Lights out- Three way switches.

Submitted by DonHester on Tue, 02/26/2013 - 09:11.

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.

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…

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www.ncwhomeinspections.com 509-670-9572

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Lights out- Three way switches.