I like your thinking, but I wonder how they work with a break in the wire. I'd have to identify which wire is broken (hopefully, not all of them).
The systems use a transmitter.
On edit:
Lift hot, neutral and ground. Use Ohmmeter to make sure that none of the conductors are coming in contact with each other. Possible wear of insulation and two conductors could be touching. Of course if this was the case then the breaker would be tripping. But does not hurt to check.
Lift the hot (black) wire, Neutral (lift from the panel buss), and also same process for the ground wire. Should get a clean read all the way through for conductor that is intact. However, the conductor with the open then the signal will fade from the receiver. Then you will accomplish location of the cable and identify which leg of the circuit is open.
So it would be a two step process.
Transmitter to the breaker side (of course make sure breaker is in the off position) that feeds the cable and then trace it out and when signal is lost, the break is located.
Repeat process at the user end of the cable, outlet, smaller panel etc. Follow signal path again until signal is lost.
Should be able to ascertain direction of cable run and get a good approximate location of a cable break.
Then break out the sharp shooter and dig!
Regards
Sure hope it makes sense. if not let me know I can ramble confusion with the best....j/k