FHB Logo Facebook LinkedIn Email Pinterest Twitter Instagram Plus Icon Close Icon Navigation Search Icon Navigation Search Icon Arrow Down Icon Video Guide Icon Article Guide Icon Modal Close Icon Guide Search Icon Skip to content
Subscribe
Log In
  • How-To
  • Design
  • Tools & Materials
  • Videos
  • Blogs
  • Forum
  • Magazine
  • Members
  • FHB House
  • Podcast
Log In

Fine Homebuilding Project Guides

Wiring

Guide Home
  • Working with Electricity
  • Tools and Materials
  • Receptacles and Switches
  • Lights and Fans
  • Rough-In
  • Outdoor Wiring
  • Panels and Subpanels
How-To

Add to an Existing Three-Way Circuit

As long as the circuit can handle the extra load, run a two-wire cable to the new light, connected in parallel with the existing light.

Issue 210

Q:

I want to add a second light in a long hallway. The existing light is in between a pair of three-way switches. What’s the best and easiest way for me to add a light in this scenario?

Greg Lowe, via email, None

A:

Brian Walo, a licensed electrician in Mt. Pleasant, S.C., replies: In this scenario, it’s probably easiest (and least confusing) to run a two-wire cable to the new light, connected in parallel with the existing light. This is accomplished by twisting the hot, neutral, and ground (from the two-wire cable) for the new light together with the existing light. However, you have to be careful that you’re not overcrowding the work box that holds the original light fixture by adding another wire to the setup, and that the circuit has the capacity to handle the extra load.

Most plastic work boxes have their capacity and the maximum number of conductors written on the side, but this may be tougher to figure out for existing boxes. The calculation for the maximum number of conductors in a work box depends on the volume of the box in cubic inches. If you’re at or near the maximum number of conductors allowed, you may need to install a bigger box.

Sign up for eletters today and get the latest how-to from Fine Homebuilding, plus special offers.

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters
Previous: Adding an Electrical Outlet to an Existing Run Next: How to Splice Wires

Guide

Wiring

Chapter

Rough-In

View Comments

  1. T Dawg | Feb 25, 2018 05:58pm | #1

    I have a similar situation, however, I am not able to reach the center light to wire the additional light. I there a way to add a light to the circuit through the switch on the right?

Log in or create an account to post a comment.

Sign up Log in

Become a member and get full access to FineHomebuilding.com

Wiring

Wiring

Trusted, code-compliant guidance from the pros for working safely on any wiring project

View Project Guide

View All Project Guides »

Become a member and get unlimited site access, including the Wiring Project Guide.

Start Free Trial

Working with Electricity
  • Basics
  • Safety
  • Troubleshooting and Upgrades
Tools and Materials
  • Electrical Tools
  • Electrical Boxes
  • Cables and Wires
Receptacles and Switches
  • Materials
  • Wiring Receptacles
  • Wiring Switches
Lights and Fans
  • Lighting Design
  • Installing Lights
  • Fans
Rough-In
  • Planning
  • Installing Electrical Boxes
  • Running Cable
  • Retrofit Work
  • Making Connections in Boxes
  • Electrical Conduit
Outdoor Wiring
  • Basics
  • Outlets
  • Installing Lighting
Panels and Subpanels
  • Understanding Panels
  • Circuits
  • Installing a Subpanel

Fine Homebuilding

Follow

  • twitter
  • facebook
  • instagram
  • pinterest

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Membership & Magazine

  • Online Archive
  • Start Free Trial
  • Magazine Subscription
  • Magazine Renewal
  • Gift a Subscription
  • Customer Support
  • Privacy Preferences

Taunton Network

  • Green Building Advisor
  • Fine Woodworking
  • Fine Gardening
  • Threads
  • About
  • Contact
  • Advertise
  • Careers
  • Copyright
  • Terms of Use
  • Site Map
  • Do not sell or share my information
  • Privacy Policy
  • Accessibility
  • California Privacy Rights

© 2023 The Taunton Press, Inc. All rights reserved.

X
X
This is a dialog window which overlays the main content of the page. The modal window is a 'site map' of the most critical areas of the site. Pressing the Escape (ESC) button will close the modal and bring you back to where you were on the page.

Main Menu

  • How-To
  • Design
  • Tools & Materials
  • Video
  • Blogs
  • Forum
  • Reader Projects
  • Magazine
  • Members
  • FHB House

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Podcasts

  • FHB Podcast
  • ProTalk

Webinars

  • Upcoming and On-Demand

Popular Topics

  • Kitchens
  • Business
  • Bedrooms
  • Roofs
  • Architecture and Design
  • Green Building
  • Decks
  • Framing
  • Safety
  • Remodeling
  • Bathrooms
  • Windows
  • Tilework
  • Ceilings
  • HVAC

Magazine

  • Current Issue
  • Past Issues
  • Magazine Index
  • Subscribe
  • Online Archive
  • Author Guidelines

All Access

  • Member Home
  • Start Free Trial
  • Gift Membership

Shop the Store

  • Books
  • DVDs
  • Taunton Workshops

More

  • FHB Ambassadors
  • Reader Projects
  • Podcast
  • FHB House
  • Customer Support

Account

  • Log In
  • Join

Newsletter

Get home building tips, offers, and expert advice in your inbox

Signing you up...

This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
See all newsletters
See all newsletters

Follow

  • twitter
  • facebook
  • instagram
  • pinterest

Join All Access

Become a member and get instant access to thousands of videos, how-tos, tool reviews, and design features.

Start Your Free Trial

Subscribe

FHB Magazine

Start your subscription today and save up to 70%

Subscribe

We hope you’ve enjoyed your free articles. To keep reading, become a member today.

Get complete site access to expert advice, how-to videos, Code Check, and more, plus the print magazine.

Start your FREE trial

Already a member? Log in