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3 Way Switch Video

Safety tip:

Turn off the power or circuit breaker feeding the wiring you are working on. Avoid electrocution.

Three-way switches allow you to control a light or lights from two different locations. The 3-way switch has three screws plus the ground screw. That is one more than the standard light switch. The black screw is an important one. If the wired are connected to the wrong screw, the 3-way circuit will not work.

In this example, the power comes into the first 3-way switch through a yellow wire. From that switch, there is an older white wire that happens to be 12-gauge wire, that is a little thicker than the other wires, that goes to the other switch. From the second switch, there is a yellow wire that goes to the light fixture. That is the basic wiring for this circuit.

Modern codes now require the outer covering on cables to be different colors so inspectors can see quickly what gauge wire is being used on a job. I happened to have an older partial roll of 12/3 wg cable in my basement that was made before the outer covering was required to be yellow.

Normal electrical wiring consists on of three wires - black, white and bare (ground). Wire for a 3-way circuit requires four wires - black, white, ground and red. The incoming power wire (yellow in this example) has the three wires. Between the switches, there is a white cable with the four colored wires. The white from the yellow and white cables get connected to each other with a wire nut. The sends the neutral directly to the light bulb. The black wires and the red wire connect to the switches.

The two ground wires are connected together and then connected to the grounding screw on the first switch.

The black wire from the circuit breaker panel gets attached to the black screw on the 3-way switch. The black and red wires from the white cable running between the switches get connected to either of the two brass screws on the switch.

On the other end, the two white wires are wire nutted together. One of the black wires gets attached to the brass screw. The red wire, running between the switches, gets connected to the other brass screw. The black screw has the black (common) wire that runs up to the light through the yellow cable. The two grounds are connected together and then to the green ground screw on the switch.

To summarize, the black screw gets either the wire from the electrical panel or the wire going to the light. The brass screws get the travelers hooked to them. Those were the black and red in this example. Be safe.


6 Responses to 3 Way Switch Video

  1. What type of paint to use on concrete block foundation, and would you use a different one for inside and out? There is some moisture seepage, but it's minimal. Lastly, what temperature should this be done?

  2. Watched your 3-way switch video. Well done but one comment. I got confused when you referred to the white and yellow cables as white and yellow "wires". Otherwise great presentation on how it all works. Keep them coming.

  3. I enjoyed the video and was very informative. But it did not answer the question to my problem. In the wiring of my 3-way switches I have different wiring set-up. There are two red wires and one single black wire; the white wires are all bundled together with a wire plug. My son went about in replacing several wall switches. (unfortunately I was not present to see the way they were originally connected) This led to several fuse breakers in blowing out. Before I go with the process of replacing the breakers, I want to make sure the wires are connected correctly to the old switches as it appears he purchased the wrong (1 way ) switches and could have contributed to blowing the breakers. Any help would be appreciated.

  4. Tim, I think you meant to say in the last paragraph, “To summarize, the black SCREW...” not WIRE. But really nice video that makes wiring 3-way switches a breeze.

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