B*Cat ....
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Henry, as JGO has mentioned
reflectometry is the preferred method of location for a HR-type condition. The problem is identifying its location when the HR is miniscule.
The reflectometer (or, TDR as it's more commonly referred to amongst engineers), not only displays HR conditions on its screen, it also highlights poundage changes (where one cable is jointed to another of a different size). If you are lets say, 4Km from the Exchange, that's a lot of cable joints that could be mistaken for a HR fault.
The key to locating a miniscule HR is to apply an old-fashioned TDR to the circuit at the EU's end, and ring the circuit number using your mobile phone. The HR can usually be seen as a tiny 'peak' rising and falling. You have to have eyes like the proverbial toilet-rat to see these sometimes
The reason I mention an old-fashioned TDR should be used, is the newer JDSU (cant speak for the EXFO) meter mistakes the ringing AC voltage as dangerous voltage, and flashes that very message up on the TDR screen so nothing else can be viewed.
Cheers, and good luck with getting a decent engineer.