I have often heard the term "crossed travelers" for explanations as to why 2 3ways won't work properly. I learned through trial and error that as long as the"common" connections were correct that it would always work no matter if the travelers were"crossed". Worked for a sparky once that insisted that wires be attached the same on both ends of the 3way "or it won't work"Does anyone know where this term originated?

Crossed travelers;
Heard that expression for years, and your right, guess what was meant was traveler crossed with common screw.

Had this a few months back when I did a complete rewire on a neighbor's house. The guy doing the plastering came along and had to temporarily remove one of my 3-ways, then he put it back with the common and one traveler swapped over. The circuit had a 4-way in it as well, and he tried to convince my neighbor that you couldn't have it wired so that all three switches could turn on the light no matter what the position of the other two switches.

You should've seen the look on his face when I swapped out the two wires and it all worked as intended.

The only thing that crossing the two travelers does is affect which way the switches have to be for on/off, e.g. whether both switches the same way=on and one up, one down=off or vice versa.

I've found that some people are quite picky about this! Do you always try to wire so that both switches down=off, or do you just connect the travelers randomly?

The up or down has not been an issue so far. But I suspect if you ran across the right customer it could be!

This actually was part of the Parade magazine that comes with the local Sunday paper. There was a question in the Ask Marilyn column, where people write in for the highly insightful and deeply intellectual responses, about 3-way switches and why the get mixed up after a while. (No link available yet...)