How to Wire a Light Switch

On This Page:

1. Wiring a Single Pole Switch
• Power to Switch
• Power to Lights
2. 3 Way Switch Wiring
3. Hiring a Contractor

If you enjoy doing the occasional project around the house, wiring a basic light switch is one of the simplest DIY wiring jobs to complete. Installation of a single pole light switch, which is just a plain light switch with no extras, is quite easy.

If you want to install a 3-way light switch, however, the job becomes a little more complicated. It can still be done, if you carefully label your wires and pay attention to detail. While many home DIY warriors choose to tackle the job on their own, a good number also decide that the $145 cost to professionally install a lightswitch is well worth the money.

Whichever light switch project you need done, if you are unsure or uncomfortable about handling a wiring project, the better course is to find an electrician near you that will ensure that the job is done correctly.

Steps for Wiring a Single Pole Light Switch

There are two basic wiring configurations for installation of a single pole light switch. For both configurations, you will need the following materials:

• Phillips screwdriver
• Utility knife
• Wire strippers
• Needle-nose pliers
• 15-amp light switch
• Wire nuts

Important: Before working with wiring of any sort, be sure to turn the power off at your electrical panel to ensure your safety.

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Configuration One: Power to the Switch

For the first configuration, the power comes to the switch and then goes to the light. In this case, you will see two black wires (hot), two white wires (neutral), and two bare copper wires (ground) coming from the box in your wall.

Note: If the box is newly installed, these wires may not yet be visible, and you may simply see two sheathed white or gray 14/2 wires coming from the wall. In this case, perform these extra steps to prepare the wires for installation of the switch:

1. Using a utility knife, score through the middle of your sheathing approximately 6 inches. Cut off sheathing and any brown paper you may find inside the sheathing. Once you have done that for both wires coming out of the box, you will see two black wires, two white wires, and two bare copper wires.
2. Using a wire stripper, strip off approximately ¾ inch off the tips of all the black and white wires.

Once this is completed, follow the steps below to proceed with installation of your light switch (or check out this diagram):

1. Locate an additional copper wire and combine it with the two copper wires by using your pliers to twist it into a “pigtail”. Once the copper wires are twisted together, apply a wire nut to the end securely.
2. Twist together the two white wires and cap them securely with a wire nut.
3. Use your needle-nose pliers to grip the end of one of your black wires. Twist the end 180 degrees, forming a nice, neat loop. Repeat with the other black wire.
4. Once your loops are created, attach one of the loops to the contact point on your light switch. Hook the loop around the contact point and tighten the screw in a clockwise manner. It is very important to ensure that the screw is extremely tight, because a loose connection can lead to an electrical fire.
5. Repeat the exact same process with the loop from your second black wire. Remember to ensure a tight connection.
6. You should now have a remaining loose bare copper wire. Use your needle-nose pliers to create a 180 degree loop at its end.
7. Hook the loop you just created around the green ground screw at the bottom of your light switch. Once again, remember to ensure that you have a tight connection.
8. Insert your light switch into the box and secure it with a screw at the top and bottom of your switch.
9. Turn on the power, and test your switch.

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Configuration Two: Power from the Lights

For the second configuration, the power comes from the light to the switch. This is the easiest configuration with which to work. If your box is configured in this way, you will see one black, one white, and one bare wire coming from the box.

Follow these simple steps to install your new light switch (or look at this diagram):

1. Hook the bare wire to the box and to the switch.
2. Hook the black wire to the bottom terminal on the switch.
3. Hook the white wire to the top terminal on the switch.
4. Push the switch into the box and secure it with screws at the top and bottom.
5. Turn on the power and test the switch.

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Steps for Wiring a 3-Way Light Switch

Installing a 3-way light switch is a much more involved process than installing a single pole light switch. However, it can be done with a little patience and attention to detail.

There are a number of configurations that can be used for wiring a 3-way switch. They are:

• Power to switch to switch to single light
• Power to switch to switch to light to light
• Power to switch to light to switch
• Power to switch to light to light to switch
• Power to light to switch to switch
• Power to light to light to switch to switch
• Power to light – splits to switch and to light – light to switch
• Power to light – splits to two 3-way switches
• Power to switch – splits to switch and light

If you find these configurations too difficult to picture, rest assured you are not alone. For many of these configurations, the best course is to hire a professional to install your 3-way switch to ensure everything is done safely and correctly.

However, one of these configurations, from switch to light to switch, is the most common type of 3-way light switch installation.  That configuration is the one that will be explained in detail here.

Important: Remember to cut all power coming from your panel box before beginning any wiring project.

In this configuration, you will have two boxes and a light fixture. Coming into the first box from your power source will be 14/2 wire, which has a black wire (hot), a white wire (neutral), and a bare copper wire (ground). Going out of both boxes and into your light fixture will be 14/3 wire, which has a black wire (hot), a white wire (neutral), a red wire (traveler), and a bare copper wire (ground).

1. Twist the two copper wires in the first box together and attach them to the ground nut on the switch.
2. Attach the black wire coming from the power source to the black nut on the bottom right of the switch. Secure tightly.
3. Attach the black wire coming from the light to the top right nut on the switch. Tighten securely.
4. Attach the red wire coming from the light to the top left nut on the switch. Tighten securely.
5. Twist the two white wires together and attach a wire nut.
6. At the light fixture, there is one bundle of wires coming from switch one, and one bundle coming from switch two. First, twist the two bare copper ground wires together.
7. Twist the two red wires together and attach a wire nut.
8. Take the white wire from switch two and twist it with the black wire from switch one. Mark the white wire with a piece of electrical tape to indicate that the wire is now a hot wire. Attach a wire nut.
9. Attach the black wire from switch two to a contact on the light fixture. Then, attach the white wire from switch one to a contact on the light fixture.
10. At the second switch box, attach the black wire from the light fixture to the black nut on the bottom right of the switch.
11. Attach the white wire from the light fixture, which is now the hot wire, to the nut at the top right of the switch.
12. Attach the red wire from the light fixture to the nut at the top left of the switch.
13. Connect the bare copper wire to the green nut at the bottom left of the switch.
14. Push both switches into their boxes and secure them with screws at top and bottom.
15. Turn on your power and test the switches.

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Hiring a Professional

If you are comfortable with tackling the job of installing light switches as a DIY project, you may realize significant savings by doing the job yourself. However, if you are unsure about how to handle any wiring project, the best course of action is to hire an electrician to do the job. If that is your choice, be certain to look for a licensed, bonded, and insured professional to ensure your project is done safely and correctly.

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3 Comments

1. kathleen mccarthy, July 13:

   This was very informative.
   But I cannot find a site that helps me with a wiring problem. I have a porcelain really old , actually there are 3 light switch’s on this plate. One is a 3 way. Each has a color wire differently connected. The new light switch and old ones are just not looking the same. help

2. ken, September 1:

   how do i rewire a three way switch with a red wire black wire and a white wire

3. ken, September 1:

   this switch is on a table lamp