Installing a 3 way switch can be simple with this advice from Tim Carter of AsktheBuilder.com. He'll walk you through wiring ...
3 way switches, showing you which wires go where so you'll have no trouble with your 3 way switch wiring.
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Check it out, three-way switches. That is what we are talking about, wiring three-way switches. Hi, I am Tim Carter and first I want to let you know a little safety note.
We are working with high voltage electric, the same thing that you have in your own home. Whenever you work with electricity, make sure it is turned off. I do not want you get electrocuted.
Three-way switches can be found in many homes and they are very useful. They allow you to control a light or maybe several lights from two different locations but the problem is they look a lot different in a regular switch.
A three-way switch has got three screws. Count them, one, two and three plus the green grounding screw but this black screw right here, that is the really important one that we need to pay attention to.
A regular pole switch has just got two screws on it and the green grounding screw. You can see how it is very different from a three-way switch. That is where the trouble begins, that third wire can cause three way switches not to work properly if you put the wires on the wrong screws.
I have built this little demonstration of three-way switches in my garden shed so you can see how they work. You will never find two or three-way switches that is close together in real life but here is how they work.
Look down here, you will find this yellow wire. This is where the power comes in to the first three-way switch. Now, notice there is a white wire that is a little bit thicker that leaves this switch, goes over and drops down in to the second switch box and look what happens, out of that switch box is another yellow wire that goes up and feeds the light. That is the basic wiring diagram and the most simplistic way to wire a three-way switch.
Now, let me show you the types of wire that we used to do that. Here are the two wires that I am using today to wire these three-way switches. This is a very common cable that you find in your home. It has got three conductors in it. The white wire is the neutral, the black wire is the hot wire and of course, the bare copper is the ground but look at this one. This has four conductors. It has got the black, white bare copper but this extra red wire, this comes in really handy, when you are working with three-way switches. We are going to take these switches apart right now so I can show you how all of these wires work together to make the lights go on and off.
Look at this jumble of wires in here. I know you are confused but look how simple this really is. Remember, this yellow wire has got a black wire which is the hot, that is the one that is coming from your service panel. It has got a white wire, that is the neutral and of course, it has got the bare copper wire. And this white wire had the same three wires plus it had a red wire.
Now, look how they all actually hook up. The white wires, the neutral wires, they need to be just wired and knotted together because that is sending the neutral directly up to the light bulb. That is what you wanted to do. The only wires that need to connect to the three-way switch are the black wires and that red wire.
Now, the ground wire is same thing. The ground wires are just twisted together and of course, one of the wires attaches to the ground screw on the actual three-way switch, that means now, we are only left with three wires.
Now, look at this, here is that black screw on the three-way switch I was telling you about and this black wire actually is the hot wire that comes from the circuit breaker panel. It connects to the black screw and the black and red wires that are in this white wire that goes between the two-three-way switches, you can hook them to either one of the brass screws on the three-way switch. It does not make any difference at all.
Now, let us go look at the other switch so we can see how that one is wired. Okay, here is the second three-way switch. I am going to pull it apart and I am going to show you the wires in this one and you are going to find out something very amazing. It looks identical to the first three-way switch.
Check this out, here are the two black wires and the red wire and of course the grounding wires and then back in here are the other two neutrals that were wired and knotted together. So, what is happening? We have got power that is eventually going to come in through this white wire and it is going to come in to either the red wire or the black wire and then it is going to leave the top of the switch through this black wire which is actually inside the yellow one and go right up to the light to make it work. It is that simple.
Let us look at this switch one more time. Okay, here is the second three-way switch. Notice here on the screw, here is one of the black wires and here is the red wire that is going through this white wire back to the three-way switch. Here is the black screw or the common and that black wire goes up to the white through the yellow wire. Here, of course, is our two neutrals that are wired and knotted together and of course the ground screw and the ground wire are connected together right here at the bottom of the switch.
You probably feel like a master electrician now that you have understood three-way swithces. Remember, keep the power off at your home. Let us summarize very quickly. The black screw on the three-way switches only connect the wire from the panel, the hot wire to it or the wire that goes up to the light. The other two brass screws, you have the travellers to it. Those were the black and the red wire in my example or in your case, it just might be two black wires in your electric boxes.