I am working on installing a 3 way smart switch, but the wiring in my house has me very confused as to how they wired it. My house is only 2 years old.
I have a single box, with one 4 wire romex coming in (black, red, white, bare). I was assuming this is the add on switch due to having only one incoming wiring, however, when I used my multi meter to test, this has the live power coming into it (black wire). I’m not really sure how the circuit works like this?
In the second box, I have the same 4 wire romex coming in, however the black wire is hooked a bundle of wire, and isn’t used in this circuit. The red and white wires (travelers are used), and the black wire is connected to a 3 wire romex (white, black, bare), which I assume is going to the light fixtures. The white wire here appears to be used as a neutral and is connected to another bundle of wires.
From what I can tell, I have a line-switch switch load configuration, but they have used one run of 4 wire romex vs 2 runs of wires to complete this.
I realize the first box doesn’t have a common wire, however, I do have very easy access to an outlet on this circuit that I think I can get a common wire from.
Can anyone help me confirm if my review of the wiring configuration is correct?