3-Way Switch Wiring/ How to Wire Three-Way Light Switches.

A 3-way light switch wiring or multi-way switching allows you to control one ceiling light from two different locations. It is the interconnection of two or more switches.

A three-way switch helps in a hallway, and large rooms as you can toggle ON/OFF the lights from both ends.

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

Parts of a 3-way switch

A three-way light switch has four terminals

  • The common
  • Two traveller terminals
  • Grounding or Earthing terminal.

How a 3 or multiple light switch 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 switches to power ON/OFF the light.

Tools required to wire a three-way light switch

To wire a multi-way switch, you need these electrical tools.

  • 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 wiring or installation, ensure that you power off the circuit breaker and also wear your electrician glove to prevent electric shock and other hazards.

How to Wire a Three or Multiple Way Switch

There are three ways to wire a 3-way switch, all depending on whether the hot wire goes to the switch first or the light fixture.

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

Turn off the branch circuit from your electrical panel and add all the electrical boxes required.

Feed in a lengthy 14-3 NM Romex cable, or 12-3 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.

Connect the wires to the right terminals on the switch. The green screw is for earth wires, the two brass coloured screws are for travelers while the dark screw is the common terminal.

Ensure you wrap all the white wires used as travelers with black electrical tape for easy identification.

How to Wire a Three Way Switch when Power goes to the Light fixture first

This wiring diagram shows how you can wire a three-way light switch 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 second switch common terminal.
  • 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.

Wiring a three-way light switch when power first goes to the switch

This wiring diagram shows how to wire a 3-way light switch when the power goes to 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.

Three-way light switch diagram when light fixture is at the middle

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

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 a three-way light switch and a single pole

  • A single pole light switch has two terminals and a ground screw while a three-way switch 3, plus a ground screw.
  • The toggle switch of a single-pole has ON and OFF while a 3-way switch doesn’t have.
  • A single-pole switch controls a ceiling light from one location while a three-way switch controls it 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. 

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