I was recently working on some wiring in my bathroom, and I noticed a 3rd load wire that I couldn't quite explain.
There were 4 Black Wires coming in (with 4 corresponding White Neutral wires). One of the Black wires was for the light, one was for the fan, one was the source (hot) wire, and there was a 4th one that I couldn't figure out.
What was really weird, is that the 4th wire seemed to be hooked directly to the source/hot wire. The entire setup was like this:
Switch 1 toggled fan Switch 2 toggled light Black/Hot/Middle -------> Top of switch 1 via Screw (middle of the wire was stripped, wrapped around screw and continued to switch 2) Black/Mystery/End ------> Top of switch 1 via Insert Black/Fan/End ----------> Bottom of switch 1 via Insert Black/Hot/End ----------> Top of switch 2 via Insert Black/Light/End --------> Bottom of switch 2 via Insert
If that list doesn't make sense, I can try and make a better diagram. Really I'm just trying to figure out what that last black wire was for, and why it was directly wired to the source line.
Thanks for any help/advice!