wiring a three-way switch for your home light fixtures.

How to Wire a Three-Way Switch

Learning how to wire a three-way switch can be complicated and require some patience, but this guide will walk you through running an electrical cable and connecting the two switches with step-by-step instructions.

Wiring a three-way switch will take a few hours, depending on your wall framing. If you have open wall framing, you should be able to easily run the cable and complete the task in about 2-3 hours. However, if you have to remove any drywall, three-way switch wiring may take 8-12 hours to allow for wall repairs. Before you get started, here’s what you’ll need:

• Three-way switch (two)
• Remodeling box (two)
• 4-in-1 screwdriver
• 14/3 type NM cable
• Black electrical tape
• Needle-nose pliers
• Wire cutters
• Drywall saw
• Non-contact voltage tester
• Utility knife

Step 1: Turn the Power Off

IMPORTANT: Before you begin, make sure the power has been turned off. After you switch the power off at your main circuit breaker, use a voltage detector to confirm it is off.

Step 2: Decide on the Location

Place your second three-way switch in an area where you can easily run a cable to the existing light switch. Use a stud finder to look for any potential obstacles and find an accessible path. Two ideal paths include:

• Up the wall through the stud cavity, across, then back down to the new switch
• Down toward the floor, across the wall, then back up to the new switch

Once you find an easy route, trace an outline where the remodeling box will go on the wall and use a drywall saw to cut an opening. Then, measure the amount of cable you’ll need – give yourself a few extra feet in case you need more to work with.

Step 3: Replace the Old Switch

With the power turned off, work to first replace the old switch with a new three-way switch. Using a screwdriver, remove the cover plate, then unscrew and remove the switch. Any wires that aren’t connected to the switch should be labeled and unhooked. Unscrew the grounding screw and any cable clamps found inside the electrical box. The old electrical box will be replaced by a remodeling box that you can mount on the drywall without cutting the wall open (Step 5).

Step 4: Run the Cable

For Open Walls: Drill a ¾ inch hole between the two box locations where the stud is positioned. Then, run the 14/3 type NM cable from one box opening to the other.

For Finished Drywall: Use a corded drill to trace along the path you located (Step 1). Drill through the center of the wall plates, then fish the cable through the wall. Leave about 18 inches of cable sticking out of each opening. When you’re done, patch any drywall holes that you created.

Step 5: Sheath the Cable

Insert the cable ends into the new remodeling boxes from the backside and slide the box into the wall opening at the same time. Once the box is firm against the wall, the wires should extend about three inches outside of the box. When the box is in place, drill in the screws.

Step 6: Attach Wires to the Switch

You will have a cable running from your light fixture down to the original switch location and cable running from there to the second switch location. Make sure to expose the ends of your cable. Use a utility knife to expose one bare wire and three colored wires: a red, white and black. Follow these steps to learn how to wire a three-way switch:

• Attach the ground terminal on the three-way switch with the exposed wire
• Connect the black wire from the power coming into the common terminal
• There are two neutral wires: One from the power source and another one connecting the two switches, attach the two together.
• Connect the black wire and the red wire from the cable between the two switches to the traveler terminals on both sides of the switch
• Once the new switch is connected, install it into the remodeling box
• Follow the same steps when wiring the three-way switch that is connected to the light, but make sure to attach the black wire leading to the light to the common terminal. The black and red wires connected to the first switch will be attached to the traveler terminals on each side of the switch.

Step 7: Install the Light

Before putting your light fixture back on, you will need to connect the wires. Simply connect neutral to neutral, ground to ground and hot to hot. Install the light and flip the circuit back on to check your work. If your three-way switch wiring project was done properly, you’ll be able to turn the light on and off from two locations. You may also want to consider installing a dimmer light switch to use less energy and prolong the lifespan of your lightbulbs.

Whether you decide to try your hand at three-way switch wiring or not, be sure your home’s electrical system is covered by American Home Shield®. A home warranty can help protect your budget against the cost of covered repairs, including direct current wiring and light fixtures.