Need help identifying security wiring
The trade answer is a toner and probe, it is also the easiest.

An amazon search for ' telephone tracer ' will show a range of products I am talking about.

A toner is the tool that the phone company supplies to their employees that need to find a specific pair of wires in a cable, or inside a wall. Other places use them too.

The tool is art meets science if you are looking for 1 pair of wires in a bundle of 100, but if you are just looking for a cable, they are fairly easy.

This can also be used to find DEAD - NO POWER - outlets/breakers