Lights out- Three way switches

Home Inspector with NCW Home Inspections, LLC

Lights out- Three way switches. Wenatchee and Quincy WA Home Inspection services.

One thing I try to do during a home inspection is to test that the 3 (and 4 or 5) way light switches have been wired correctly, or should I say working correctly (I actually do not see the wiring).

It is not all that uncommon to find that someone has not performed this correctly, mainly in older homes.

                                     Light out on 3 way circuit  Wenatchee Home Inspection

This seems to be one of those items that can confuse many DIY’ers. It really is pretty simple but you must understand how the "3 way" circuit works.

Hold on Mr. Home Inspector, why are they called "3-way circuits" when I have only 2 switches?

Well friends this has a bit of history to it. This goes back to the days of yore, to the days of Mr. Edison when this new trade of electrician comes into being and one way they would bid the job is by “drop points”.  A drop point could be a switch, a junction or a load point etc... So a regular switch would have 1 switch and one load, or known as a “2 way” switch.  So then we add that second switch and now we have 2 switches and 1 load and the term “3 way” comes into play. Makes sense right?

In simple terms a 3-way circuit is a lighting circuit that allows a light fixture to be controlled by two wall switches in different locations. They do this by switching the hot wire (load) toward the light on two alternate wires called "travelers".  The heart of this circuit is the 3-way switches.

Now there are several ways to “skin the 3 way cat” but I will show the most common way.

3 way switch variations

                           3 way light circuit Quincy WA Home Inspection
As you can see in this illustration we have the hot wire (black) come into the first 3-Way switch then we have two travelers leaving the switch going to the next 3-Way switch then a single wire out to the light. The neutral (white) is spliced and travels independently to the light to complete the circuit.

What makes this more complicated for many is just where the light is placed in the wiring system but the principle is exactly the same.

There are also 4-way, 5-way, and 10-way circuits. These really are just the same except we place 4-way switches between the two 3-way switches in the circuit.

                                4 way light circuit Quincy WA Home Inspections

Now wasn’t that easy?

But in all reality if you do not understand how these systems work you are much better off hiring a professional. Electricity can kill or burn your home down.


“If you think it's expensive to hire a professional to do the job, wait until you hire an amateur.”

Red Adair

NCW Home Inspections, LLC  is a Licensed Washington State Home Inspection service located in Wenatchee Washington serving Chelan County, Douglas County, Kittitas County, Okanogan County and Grant County Washington and the cities of Wenatchee, Leavenworth, Cashmere, Oroville, Cle Elum, East Wenatchee, Quincy and many more…  

Your Wenatchee and Chelan Professional Real Estate, Home and Structural Pest Inspection Service                                               509-670-9572


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Fred Hernden, CMI
Superior Home Inspections - Greater Albuquerque Area - Albuquerque, NM
Albuquerque area Master Inspector

Don, nice job of explaning the 3 way. This is why you have to have a healthy respect for electricity and it's properties! Even something as simple as replacing a bad 3 way switch.

Feb 26, 2013 10:34 PM #1
Clint Mckie
Desert Sun Home, commercial Inspections - Carlsbad, NM
Desert Sun Home, Comm. Inspection 1-575-706-5586

Hi Donald,

There are so many of these switches that are wrong.

I had a bath the other day that used to have a exhaust vent with a light. It was still wired for the vent and light but the vent and light was removed when the home was flipped.

With the bath in the middle of the home, it needs to have a working vent. No way around that fact.

Have a great day in the Greater Wenatchee area.

Best, Clint McKie

Feb 26, 2013 10:38 PM #2
Steven Cook
No Longer Processing Mortgages. - Tacoma, WA

Don -- thanks for the very  useful information and illustration regarding the 3-way switch situation.  I hadn't heard of the ones higher than that.

Feb 27, 2013 03:46 AM #3
Jay Markanich
Jay Markanich Real Estate Inspections, LLC - Bristow, VA
Home Inspector - servicing all Northern Virginia

I had a three way just yesterday that only worked when one was in the up position!  I wish I had your diagram to show my clients during the inspection!  You gots the best diagrams.

Feb 27, 2013 08:04 PM #4
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Fred, Thanks. Even some of the simple things is beyond many ;)

Clint, So true.

Steven, Thank you. once you passed the 4 way it is the same configuration just adding more 4 way switches.

Jay, Pictures do tell a story.

Feb 27, 2013 09:29 PM #5
Charles Buell
Charles Buell Inspections Inc. - Seattle, WA
Seattle Home Inspector

Good post Don.  Most people can handle this installation until the light is "between" switches :)  I warn my client that in many cases all combinations may not be tested in the context of the home inspection.

Feb 27, 2013 10:12 PM #6
Fernando Herboso - Broker for Maxus Realty Group
Maxus Realty Group - Broker 301-246-0001 - Gaithersburg, MD
301-246-0001 Serving Maryland, DC and Northern VA

I must be one of the few here in the rain that could follow your charts. . 

but why will someone attempt at doing this on their own?

a weekend do it yourself-er bad paint job. .just looks bad

but  bad wiring on a 3-way switch could be a fire!

Feb 28, 2013 10:36 PM #7
Than Maynard
Coldwell Banker Heart of Oklahoma - Purcell, OK
Broker - Licensed to List & Sell - 405-990-8862

That is why they have to get an electrical license. They get trained and paid to figure that out.

Mar 01, 2013 12:34 AM #8
Donald Hester
NCW Home Inspections, LLC - Wenatchee, WA
NCW Home Inspections, LLC

Charlie, That does send people for a loop.

Fernando, That does apply to many things with the electrical system.

Than, Very true.

Mar 01, 2013 01:42 AM #9
James Quarello
JRV Home Inspection Services, LLC - Wallingford, CT
Connecticut Home Inspector

Your post was about electrical switches, here I was expecting some thing else ;)

Mar 02, 2013 08:48 PM #10
Russ Svatt

Great article thanks - I found some variations on the illustrations shown which matched my own wiring here:

Hope they are of help

Nov 13, 2014 04:53 AM #11
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Donald Hester

NCW Home Inspections, LLC
Home Inspection Services and Inspection Questions
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