On this same subject, fire alarm, data, intrusion wiring etc.is more often faulted because of the common practice of attaching to threaded rod, running in open ceilings and being damaged during installation. For years I spent much time going back after installation was supposedly complete and locating grounded cables in high rise buildings. (You cannot pull more conductors through a 4" pipe with a 1/2" rope after the initial install is done).
I found that TDR tracers were very helpful for distance. Also, using an analog meter like the Simpson 260 was also helpful to locate grounded wiring and estimate distance. By opening up the circuit and checking resistance to ground with the 260 I could figure out whic direction the fault lay in. Parking lot lighting could be similarly trouble shot using a megger set on 250 volt dc. Digital multimeters are harder to use for ground faults because they are sensitive to transient voltages.
