Running down the stairs to turn off a light is a bit inconvenient. Thankfully, learning how to wire a 3-way switch means you can control the same light fixture from two different switches.
Three-way switches are useful at the top and bottom of stairwells and in rooms with more than one entrance. Follow this guide to install one of these specialty switches in your home.
Preparing to Install a 3-Way Light Switch
Tasks that involve electricity require a heavy focus on safety. Wiring a 3-way switch should only be done by those with past electrical experience. Review home electrical safety tips and ensure you have the proper electrical skill set before proceeding.
The following steps will guide you through replacing an existing light switch with a 3-way light switch. To properly set up a 3-way wall switch, you may need to add an electrical switch box for the new switch, if one doesn’t already exist, and install 14/3 electrical cable—meaning a 14-gauge cable with three primary wires and a ground wire—between the existing switch and the new switch. Feeding electrical wires through existing walls is a challenging task for most homeowners. Consider hiring a local electrician to complete this step of the process.
How to Wire a 3-Way Switch
Follow these steps to ensure this DIY electrical project runs smoothly.
Disconnect the Power Source
When working with electrical, always start by disconnecting the electrical supply to the device you’re working on. Flip the breaker switch at your electrical panel that powers the light fixture and switch you will be wiring. Once off, test the light fixture and existing switch with a voltage tester to ensure there is no active current.
Remove the Old Switch
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Using a screwdriver, unscrew and remove the old switch’s wall plate. Next, unscrew the mounting screws. Gently remove the entire switch receptacle from the wall, but be careful to leave the wiring attached for now.
Identify the Wires
Before disconnecting the wires from the back of the switch, it’s important to identify the electrical wires. Doing so makes wiring the new switch much easier.
Label the wire connected to the black or dark-colored screw as the hot wire. Label the wire connected to the brass or light-colored screw as the traveler wire. Use tape to label each wire or take a picture with your phone.
Disconnect the Wires
Once labeled, you can disconnect the wires from the old switch. If the wires are attached to a screw on the back of the switch, loosen the terminal screw to disconnect the wires. If the wires connect to the back of the switch via stab-in connectors, insert a flathead screwdriver into the slot above the wires to disconnect them.
Inspect and Prepare the Wires for the New Connection
To prepare the existing wires for the new switch, ensure 3/4 inches of the copper conductor is exposed at the end of each wire. If needed, remove some of the insulation coating with a wire stripper to expose the copper.
Bend each wire into a hook with needle-nose pliers. The hook should fit snugly around the screw terminal on the back of the new switch. Skip this step if you will be using the stab-in connectors on the back of the new switch and keep the wires straight.
Connect the Wires to the New Switch
This process is similar to how you would connect wires to a standard light switch. Grab the new 3-way switch and loosen the screw terminals on the back. Attach the hot wire to the black or dark-colored screw on the new switch.
With needle-nose pliers, tighten the wire hook, so it fits snugly around the screw terminal. Tighten the terminal screw until it’s difficult to turn and firmly holds the wire in place.
Repeat this connection process by attaching the two traveler wires to the brass or light-colored screws and the bare copper wire to the green screw at the bottom of the switch.
If you’re using the stab-in connectors on the back of the new switch, make the wire connections at the same locations, but insert the wires straight into the stab-in slots without bending them.
Wrap the Switch With Electrical Tape
This step is optional. For added protection and to ensure none of the wires come loose, you can wrap the body of the switch with electrical tape. Be sure to cover the screw terminals and any bare wires.
Mount the Switch and Wall Plate
Insert the switch into the electrical wall box and install the mounting screws. Place the wall plate up against the switch and install the wall plate screws.
Turn the Power On and Test
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With the switch fully installed, turn the circuit breaker back on and test the switch. If the 3-way switch is not working as intended, reach out to a professional electrician to finish the job.
Cost to Wire a 3-Way Switch
The cost to install any type of light switch ranges from $60 to $300, with an average cost of $150. Even though 3-way switches are slightly pricier and more complicated to install than standard switches, they fall within the middle of this range. Expect to pay about $100 to $200 when wiring a 3-way switch.
DIY vs. Hiring a Pro
If you have the electrical skills to install a 3-way switch on your own, you will save on the labor costs of hiring an electrician—usually around $50 to $100 per hour. All you have to do is purchase the light switch receptacle and any required electrical tools you don’t already have. As a result, going the DIY route can cost as little as $5 to $20. However, 3-way switches are challenging to install for a layperson, which is why we recommend that most homeowners hire an experienced electrician to get the job done correctly and safely.
Frequently Asked Questions
It is possible to wire a 3-way switch incorrectly meaning the light may not turn on or off. The 3-way switch will not work as intended if the wires are not attached to the correct screw terminals. The hot wire should attach to the dark-colored screw terminal, and the two traveler wires should attach to the light-colored screw terminal.
If a light switch is off, it’s very unlikely to cause a fire. For a fire to start, the switch has to be on, activating an electrical current, and the wiring must be faulty. However, the malfunctioning light switch could cause an intermittent current to move across the electrical wire. This issue could become a fire hazard with another device connected to the wire. You should replace the bad light switch as soon as you notice it or call an electrician.
A correctly installed 3-way switch will not trip a breaker. If using a 3-way switch trips your circuit breaker, the ground wire might be touching something it should not be, there could be a short in the wiring, a wire could be loose, or the wrong wires are connected to the wrong locations on the switch. If you cannot easily see the problem, such as a loose wire, contact an electrician to fix the issue.
Yes, one wire is always hot on the 3-way switch, meaning it carries the electricity from the power source to the switch. If you have a 3-wire cable in your home, you have two hot wires, or line wires, coming from the power source. Typically, you’d connect the hot black wire from the power source to the traveler wire and the hot red wire from the power source to the first 3-way switch. For the second 3-way switch, you’d then connect the hot black traveler wire to the switch.
Derek is a contributing writer with more than five years of professional experience covering topics that include interior design, hardware, home appliances, and more. He finds lawn mowing, weed whacking, and stacking firewood among the utmost therapeutic tasks.
Derek is a contributing writer with more than five years of professional experience covering topics that include interior design, hardware, home appliances, and more. He finds lawn mowing, weed whacking, and stacking firewood among the utmost therapeutic tasks.
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