3-Way Switch Wiring: A How to Comprehensive Guide

Here at the off grid cabin we’ve done our fair share of electrical work including 3-way switch wiring. We’ve done all the internal and external electrical wiring for the off grid cabin ourselves, including lights and switches, outlets, electrical panel, the solar system, connecting it to our electrical panel, as well as to the back-up generator. 

Image of The Off Grid Cabin Electrical Panel wired up

First and foremost, we’re no electrical experts. My background in electrical work comes from serving as a Naval Weapons Technician for ten years and being schooled at the Canadian Forces Naval Engineering School (electronics, hydraulics, mechanical and pneumatic systems) before becoming an Air Force Pilot. I feel know my way around electrical systems well enough to tackle wiring here at our off grid home. 

That being said, you can NEVER be too safe while working with electricity. If you aren’t comfortable call a qualified electrician. Electricity is invisible and unforgiving. Always follow proper safety protocols and check twice with a voltmeter or probe BEFORE touching anything.

Pinterest Pin Image of woman installing 3-way light switch with title how to install 3-way switches

Table of Contents

Introduction

Wiring a three-way switch may seem like a daunting task for some DIY enthusiasts, but fear not! 

In this guide, we’ll walk you through the process in a step-by-step manner with detailed diagrams to clarify depending on your existing wiring setup. 

Man installing 3-Way Switch Wiring

From understanding the basics of a three-way switch, to connecting the wiring, to ensuring it works properly. We’ll also recommend a couple YouTube videos that might simplify how these switches function.

Understanding the Basics

What is a Three-Way Switch?

A single pole switch controls a light from one location only. 

A three-way switch controls a light fixture from two different locations. 

Single Pole Light Switch vs 3-Way Light Switch

In the image above you can see a single pole switch has three screws while the 3-way switch has four screws. That’s for a “traveler wire” which is used in wiring 3-way switches. Another interesting note is that 3-way switches aren’t labeled “ON/OFF” like single pole switches.

It provides flexibility, convenience, and safety. We use a three-way switch to control the ceiling lights in the cabin loft. We can turn on the loft lights from a switch on the main floor, go up the ladder to the loft and then turn them off from a second switch upstairs.  

EngineeringEscape did a great job of explaining how a 3-way switch works. 

Here’s a short animation of how a 3-way switch works by Terry Peterman.

Tools You'll Need

Before diving into the wiring process, gather the necessary tools: 

Image of the tools for 3-way switch wiring laid out on table top

We also have a complete list of the tools we use here at the off grid cabin.

Step-by-Step 3-Way Switch Wiring Guide

Now, let’s dive into the actual process of wiring a three-way switch. 

Depending on which one gets the power first, the light switch (which is more usual) or the light fixture, you’ll follow one of the following diagrams for 3-way switch wiring.

Turn Off the Power

Safety first! Ensure the power is turned off at the breaker before you start working on the wiring. 

3 way switch wiring turning off circuit breaker

Always use a voltage tester to double-check and make certain the light switch has no power going to it.

Fluke VoltAlert Non-Contact Voltage Tester,

Identify the Wires

Differentiate the different wires in the 14-3 NM cable to avoid confusion. Typically, you’ll encounter three insulated wires (Black, Red, White) and a bare Copper ground wire.