I have 3 plastic pipes in my backyard and one (two?) of them have 110V lines in them. All wires - hot, neutral and potentially ground are inside the pipe so I can't just use a clamp meter / current transformer. Image below, you can see two white PVC pipes and one grey PVC pipe.
Without destroying the outer PVC pipes, how can I determine which plastic pipes are carrying the real 110V circuits and which ones are just empty? I can turn on the hot tub at the end of the circuit to start/stop electricity. I also have basic tools like voltmeters and a clamp meter.