I am in need of some help. I have one light source and may be turned on
or off in three locations but only two of the switches work. I replaced
the 3 way switch that was giving me the problem and no effect. Is it
possible for the other 3 way switch or the 4 way switch to be defective
causing the power to bypass that problem 3 way switch? All the wire
connections are tight. Any help is appreciated. TIA.
In my experience, in similar situations I find that it is the four way
switch at fault. Mechanically, it is a more complex switch to build and
consequently breaks down more frequently. When changing a three way switch
it is only necessary to identify the "common" terminal and wire. On a four
way you must identify the travelers coming from each three way switch as
well as the locations of the input and output terminals on the switch, which
vary from manufacturer to manufacturer
Like this, viewed in a fixed font?
----------/ /--/ /-----light----
120 V B---------D C--------F |
Suppose you could control the light with C/D and E/F, but this only worked
when A/B was in the A position, so you replaced A/B...
I don't think so, if I understand your question, but you might not see
any change after replacing A/B, if (say) there's a break in the wire 2"
from B, inside the insulation where you can't see it.
3-way: 1 screw top and 2 screws bottom. Continuity from top to 1
bottom in one position. Continuity from top to other bottom in other
anything else tells you you have a bad switch.
4 way: 2 screws top and two screws bottom. Top left should have
continuity with top right and bottom right at same switch position.
Bottom left should have continuity with bottom right and top right in other
anything else tells you you have a bad switch.
3-way switches have two terminals on one side, and one terminal on the other
side. The one by itself is the common terminal; the two together are the
travelers. In one switch position, there should be continuity between the
common terminal and one traveler; in the other switch position, there should
be continuity between the common and the other traveler.
Your description would have continuity between the two travelers in one switch
position, and between the common and one traveler in the other.
In one switch position, there should be continuity between top left and top
right, and between bottom left and bottom right.
In the other position, there should be continuity between top left and
*bottom* right, and between bottom left and *top* right.
Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt.
And who wants to leave buttprints in the sands of time?
I think with this little information, it' would be guesses and person
experiences are the only thing you will be getting back.
Personally, I would take a varible out of the equasion, and yank out
the 4-way, and wire-nut the travels together, and then tackle the 3
ways. If they work, hey it was the 4 way, if they don't check for a
faulty 3-way, or crossed travelers. Once the 3 ways are positivly not
part the problem, I would figure out how the 4 way was, wired wrong or
defective(continuity detectors help).
But this is me, I feel safe working around electrical systems, when
Remember, only allow qualified persons to work on your electrical
I had a problem similar to this on a house I bought. I finally figured out
that the wiring was really for a 3-way setting (with two switches), not
4-way (three switches). The third switch was totally useless, since if it
was off, the light would never come on using the two other switches. I ended
up removing the useless switch and just putting a blank faceplate on the
box, it wasn't really useful anyway.
It's possible, but that's not what's wrong. THe problem is that
one of those "tight" connections is in the wrong place.
when you say the middle switch (are you sure it's the middle one?)
doesn't work, do you mean that moving it doesn't cause the light
to change state, that in one position the light is always on,
that in one position the light is always off, or that the light
doesn't work at all when the switch is hooked up?
Locate the 4 way switch, the one with 4 terminals on the switch. The other 2
should be 3 way switches with 3 connections per switch. Remove the 4 way
switch then connect like colored wires together. See if the 3 way switches
work. If so you have a bad 4 way switch if not the new 3 way switches are
probably wired wrong. To correct safley remove the three way switches
leaving the wires exposed but not shorting to each other or anything after
energizing the circuit find the hot wire to ground at the switch boxes. This
will only be at one box. This is the common and connect it to the common
terminal on one of the 3 way switches. connect the other two wires to the
other 2 terminals now you can find a hot wire at the other 3 way switch
location. This will be one of the travellers. Throw the first 3 way switch
you installed and another wire at the second should become hot, this is the
other traveler. Connect them to the other 3 way switch as appropriate. F
this isnt working for you or you dont know what i am talking about get an
> I am in need of some help. I have one light source and may be turned on
> or off in three locations but only two of the switches work. I replaced
> the 3 way switch that was giving me the problem and no effect. Is it
> possible for the other 3 way switch or the 4 way switch to be defective
> causing the power to bypass that problem 3 way switch? All the wire
> connections are tight. Any help is appreciated. TIA.
If it worked at one time, there's probably a bad switch. But it's very
very easy to mis-wire 3 & 4 way switches. There's even a chance that
you wired the 3 way incorrectly. Google "4-way switch wiring diagram"
and look over what you have. Good luck.
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