TimR
Mon, 22
Aug 2016 12:47:58 GMT in alt.home.repair, wrote:

So my second guess, you replaced one three way switch with what
you thought was an identical one. But it wasn't identical. The
traveler screw was in a different place. (This problem bit me the
last time I replaced a 3-way. The new one had three screws in
exactly the same places, but I failed to look closely and notice
the screw colors were different. So I connected it wrong the
first time.)

You can't really assume that just because the terminals appear to be
in the same place that they still represent the same things as on the
original switch. You should instead, be looking for the odd screw
out. The ones that look the same on a new switch will be the
travelers.

If you have a meter and/or ticker and don't mind initially checking
the circuit hot, you can find out which ones are the travelers using
one of the tools. Pretty easy. Useful in the event you weren't the
one who removed the original switch and forgot to mark the wires as
they did so. I'm notorious about using a small piece of white
electrical tape wrapped like a sticker so that I can write on it,
clearly IDing what the wire is for. it's a habit another electrician
taught me years ago. Good habit, imo.

Hey, just guessing. Normally wires don't swap themselves.

I like your guess work. Sounds about right.


--
MID:
Hmmm. I most certainly don't understand how I can access a copy of a
zip file but then not be able to unzip it so I can watch it. That
seems VERY clever!
http://al.howardknight.net/msgid.cgi?ID=145716711400