I would like to know if it's possible for 'cross line' or contamination (don't know if it's the correct word) to exists in electrical systems just like in a telecommunication systems when one person phones the other person and one or both of these parties can sometimes hear the conversations of a third parties or unknown persons talking to each other through that same phone. In fact if you are one of the callers, you can talk to that stranger - it's like a line that has got mixed up.
If the above can happen in an electrical circuits:
a) How can we detect it in an electrical circuit?
b) Got any suggestion on how to solve the problem - can re-wiring solve the problem?

Would appreciate any good response, if any. Thank you.
Regards

Noise like from a fluorescent light could transfer from one wire to another in the same conduit or even NM running close together. It would only affect a sensitive device. There would be no real power transfer unless the wires were shorted together. You can sometimes measure a voltage in a wire next to a hot one, but any load will drop it. Shared neutrals can give strange readings too.

Sounds as if you are describing "crosstalk", weak signals induced onto a nearby conductor, acting as an antenna. Special test equipment usually is needed to detect these signals.

There may be more practical methods of detecting, however need an RF expert to assist with that. Being an electrician, I am stuck in 60 cycle mode.

Communication cables should be at least 2 inches away from power cables, ideally cross each other at 90 deg.