How to Wire a Three Way Switch with One Light

Here is some useful advice on how to wire a three-way switch with one light. Why do you need a three-way switch? Well, let’s suppose that you have a two story flat or a house. When you want to go upstairs to bed, on the stairs you have a switch that turns the light on the stairs or on the second floor so you can see your way up. When you get to the top of the stairs you have another switch that turns the same light off. So, the thing is that you can turn on/off the light from a different locations regardless of the position of other switch. Isn’t this convenient? This electrical installation is called a three-way switch.

How Does It Work?

Now let’s look at the three-way switch. It looks similar to a standard switch, but with one great difference – it has three terminals! Why? Well, one of the switches will be connected to source with one terminal called common and the other one will have this common terminal connected to a light. Next, this common terminal will be at all times connected to either of the two left terminals in one switch. Switches will be connected to each other by these other two terminals. In this way when you hit either switch you can turn the light of/on regardless to the other.


So, we have a source, two three way switches and a light bulb. The first thing you want to do is to make sure there’s no electric current in wires, so go to your fuse box and turn off the electricity. Check with your tester if you’ve done it right.

Now, your cable has 4 wires, right? The color of wires may vary from country to country so check your country’s standards. It should have, for example, black, red, blue and ground wire. Let’s say that the blue wire is a source, so this wire will be connected to a common terminal of one switch. Black and red wired will connect other two terminals between switches. The order is irrelevant as long as you don’t cross the wires. The ground wire will be connected to ground socket in the switch and will then lead to the light. The common terminal of the other switch will be connected to a light.  The finishing touch is the aligning of switches.

Make sure you have done everything right, go to a fuse box, and turn the electricity on. This three-way circuit is a very handy device that can make your life a little bit easier, try it and see the change.

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