when you're taking out one three-way switch and you're putting in a new
three-way switch how do you know which wires have to go to which screws and
how to not mess that up so that your switching works correctly or incorrectly
[Music]
all right so I had a helper ask me recently we were trimming out a house and they were
putting in devices and they took an older device out put a new one in and all of a
sudden the three-ways stopped working and we were switching on like a whole bunch of Lights
in a different room all of a sudden none of the wiring had changed but the device was different
so let me explain this a little bit I'm going to take these out and kind of show you foreign
so it's really important always when you're taking out a device to try to keep track of
which wires are going to which thing because it actually really is important in three ways
specifically we'll see in here oh there's a bunch of other stuff going on inside of
there we've got two blacks and a red so how do we know which one has to go on which screw
if you'll notice on the device we have a black screw and a gold screw and another gold screw
over here we also have the green for the ground that one's pretty easy to not mess up but if you
mix these two blacks up if you end up putting this is the hot side of our three-way so this
conductor is our incoming hot this black is just one of The Travelers and when you
switch this switch you're switching between one traveler to the other travel so if one of these
is energized when it's in one position and when you flip it then this black no longer
becomes energized and it moves to the red so these Travelers switch in between them
and that's how a three-way switch works so if you end up feeding the hot conductor in and
putting it on a gold screw then the black the other black that's feeding this is not going to
work you're not going to be able to get power to pass through or when you switch it since you're
on the the incoming hot is on a traveler it's only going to work in one position just pass
power through all the to the rest of the or to the next device down the line so it's crucial to make
sure that you get these right so first thing that we need to do is always go turn off power
so since we've got our power turned off I'm going to loosen up my screws
now you'll notice on some devices too that you just have a screw and there's hooks bent around
them and other ones have plates that you actually are tightening a plate down a lot
of the Decora devices have plates on them and these old toggle or standard devices
don't it's okay either way when they've got plates though I don't bend hooks on them
I just use that plate it's a pressure plate
all right so now I've got all my conductors off now the really important thing to keep straight
you'll notice I have a whole bunch of other conductors in here so that means for some reason
this is a junction box as well as three-ways so all of these other wire nuts you got to be
really careful don't take anything else apart this green right here that is going to stay how
it is that's going to go on the device we just need to make sure that we got four wires when
we're all said and done going on the four screws so if you're messing around in here and all of a
sudden you're like oh crap I just lost track of which black one was which you'll always be
able to tell which two The Travelers are because they both go in the same sheathing so even though
this neutral is kind of like tucked in front of this one I know that these two go into the same
12-3 sheathing so I know in this 12 3 these are my Travelers even if there's drywall here and I
can't see what's going on I know whatever two are coming in the same exact yellow sheathing in the
back that these are Travelers the one that's not the one that's coming from a different direction
this one might not be able to see very well but it's going down the bottom of the box so that's
a 12-2 so I know okay 12 2 is going to be a hot or a leg doesn't really matter either way a hot
and a leg are both going to go on this black the two Travelers are always going to go on the two
goals so that's how you can keep it straight so no matter what if oh I got all these messed
up and I'm like all right well it's time to put everything back now I know well at least this is
my different one and these are my two that are in the same sheathing as each other so now I can sit
and put all this stuff back together and know that everything's gonna work correctly [Music]
now I always like to put the one on the black screw first just so as I'm doing this I don't
mess it up again and you'll see me using my oh by the way the Travelers the two Travelers it doesn't
matter which one goes on which gold screw in here it's just making contact on one making contact on
the other it just switches back and forth so just whatever you get in the practice of doing I would
just always do it that way also you'll notice that I'm using my screw gun to tighten all these
down that's just for the time being I'm actually going to go through last with a screwdriver and
make sure that everything is really tight now if this device had tightening torques on it per coat
I would have to use a torquing screwdriver but a lot of these devices don't actually have torque
specs on them and code says specifically that if something has torque specs you have to install
it per manufacturer's instruction if there's nothing if there's a device that doesn't have
that in the instructions then technically you don't have to do anything to torque specs on it
[Music]
and as always when you're putting devices back in make sure that that ground conductor
does not touch this other terminal or else you're going to have a ground fault
not a short circuit a ground fault and a short circuit are two different things
a lot of people have looked like a black hits a ground wire and it goes boom they're like
oh just shorted out I mean it technically I guess they're not wrong because it's taking
a shortcut but anything that touches ground or any like hot that touches a piece of metal
that's grounded out they call that a ground fault short circuit is where you have like
two blacks two Hots that short each other out or like a black and a white that short each other
out it's how we distinguish the difference between a short circuit and a ground fault
all right so now that we got our device back in let's go turn our breaker back on
and
so that's it just make sure when you take things out you don't start taking wire nuts
apart like messing it up even more the less things you take apart the better and make sure
that whatever you took off you pay attention to which screw you're taking each thing off
and then if you do mess it up just always look and see what's coming out of what she
that your Travelers are always gold screws and your Travelers are always coming out of
the same sheeting there might be some weird three ways that you're going to come across
some dead end three-way stuff like that where some of the wiring is going to be different on
these but the majority of the time this is when you run into problems with three ways