I am working in my unfinished, detached garage (North American wiring). It has two 110/120 volts, neutral, and ground coming into a mains breaker and then to breaker box for the garage.
I have two sets of ceiling lights, each set has two sockets for standard bulbs. I wanted to, and have removed the wiring from between the breaker box and one set, and had planned to join that set to the first set so I had 4 light sockets on a single breaker. The breaker is 20 amp and is currently connected with armored and rubber sheathed wire. I think 12/3 or 14/3 but only one of the hot wires is actually hot and the other one you can see, for all circuits is cut and coiled inside the breaker box when you take the breaker box panel off.
The problem I am having is that right now I have one set of lights, two ceiling sockets that are connected to each other. They are not connected to any circuit anymore or anything else. My chirper (non-contact voltage tester) is giving me chirping / lighting on the ground wire. This wire only connects two disconnected lights. I am getting the same alerts on rubber coated armored sheath of the 12/3 / 14/3. I am also getting this on the studded metal plates that connect the wood joists. Ironically I'm getting this from wood itself. This aside from the armored wire, this seems contained to a 4'x 4' area of the ceiling joists. It also seems to be inconsistent in that sometimes it lights constantly but sometimes it doesn't.
I can't find the cause of this problem and I am concerned to work on these wires or outlets now. I have tried turning off different circuit breakers to find the cause but it seems like it's not any one circuit and circuits that are nowhere near that area still trigger it.
To sum this up, I have two light sockets that disconnected from everything but each other so there is no current and I am getting alerts on the ground, the junction box, the armored wire interconnecting them, the studded metal plates holding wood joists together and the from wood itself and I can't find the cause.
I have traced and tested everything in that area. I would bet there is no mystery wire I have missed and it's an unfinished ceiling so it's very easy to see all wires. I'm stumped.
Looking forward to replies.