House built in the early 70's. Yesterday, I had to unmount a few light fixtures in my hall. The three lights are all controlled (as a single group) by three different wall switches. The fixtures are newer vintage and the bases are very lightweight, so I left them hanging by their electrical leads connected to wire nuts. One of them was not well connected to the wire nuts, and the black leads pulled out. The white ones remained connected and supported the weight.
When I went to connect the fixture and remount it, I noticed an extra black wire coming from the box. I assumed it went with the other black fixture leads in the wire nut. I had the breaker switched off so I was surprised to get a zap from one of the mounting screws when trying to work with the wires. I also noticed that when the "extra" black wire was connected to the fixture, the light bulb flickered dimly. I moved the extra wire aside and connected the light fixture to the other black lead (the one still in the wire nut). Flipped the breaker on and all the lights works fine. After that, I noticed another wire nut and bundle of black wires up in the box (picture below). Can anyone tell me if the extra wire belongs there? I really appreciate any help anyone can provide.