You have 4 possible combinations for the positions of the 2 switch
toggles: up-down, down-up, up-up, down-down. Only one of those
possibilities will get the light (or receptacle) to work. That's your
Referring to this page you should have already seen (you need Flash
Player to view the animation):
See the black and red wire going from switch to switch? Those are
called travellers. Even if things are wired correctly, if either
traveller is broken somewhere, the light (or receptacle) will work only
when both switches are in a certain position, one of the four
combinations listed above. It works when it sends current through the
*unbroken* wire. If a contact which connects to either traveller is bad
in either switch, same symptom.
If the wire going to the light (receptacle) is broken, it won't work
whatever combination the toggles are in. Realistically, if you can't
see why all of this is so, you will have a hard time diagnosing or
repairing any further.
You need two three-way switches. These switches don't have an "ON"
engraved on them, and if yours does have this you will need to replace
it. If both switches do not have the "ON/OFF" then they are not wired
JK, this is one of the most difficult electrical configurations
possible. What makes this complicated is that there are 4 possible
ways in which this circuit is wired. Here is a link that shows you the
4 possible wiring diagrams (ignore the information on 'X10' systems.
Caution: ALWAYS SHUT OFF THE BREAKER/ FUSE FOR THE CIRCUIT , AND test
for voltage with either a voltmeter, tick-tester, or a neon tester
BEFORE you open up any electrical box
The circuit will only work correctly if BOTH of the switches are truly
'3-way' switches. When you look at the switch, a 3-way will have 3
screw terminals. Two terminals screws are the same color--these will
be for the 'traveller' wires (usually black and red, but not always),
the odd-colored terminal is for the common wire, (usually black or
white with back tape applied).
I suspect that either one of your switches has been replaced by a
regular switch instead of a '3-way', or the traveller wires have gotten
I can't tell your DIY ability from your post, JK. If you are not
comfortable and do not have a good understanding of electrical theory,
please call in an electrician.
If you want to tackle this yourself, buy a good book and do some
research, as was suggested above.
I would recommend you try reversing the black/red wires at one switch,
restore power and test both switches. If both switches do not control
the light, then reverse the wires back. Go to the other switch and
reverse the black/ red wires, and restore power/ test again.
If you still don't get this working, go to
http://www.selfhelpforums.com/forumdisplay.php?f and post your
question with the exact configuration of every wire at each switch and
In case thay URL doesn't work, try this one:
Although there are more than one way to "wire" the circuit, they are
electrically identical. In each case, the "hot" is connected to one or
the other "traveller" by the first 3-wat switch, and the 2nd switch
selects which traveller gets connected to the "switched hot," and
switched hot feeds the load (light bulb or receptacle). All that's
different is the placement of splices in each case depending on
physical location of the components.
In alt.home.repair on Wed, 02 Mar 2005 11:02:26 GMT Phisherman
BTW, I put in some lights and used the new NO and FFO switches. They
work pretty much the same as the others.
If emailing, please let me know whether
or not you are posting the same letter.
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