How to Wire a Single-Pole Light Switch

By
Timothy Thiele
Timothy Thiele

Timothy Thiele has an associate degree in electronics and is an IBEW Local #176 Union Electrician with over 30 years of experience in residential, commercial, and industrial wiring.

Learn more about The Spruce's Editorial Process
Updated on 05/11/24
Reviewed by
Larry Campbell
Larry Campbell
Reviewed by Larry Campbell
Larry Campbell is an electrical contractor with 36 years of experience in residential and light commercial electrical wiring. He worked as an electronic technician and later as an engineer for the IBM Corp. He is also a member of The Spruce Home Improvement Review Board.
Learn more about The Spruce's Review Board
Single pole switch turned on by hand

The Spruce / Kevin Norris

In This Article
Project Overview
  • Total Time: 15 - 30 mins
  • Yield: Wire a single-pole light switch
  • Skill Level: Beginner
  • Estimated Cost: $2 to $8

Single-pole light switch wiring is so straightforward that even homeowners with limited do-it-yourself experience will find it easy. A single-pole light switch is the kind where one switch controls one set of lights. Whatever the reason—failed switch, wiring problems, or a style upgrade—this project costs about $5 and takes about 20 minutes.

Before You Begin

Before wiring the new switch, identify the wiring configuration. Depending on the wiring, you may be unable to use a single-pole switch.

  • Single-pole switch: The most common type of switch found in the home, one switch controls one device. The device is usually a light but it could also be a set of lights, an outlet, or a garbage disposal.
  • Three-way switch: Two switches control one device. This switch is not covered in this guide. Three-way switches are most often used when you want to control a ceiling light fixture from two different wall locations,
  • Four-way switch: Three or more switches control one device. A four-way switch is used with three-way switches when you want to control lights (or another device) from three or more locations. Four-way switches also are not covered in this guide.

Identify a Single-Pole Switch

A single-pole switch has two screw terminals on the side of the switch. When the circuit is on, both terminals and their wires are hot or live. There may also be a green grounding screw. Older single-pole switches may not have a grounding screw.

Safety Considerations

Electrical repairs come with some risk of shock. Be careful about relying on the labels or circuit index inside your electrical panel. The circuit labels may be incorrect, so always check for power after shutting off a circuit.

3:21

Watch Now: 5 Main Types of Electrical Switches Explained

What You'll Need

Equipment / Tools

  • Screwdrivers
  • Non-contact voltage tester
  • Wire strippers (as needed)
  • Needle-nose pliers (as needed)

Materials

  • Single-pole light switch
  • Grounding pigtail wire (if needed)
  • Wire connector (if needed)

Instructions

Materials and tools to wire and install a single-pole switch

The Spruce / Kevin Norris

  1. Turn Off the Power

    Turn off the power to the switch circuit by switching off the circuit breaker in your home's service panel (breaker box). If your panel has fuses instead of breakers, unscrew the appropriate fuse and remove it from the panel.

    Power turned off through circuit breaker in service panel

    The Spruce / Kevin Norris

  2. Test for Power

    Remove the two screws on the switch cover plate, and carefully remove the cover plate. Use a non-contact voltage tester to test all of the wires in the switch box to confirm the power is off. Also, touch each of the switch's side screw terminals with the tester probe. If the tester lights up at any time, indicating the presence of voltage, return to the service panel and shut off the correct breaker; then retest the wires to confirm the power is off.

    Yellow non-contact voltage tester inserted into switch box

    The Spruce / Kevin Norris

  3. Remove the Old Switch

    Remove the two screws that hold the switch to the box. Carefully pull the switch from the box, and check it once more to be sure the power is off to the circuit feeding the switch.

    Old screws removed from switch box

    The Spruce / Kevin Norris

    Tip

    Dimmer switches have larger bodies, and they are connected to the circuit with wire leads and connectors rather than screw terminals.

  4. Inspect and Disconnect the Switch Wiring

    Note the switch wiring. You should find:

    • Two live wires: There should be one wire only under each screw terminal. The wires likely will be black but they might also be red.
    • White pass-through wire: If other white wires in the box are not connected to the switch, these are neutral circuit wires that pass through the box and should be left alone.

    Loosen each screw terminal and remove the circuit wire. If your switch is connected via push-in wire connectors on the back of the switch, you can release the wires by pushing a small nail or screwdriver into the release slot next to the push-in connection.

    Old switch wiring disconnected by loosening the screw terminal with screwdriver

    The Spruce / Kevin Norris

    Warning

    If a white wire is connected to the switch, it is a switch loop configuration, where the switch is the last device in the electrical circuit. In this instance, the white wire is being used as a hot wire, and it should be labeled with a tab of black or red electrical tape.

  5. Connect the New Single-Pole Switch

    Connect the green grounding screw on the switch to the circuit's bare copper or green grounding wires. If the circuit has just a single grounding wire, then it can be attached directly to the switch's grounding screw. If there are two grounding wires, then attach a grounding pigtail to the switch's grounding screw and join the pigtail to the circuit grounding wires with a wire connector. Pigtailing is also the method used to connect a metal electrical box to circuit grounding wires—a box pigtail isn't necessary with a plastic electrical box.

    Inspect the end of each hot circuit wire. It should have about 1/2 to 3/4 inch of bare wire at the end and should be formed into a hook-like loop. If the wire end is in poor condition, trim off the bare end; then strip about 3/4 inch of insulation, using wire strippers. Bend the end of each wire into a C-shaped loop and wrap it around a screw terminal on the switch in a clockwise direction. Tighten the screws down firmly.

    Tug on all connections to make sure they are tight.

    Ground and hot wires screwed into screw terminal of single-pole switch with screwdriver

    The Spruce / Kevin Norris

  6. Complete the Job

    Gently tuck the wires into the electrical box, then mount the switch to the box with its two mounting screws. Reinstall the switch cover plate. Restore power to the circuit by switching on the circuit breaker (or reinstalling the fuse). Test the switch for proper operation.

    Single-pole switch faceplate installed with screwdriver

    The Spruce / Kevin Norris

FAQ
  • Which color wire goes where on a light switch?

    Because the switch terminals are interchangeable, it doesn’t matter which wire you put on each light switch terminal.

  • How can you tell which wires are hot or neutral?

    Usually, wires coated in white plastic are neutral or grounding wires. The black wires are hot or live, and red wires are also hot. However, this can vary in some applications (e.g., a white wire can sometimes be hot).

  • What happens if you wire a light switch incorrectly?

    If you wire a light switch incorrectly, the light may not turn on or it might turn on but be dim. In other instances, the circuit breaker may flip off or the wires in the box may arc, creating sparks.

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