All right! Welcome to another CircuitBread practicals where we kind of talk about the
intersection of electrical engineering and electrician work to make it so electrical
engineers aren't quite so embarrassingly bad at knowing what's going on with the wiring in
their house and hopefully be able to help people when they ask questions.
So that we'd like to talk about 3-way switches. So we've talked about the typical one-way, two-way
switch. I don't know, I just did a normal switch before and those are one of the simplest things
in the world. Now, 3-way switch is actually not that much more complicated if you understand the
concept behind it. So if you have a normal regular switch, what it is is it's basically just a single
pole single throw. So you have your power coming in and then it either is open or it's closed
and that's it. So you have one wire coming in, one wire going out and you just break the flow.
However, with a 3-way switch, you need a special 3-way switch for 3-way applications and the only
difference is this is a single-pole double throw. So, instead of just being open closed, you have
two things where you're switching from one line to the other and you can actually see that on
the back. With the other normal switches, you basically have your ground and then in and out,
or in and out whatever and that's it. However with this one, you have two outputs and so on this we
have our common and on this, this is where you'd get your power in and then you have two wires
going out. So for a 3-way switch application, you actually need to use a special wire. You can't
just use your normal 12-2 or 14-2, you need to use 12-3 or 14-3. If you've watched our ampacity video
and we've talked about those wires you'd know that the difference is that with the
14-3, you get three conductors and with that third conductor, basically you're making it so that your
neutral is still tied, everything's good, but then you have two wires that you're switching between.
So your normal application, the way you do this is you have power coming into your first box
and then from that first box you have that special 14-3 wire going to your other box and then from
there you just have your typical wire going up to the light so that it gets the electricity..
The basic idea is that you are choosing between your two lines and on your two 3-way switches
on both sides basically just decide, “Hey, are we going to be providing power on this line?” and if
both of them are connected to this top line then great you get power that way. But if they're both
connected to the bottom line the power goes that way. And then if they're switched
then nothing flows at all and that is really it. It's getting that power from the first box to the
second box and then if there's power between those two, it goes up to the light just like normal.
So with that, let's actually show how this is wired in here. So according to code, as far as
I know, that's actually my biggest weakness, you need to have a 3-way switch at the top and bottom
of every set of stairs so you can flip it on on the way up and flip it off on the way down that
sort of stuff. Personally, I hate 3-way switches so I would never use this if I weren't required
by code but here we are. So this is actually the box that is powering both our kitchen lights and
also the lights down in the basement and you can see, we've got the stair 3-way,
the kitchen 3-way, oh man, I'd forgotten that we've done that as a 3-way.
And then you can see we have our ground and we left two ground pigtails in this because we're
expecting to have two switches in here and then we also took the power in and made it so we have
two pigtails there but we tied all the neutrals together because that's all we need. Okay, so,
let's do the stairs and as you can see we have a red wire here and that red wire is something that
you get with your 14-3 in this case this is that third conductor and as I've mentioned in other
videos, red can indicate a lot of different things. Communication line and extra wire,
if you're doing a 240 volt system, this is how you get your different voltages. However, in this case
we are using it as the traveler wire. So on this, we are going to ignore this kitchen one because
we're not worried about that right now. We are going to connect the green to ground like normal.
We will have this incoming power connected to this incoming wire which is where the power is coming
in and then we will take our two outs to the other box with a 3-way switch and we will connect these
like this. So that, when we're switching, we will be switching between connecting this wire to this
or this wire to this and making it so that we have that functionality that we just discussed.
So with that, let's just do this really quick. But again the incoming power comes into this one
and then on these it doesn't really matter which one's which.
However, if you find like if you want it so that when both switches are down it's off
and it doesn't do that where it's only on when one is on or it's off when one is up
and the other one's down something like that, you can just come back and swap one of these
two to make it so that they're both connected to the appropriate line. So worst case scenario,
if you don't like the way your switch setup is, just jump into one of the boxes and go back and
swap them. Again, only do it on one side. If you swap it on both sides you are just going to be
doing the same exact thing. It's like those people like, “oh you need to turn
your life around 360 degrees”, like well, that doesn't quite work you need to just do 180.
Okay and that is it. So if you go over to the other side, so again power's coming into
this this is going over to the other 3-way switch. The other box, you do the same thing
but instead of having the power in going here, you have the power out to the light going here
and then your two wires are hooked up just like that. Other than that it's the exact same.
So again, one final time, we have our power in coming to here and the switch is switching between
these two outputs. This is called the traveler, this is called something else... I don't remember
what it is. It doesn't really matter electrically, the way we think about them, they're the exact
same and that's it. So 3-way switches, they're a lot more complicated than the other switches
but that doesn't mean that they're actually complicated. Once you understand the concept
behind it, you can come here troubleshoot if you have any problems really easily because there's
not that much going on. So hopefully this helps if you ever need to swap out a 3-way switch,
hopefully this makes it so you can do it with ease. If you like the video, give it a like,
please subscribe to our channel because we are hoping to get back to our electrical
engineering and electronics topics very very soon. We're very excited to get back into that.
Have a great day and we will see you in the next one.