By 'two different circuits,' I mean 'two separate single-pole breakers'.
Here is a crude wiring diagram of the switches and electrical box in question:
- The red things are wire nuts.
- The black ovals (1-6) are knockouts.
- Circuit X:
- Switch A is a single-pole switch that controls 4 outdoor lights.
- Switch B is a 4-way switch that controls 2 ceiling light fixtures (along with 2 other switches).
- May also have 1 outdoor outlet, but I forgot to check.
- Circuit Y:
- Switch C is a 3-way switch that controls half of an outlet (along with 1 other switch).
- Also has 4.5 'always-on' outlets.
- The pink wires in the diagram are white in reality.
- The black connected to Switch A is the hot.
- The pink (white) wires never measure a voltage, regardless of any switch's state.
- I have a very basic 2-probe voltage tester (like this), but no continuity tester.
- Everything functions correctly.
What is the easiest way to figure out:
- If the pink (white) wires are indeed neutrals?
- If they are associated with Circuit X or Circuit Y?
- What the orange wire is? (Possibly neutral for the other circuit?)