We had a power short at $work this summer, with MUCH smaller wiring. They brought in an Astro van filled will equipment to do the same fault finding. Standing above the fault, as the Xcel lineman told me to, I could feel the ground move. It was an interesting experience.
That sounds amazing and terrifying, sort of like the engineering equivalent of the old soviet dentists' belief that they have to poke cavities and judge their location and severity by how badly the patient reacts.