3-way switch: which one is common?

[Oumati Asami]

I have a three-way switch. The terminals are arranged in a top-down fashion. Which one is the common? Can I assume the middle one being the common? Any way to test?

[Ed Pawlowski]

Is one of the screws a different color or other marking? Like two brass and a black or silver? There is also the green ground, of course.

[Clare Snyder]

If you need to ask how to test you shoouldn't be anywhere close to it.

[trader_4]

The common terminal is connected to one terminal with the switch in one position and the other terminal with it in the opposite position.

[Oumati Asami]

Thanks for the info. So, the middle one makes sense. I'll check it with a multimeter later.

[TimR]

No, you can't judge by the physical position of the terminal. Different models do it differently.

(The first time I replaced a 3 way, I compared the new switch to the old one and swapped the wires the same way. Nope, that was wrong. On one switch the common was middle, on the other it was not.)

[Oumati Asami]

OK. Time to check it with a multimeter.