How do you Wire 3-Way switches?

Maybe you are new to electrical work and wish to wire a 3-way switch.

Wiring a multi-way circuit is harder than a single pole. It is the interconnection of two or more switches.

Three-way switches are useful in hallways and large rooms as you can toggle ON/OFF the lights from both ends.

But unlike single-pole wiring, installing a 3-way switch is harder. It has more screw terminals and thus requires more wires.

Diagram of a three-way wall switch

  • The common
  • Two traveller terminals
  • Ground or Earth terminal.

How the 3-way wiring system works

A three-way switch toggles ON and OFF the light fixture like other switches. But they do this from two ends.

When the toggles from both ends are up or down, the circuit is complete and the light will be ON. When the toggles are opposite, the circuit is open and there will be no light. This allows any of the light switches to power ON/OFF the light.

Tools and materials required for the wiring

They include:

  • Four in one screwdriver
  • Wire stripper
  • Plier
  • Voltage tester
  • Electrical tape
  • Utility knife

Materials required

  • Three-way switches (2)
  • 14-3 or 12-3 Romex cable.
  • Electrical boxes.

Note: Before any electrical installation, ensure that you power off the circuit breaker and also wear your protective glove to prevent electric shock and other hazards.

How to Wire a 3-Way switch in 5 Steps

There are three methods, but all depend on whether the hot wire goes to the switch first or the light fixture.

Whichever way you prefer, installing a 3-way light is easy when you follow our switch wiring procedures.

Step 1: Turn off your circuit breaker

Locate the circuit breaker that controls the branch circuit you want to install the switches and turn them off.

This is to prevent electrocution and other hazards during the installation.

Step 2: Mount the electrical box

Locate the two places you want to mount your switch and install the metal boxes.

This may be at the entrance and inside of your room, the end of the hallways, staircase, or any place of your choice.

Step 3: Feed in your cables.

Feed in a lengthy 14-3 NM Romex cable, or 12-3h if you are connecting to a 12 gauge wire. The 14-3 cable is a 14 gauge Romex wire with three insulated conductors, plus a ground wire. The three insulated conductors are black, red, and white, plus the earth wire.

Step 4: Connect the wires and switches

The 3-way switch comes with 4 terminals, the black or common terminal, two brass colour terminals, and the green earth terminal.

  • Connect the black (hot) wire from the line cable or power source to the black terminal of the switch
  • Join the white or neutral wire from the source to the white wire from the NM cable, using a wire nut
  • Also join the two brown wires together
  • Fix the earth cable on the metal box and connect it to the green terminal
  • Connect the black and red traveller wires from the NM cable to the brass terminals on the switch.

Moving to the second switch,

  • Join the two white wires
  • Join the two brown wires too
  • Connect the black wire that goes to the lamp holder to the black terminal of the switch
  • Fix the earth wire on the switch box and connect it to the green terminal
  • Connect the black and red traveller wires from switch one to the brass terminals of the second switch to complete the installation.

Step5: Install the lamp holder

Connect the black or hot wire from the second switch to one of the screw terminals, and the white or neutral wire to the second terminal, fix your bulb and test-run your project.

Three-Way Switch Wiring Diagrams

In this section, you will see some detailed diagrams on how to wire a 3-way switch

3-way wiring diagram when Power goes to the Light Fixture First

This diagram shows how you can wire a three-way light when the power is coming from the light fixture.

  • From the diagram, you can see that the power source enters the fixture box
  • The hot or black wire connects to the common terminal of the second dimmer.
  • Blue and red wires link the traveler terminals for both switches

We also connected the red wire to the common terminal of the first switch, which moves back to the light.

Three-way switch wiring diagram when power goes to the switch

This diagram shows a 3-way light control when the power enters from the switch.

  • From the diagram, you can see that we connected the incoming live wire to the common terminal of the first switch.
  • We then connected the traveling terminals of the two switches with black and red wires before connecting the second common terminal to the bulb.

Note: The neutral (white) wire from the supply moved to the bulb without branching to any switch.

3-way wiring diagram when Power goes to the junction box.

From the wiring diagram, the supply enters the junction box and connects to the common terminal of the right switch.

Two Romex cables with four wires and an earth cable joined at the junction box to connect the traveler terminal of the two switches and the bulb.

Difference between three-way switches and single poles

  • A single pole light switch has two terminals and a ground screw while a three-way switch has 3, plus a ground screw.
  • The toggle switch for a single-pole has ON and OFF while the 3-ways doesn’t have.
  • A single-pole switch controls a ceiling light from one location while the three-way control light from two different locations.
  • A single pole is good for small rooms with few light sources, while a multi-way switch is for large rooms and stairwells. 

That’s it for 3-way switch wiring. If you still need more information, watch our videos

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