Replace a Light Switch

You may need to replace or upgrade a light switch for a variety of reasons, such as if the switch becomes dirty, faulty, or outdated. You may also find it useful to replace old switches when preparing to sell your home or when trying to make your home more efficient. Upgrading a light switch is a great time to look into options such as dimmer, combination, occupancy sensing, and other types of switches for increased convenience, comfort, and efficiency. Learning how to replace a light switch is relatively easy and may be able to save you the cost of hiring an electrician.

Steps

Changing a Single-Pole Light Switch

  1. Purchase a new light switch that meets your requirements at a local home repair or hardware store. Tell the store employee what kind of switch you want and how many you’ll need, and they can help you determine the best purchase.
    • Single-pole switches are the simplest and most common. A single-pole switch has just two positions—“on” and “off.”
  2. Disconnect the power to the light switch at your home’s electrical service panel (also known as the breaker box or load center). It’s a steel box that may be located inside the house, in the basement, in the garage, or along one of the outside walls. You can either turn off the breaker that controls the lights in the specific room you are working on or turn off all the power to the house by switching off the main breaker.
  3. Test the switch. Flip the light switch on and off several times to be sure the power is off.
  4. Remove the switch plate cover. Using a flat-head screwdriver, turn the screws holding the plate in place counter-clockwise to loosen them.
  5. Unscrew the switch's mounting screws. Once the switch plate cover has been removed, use a flat-head screwdriver to remove the screws mounting the switch to the wall. Turn the screws counter-clockwise until they are freed from the wall.
  6. Remove the switch. Pull the switch away from the wall to expose the wiring, but leave the wires connected. Use a circuit or voltage tester to ensure no current is flowing.
    • If using a circuit tester, hold one probe of the circuit tester against the grounding wire (green or bare copper), and touch the other probe to each of the screw terminals (located along the sides of the switch).
    • If using a voltage tester, simply hold the tester near the wires.
    • If the tester registers any current, stop the project immediately until you’re able to power off the circuit.
  7. Pull out the switch. Pull the switch as far from the electrical box as the wires allow.
    • Take careful note of how the switch is wired. The wires will be connected to the switch by either screw terminals or push-in connectors.
    • Take a picture or draw a diagram so you can wire the new switch in the same way.
  8. Check the wires inside the wall box and identify each wire. Use a marker or colored tape to uniquely label each wire so you can tell them apart.
    • The box will contain one or two cables (or sets of wires). If the box contains two cables, it means the switch is in the middle of the circuit. You’ll see a total of six wires: two black (hot) wires, two green or bare copper (grounding) wires, and two (neutral) wires, which may be black, white, red, or any other color than green.
      • Mark the wire connected to the brass screw terminal or to the hole on the same side as the brass terminal as the “hot” wire.
      • Mark the wire connected to the silver screw terminal or to the hole on the same side as the silver terminal as the “neutral” wire.
      • Finally, mark the green or copper wire connected to the green screw terminal (on the other side of the switch from the brass and silver terminals) as the “grounding” wire.
    • If the box contains only a single cable (or single set of three wires), it means the switch is at the end of the circuit. You will see a black (hot) wire, a green or bare copper (grounding) wire, and a third (neutral) wire, which may be black, white, red, or any color other than green.
      • Mark the wire connected to the brass screw terminal or to the hole on the same side as the brass terminal as the “hot” wire.
      • Mark the wire connected to the silver screw terminal or to the hole on the same side as the silver terminal as the “neutral” wire.
      • Finally, mark the green or copper wire connected to the green screw terminal (on the other side of the switch from the brass and silver terminals) as the “grounding” wire.
  9. Disconnect the wires from the old switch. The switch may have either screw terminal connectors, which will be located along the side of the switch, or push-in connector holes, which will be located at the back of the switch.
    • If the switch has both screw terminals and push-in holes, most electricians recommend using the screw terminals for a more secure connection. But do not over-tighten; you may break the internal parts of the switch. If you tighten the terminals and hear a crack, discard the switch and use another.
    • If the wires are connected to screw terminals, turn each screw counter-clockwise with a screwdriver to loosen and slide the wire out with a pair of needle-nose pliers.
    • If the wires are connected to push-in connectors, the holes that the wires are pushed into will typically have a small slot beneath the hole. Insert a small screwdriver into the slot and push forward to release the wire.
  10. Begin connecting the wires to the new switch. Attach the black wire (hot) to the brass screw terminal. Either:
    • Use needle-nose pliers to wrap a little more than half of the bare wire clockwise around the screw and then tighten the screw clockwise to secure the wire.
    • Or push the wire into the push-in hole on the same side of the switch as the brass screw.
  11. Attach the white (neutral) wire to the silver screw terminal. Either:
    • Use needle-nose pliers to wrap a little more than half of the bare wire clockwise around the screw. Tighten the screw clockwise to secure the wire.
    • Or push the wire into the hole on the same side of the switch as the silver screw.
  12. Attach the copper (grounding) wire to the green screw terminal on the opposite side of the switch. Use needle-nose pliers to wrap a little more than half of the bare wire clockwise around the screw. Tighten the screw clockwise to secure the wire.
  13. Double-check that the switch is properly oriented. You should see the word “top” written on the switch indicating the side of the switch that should be vertically oriented toward the top.
  14. Carefully push the wires back into the box and then push the switch up against the edge of the box and tighten the mounting screws into place.
  15. Replace the switch plate and tighten the screws into place. Do not over tighten the switch plate, since it may crack under too much pressure.
  16. Return to the breaker box and turn the power to the light switch back on. Go back to the new switch and flip it on and off several times to ensure it’s in working order.

Changing a Three-Way Switch

  1. Make a written note or take a picture of how each wire is connected to the switch. A three-way switch allows you to control one appliance from two or more locations.
    • The switch may have either screw terminal connectors, which will be located along the side of the switch, or push-in connector holes, which will be located at the back of the switch.
  2. Identify and mark each wire. A three-way switch requires three wires: a hot wire, a neutral wire, and a traveler wire. The switch will also have a green or bare copper grounding wire. The box may contain one or two cables, or sets of wires.
    • Mark the wire connected to the colored screw terminal or to the hole on the same side as the colored screw terminal (it will typically be a dark color and will not be green) as the “common” wire.
    • Mark the two wires connected to the other two screw terminals as the “traveler” wires.
    • Mark the green or copper wire connected to the green screw terminal (on the other side of the switch) as the “grounding” wire.
  3. Disconnect the wires from the old switch.
    • If the wires are connected to screw terminals, turn each screw counter-clockwise with a screwdriver to loosen and slide the wire out with a pair of needle-nose pliers.
    • If the wires are connected to push-in connectors, the holes that the wires are pushed into will typically have a small slot beneath the hole. Insert a small screwdriver into the slot and push forward to release the wire.
  4. Connect the wires to the new switch.
    • Connect the black (common) wire to the common screw terminal, which you can identify because it will be a different color than the other two terminals (and not green).
    • If the box contains two cables or sets of wires, you will attach the traveler wires (typically black and red) to the remaining two screw terminals. Either: A) Use needle-nose pliers to wrap a little more than half of the bare wire clockwise around the screw and then tighten the screw clockwise to secure the wire. Or B) push the wire into the push-in hole on the same side of the switch as the colored screw.
    • If the box contains one cable or set of wires, you will attach the traveler wires (typically white and red) to the remaining two screw terminals. Either: A) Use needle-nose pliers to wrap a little more than half of the bare wire clockwise around the screw and then tighten the screw clockwise to secure the wire. Or B) push the wire into the push-in hole on the same side of the switch as the colored screw.
  5. Double-check that the switch is properly oriented. You should see the word “top” written on the switch indicating the side of the switch that should be vertically oriented toward the top.
  6. Carefully push the wires back into the box and then push the switch up against the edge of the box and tighten the mounting screws into place.
  7. Replace the switch plate and tighten the screws into place. Do not over tighten the switch plate, since it may crack under too much pressure.
  8. Return to the breaker box and turn the power to the light switch back on. Go back to the new switch and flip it on and off several times to ensure it’s in working order.

Changing a Dimmer Switch

  1. Mark each wire in the switch box. A dimmer switch allows you to control the brightness of a light fixture. Use a marker or colored tape to uniquely label each wire so you can tell them apart.
    • Mark the wire connected to the brass screw terminal or to the hole on the same side as the brass terminal as the “hot” wire.
    • Mark the wire connected to the silver screw terminal or to the hole on the same side as the silver terminal as the “neutral” wire.
    • Finally, mark the green or copper wire connected to the green screw terminal (on the other side of the switch from the brass and silver terminals) as the “grounding” wire.
  2. Disconnect the wires from the old switch. The switch may have either screw terminal connectors, which will be located along the side of the switch, or push-in connector holes, which will be located at the back of the switch.
    • If the wires are connected to screw terminals, turn each screw counter-clockwise with a screwdriver to loosen and slide the wire out with a pair of needle-nose pliers.
    • If the wires are connected to push-in connectors, the holes that the wires are pushed into will typically have a small slot beneath the hole. Insert a small screwdriver into the slot and push forward to release the wire.
  3. Connect the wires to the new switch. Most dimmer switches come with wires already attached. You will see two black lead wires and one green grounding wire.
    • Strip 1/2 inch of insulation from each to expose the wire.
    • Pair one of the black lead wires to the black hot wire in the switch box.
    • Pair the other black lead wire to the white neutral wire in the switch box.
    • Pair the green grounding wire with the bare or green grounding wire in the switch box.
    • Wrap the ends of the paired wires together and secure with a wire nut.
  4. Double-check that the switch is properly oriented. You should see the word “top” written on the switch indicating the side of the switch that should be vertically oriented toward the top.
  5. Carefully push the wires back into the box and then push the switch up against the edge of the box and tighten the mounting screws into place.
  6. Replace the switch plate and tighten the screws into place. Do not over tighten the switch plate, since it may crack under too much pressure.
  7. Return to the breaker box and turn the power to the light switch back on. Go back to the new switch and flip it on and off several times to ensure it’s in working order.



Tips

  • To help you remember where each wire goes, remove each wire and attach it to the new switch one at a time so you know exactly where it needs to go.
  • When you change out a light switch from the electrical box, be sure that the switch is straight vertically.
  • Wear rubber-soled shoes and use tools with rubber handles.
  • Older houses might not have a ground wire. If there isn’t a grounding wire in the box but the new switch ‘’’ does ‘’’ have one, cap it off with a wire nut.
  • If you need to expose more of any one of the switches wires in order to securely connect it, use a wire-stripper to strip away about 1/2 inch of the insulation that surrounds the wire.
  • If the switch won't work, your wiring may be faulty. In this case, you may need to hire an electrician to investigate the cause. In the meantime, keep the switch intact and turned off.
  • If the switch won't fit in the box, try trimming down the wires on the switch and using smaller wire nuts (can be found at a hardware store)
  • If you’re connecting the switch wires to screw terminals, you may find it easier to first use needle-nose pliers to twist the wire into a clockwise loop before hooking it around the screw terminal.
  • Cover screw terminals and bare wires with electrical tape for additional safety.

Warnings

  • Note that not all dimmer switches are compatible with CFL bulbs.
  • If at any point you feel unsafe or unsure how to proceed, call a professional electrician.
  • Handling electrical wires can be dangerous and risky (though mitigated when you shut the power off), so use all possible precautions and care when touching wires or switches.

Things You’ll Need

  • Flathead screwdriver
  • Phillips-head screwdriver
  • Circuit or voltage tester
  • Needle-nose pliers
  • Wire strippers (optional)
  • Marker or colored tape (optional)

Sources and Citations

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