I was recently replacing two three way switches in a hallway. They were old, and also they were not working like three way switches. On the first switch I replaced I noted that the common wire was the black one. When I moved on to the second switch, the white wire was connected to the common terminal, so I guess that it explains why the old switches were not working properly. However, I wasn't which switch had it right, so on the new switches I tried connecting the black wire to the common terminal on both switches. It worked. For curiousity, I then tried it using the white wire on both common terminals. It worked also. Is this normal? I checked another three way circuit in my house that has always worked fine and found that it was wired with the black wire on the common terminals.
Answer:
When it comes to wiring three-way switches, if both switches work, don't question it - enjoy it.
