3-way with Two Circuits Help

I’m trying to install red series dimmers, but the wiring for these two switch boxes is confusing me quite a bit. I forgot to take a picture of the landing wires before I started messing with them. I spent several hours yesterday tracing wires. I tried to draw up what I found. There are hot wires from two different circuits involved. The entryway box had a switch for the porch light, a switch that didn’t control anything (the “?” wire on the diagram; probably a removed light fixture), a 3-way switch for the entryway light, and a 3-way switch for the landing light. The Landing box had a 3-way switch for the landing light and a 3-way switch for the entryway light. I don’t understand how you can have two 3-way switches with only two travelers. I thought that each 3-way switch needed two travelers. I’m unsure how to keep the two circuits separate with normal 3-way light switches. Since I don’t need the travelers, I can see some possible solutions repurposing the traveler wires. I leaning towards using the travelers to bring the landing and entryway load wires down to the entryway box. Anyone have a better suggestion or can you explain how this is wired with normal 3-eay switches? I’d love to learn and have the ability to put normal switches back in when we move. Any help would be great.


I don’t know if I can fully wrap my head around this but what’s being described here sounds very familiar. This might have been wired up as a “Chicago”, “Carter”, or other type of 3-way wiring that is against current code. Weird (and Illegal !) 3-way Switch | Mike Holt’s Forum

After some more research, I understand what’s going on. If it helps anyone in the future, these 3-ways were wired up as a “Chicago”/“Carter” three way. Hot and neutral were attached to the traveler terminals. See how in one of my photos some of the 3-way switch terminals are daisy chained. Those are the hot and neutral wires. One common terminal was connected to one wire at the fixture. The other common was connected to the other wire at the fixture. The carter system allows the switching of both the hot and neutral conductors. It was banned in 1923.

Also it seems like it is pretty common to have two different circuits powering the two different switch location. This is another, more problematic modern code violation. However, it was not the case with my switches. The two “traveler” wires I found carried the hot and neutral from one box to only the other set of 3-way switches in the second box. So the circuits were correctly separated in my case. So how am I going to wire up my new switches? I do not have the traveler wires to hook up a modern 3-way switch correctly, but I can use z-wave association (red series dimmers don’t support being a hard wired 3-way switch pair anyways). I will use the “traveler” wires to either patch the 3-way “load” wires into the entryway box, or patch the 3-way “neutral” wires into the landing box to keep the two circuits separate.