I'm replacing an duplex outlet in our kitchen and when I removed the outlet, I uncovered some surprises that have me baffled and concerned. There are two cables entering the box, one with three conductors plus ground, the other other with two conductors. Here's a crude diagram, with measured voltages:
All three wires were connected to the outlet via backstab terminals, but I wasn't smart enough to take note of which wire went where.
In a lot of ways, this looks to be wired like a split outlet, with one separate phase going to each plug. In that case, wire 2 (white) would be the common wire for both outlets, with Wire 1 and Wire 3 beings the two hot wires from different phases. BUT the original outlet is not split - both tabs are in place and a check with my DMM shows continuity between the respective plugs. So how this was wired is a total mystery.
One or both of these circuits also seem to connect downstream to a built in microwave which is no longer functional with the outlet removed, regardless of which breaker I throw. I really wish I'd taken a photo of the existing outlet with wiring intact before I removed it, but I didn't. Can anyone help me figure how this was wired?