Im currently trying to upgrade two three-way light switches in the kitchen to some new smart three-way switches. The issue I have run into though is that there appears to be two common wires on one of the switches? The other switch has just one common but this one appears to have two. See picture below.
Picture shows the old switch with the wires already disconnected.
Any idea which one is which here? I believe the two wires on top are the traveler wires but not sure about the bottom two.
Best Answer
Notice how the two terminals are brass? Those are travelers. You'll save yourself a world of confusion if you get a 5-color pack of electrical tape and mark the traveler wires yellow. Every 3-way switch circuit is different. Colors are totally inconsistent in 3-way switches, the next one you see might have red and white travelers.
It's not unusual to have 2 wires on the common terminal; that is simply the supply being split off to also supply something else. That is more clear if it uses a pigtail, and feel free to convert it to a pigtail if you prefer.
You have to be especially careful with smart-switch 3-ways. Every 3-way switch configuration is different. There are many cases where the smart switch is not going to work in that box or even that application. Move slowly, document carefully, and if you get stuck on one, ask us a question and post pictures of what's going on inside both switch boxes.