I measured a 3 way switch and I got two wires on 2 different screws
measuring 120 volts. I thought only one should be hot??? I'm in a
rush so I can't write a lot but if looking at the switch with screws
were like this
c where c is the black screw
I got voltage at "a" and "c" so I'm confused. I'll google later
if that will help me but does this make any sense? I will try to
explain more later as necessary. I may take the wires off the switch
and just measure from the wires rather than from the screws on the
switch, if that matters. I want to explain more but gotta run.
Well it's a 3-way (that is double-throw) switch. Which is the common
screw? If it's c, it will be connected to a or b at all times. So
ift's conneected to a, you'll have the same votage at a and c.
If you didn't know this, you should do some reading before you fiddle
with this stuff. About switches, electricity, voltage, etc.
They weren't miswired when he started, 3 threads ago. He's putting in
some kind of timer, but doesn't say if he's done that yet, or if he
rewired any of the switches t hat were there.
You will ALWAYS have 2 hots on a 3 way switch.
You have power in and power out. There is no "off" on a 3 way switch.
They are just wired that depending which way the switches are set
neither "ON" of each switch is connected to the load. Switching either
switch to the other position means ONE "ON" is connected to the load.
Based on what I read elsewhere (correct me if I'm wrong please) if I
measure the voltage at the switch screws with wires fasten to them, I
might get 2 hot wires but if I remove those wires and check the
voltage just at the wires, I will get one hot wire.
I agree if the switches are working.
If the switches work and the terminals at one end are X, Y, Z; X and Y
are hot. Flip the switch and Y and Z are hot. Then this is the switch
connected to power - Y connects to power (and is the "common" terminal)
and X and Z are "travelers" to the other switch.
With terminals T, U, W; T and U are hot and the light is on. Flip the
switch and T is hot and the light went out. U connects to the light (and
is the "common" terminal).
Or, more simply if the switches work - at one switch the "common"
terminal will be hot in either switch position. That is the hot feed wire.
One switch the "common" terminal will be hot only in the switch position
where the light is on. That terminal connects to the light.
If you really understand how 3-ways work it isn't real hard to diagnose
a problem without disconnecting all the wires. Disconnecting the wires
makes it easier.
(Then you run into a Carter circuit or California 3-way.....)
When I do commercial wiring with three way and four way switches, I use
blue and yellow wire for the travelers. It really freaks out some other
electricians. I know some electricians who are clueless when it comes to
installing three and four way switches. o_O
Do you mean with no wires connected to the switch? Yes.
But at the top you were talking about screws, not wires.
But the question you ask now is just a part of a whole, and if you
understood what you were doing, you could have answered the question
yourself. You should read austerity's url and study every wiring
situation until you understand each one of them, even if you're only
goin gto use one this time . And you should probably read more than
Micky, believe me, I read a lot before I even started this job and
thought I understood my 3 wire switch. Obviously I was wrong but as I
wrote here, I was also reading. I do owe a lot GRATITUDE for the
people here who were quick to help me. I will take your advice and
read austerity's url . Thank you.
I might add to my earlier reply that I'm sure glad I bought a
multitester when I did (a couple weeks ago) in preparation for this
job. I don't know how I could have done this job without it.
I'm still not done as I'm waiting for daylight before I mess with the
leg end of this 3 way switch to unwire it again and test just the
wires for voltage. I know I can do this job that's why I refuse to
hire an electrician as my wife keeps asking me. Besides, this job is
making me learn 3 way switches. I still need to wire up a timer on a
2 way switch but that's easy and I chose to do this 3 way first to
We are going to get this damn thing working yet,.....
Here's how it works, this ought to help you understand just how simple
the wiring really is,
On Sun, 26 Feb 2012 06:57:21 -0600, "Mr. Austerity" <"PrintMo.Money ">
Thanks !!!! Don't worry, I won't give up. Just glad I have a
multitester to simplify. I mean if I know which wire is hot, there
are only so many combinations before it has to work. Of course I'm
not trying to discount the idea of learning the theory of a 3 way
switch either. I want to learn the theory and with your help, others
and google, I know I will. Thanks again.
Trying to wire in a Intermatic ST01 timer on a 3 way circuit. I've
farted around 1/2 the day and still no luck even tho I could have
sworn I followed the instructions. My daughter said to me earlier
that the reason it didn't work is because the installer had a few
loose wires so I gave her the look. Anyway, that's what I'm
checking for now at the main (hot) end because I think the remote
(leg) end is tight. Keeping my fingers crossed.
Well, your daughter sounds like a wise woman. FYI, that timer doesn't
wire like a standard 3 way switch. When installing the timer itself, you
only need to know the common wire of the circuit. It gets attached to
the black wire of the timer. The other two wires of the circuit go to
the blue and red wires of the timer. This end of the circuit is done.
Now you need to install the jumper on the other switch. You need to
remove the common wire and one of the other wires from the switch, wire
nut them together along with the small jumper wire. Once the 3 wires are
connected together, you install the other end of the jumper on to the
common terminal of the switch. Note: you will only have two wires
connected to this switch. Now it should work.
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