[SEL] OT! Electrical troubleshoting

[curt at rustyiron.com]

Hey guys and gals,
Since the SEL is a vast pool of knowledge to draw from, I need help with
troubleshooting an underground wire at the new place. From the house is a
12 ga wire that goes underground a couple of hundred feet to feed a couple
of pole lights. This is that gray outdoor wire.
The lights quit working and after some troubleshooting was surprised to
learn the wire itself is bad. That's highly unusual as wire rarely goes
bad. After disconnecting at each end and using jumpers and a ohm meter, I
have determined the black wire is the one bad. The white (neutral) and
ground wires are both good.
Yesterday I had a fellow come over with a signal generator and tracer. We
hooked the signal to the black wire and the other to a grounding rod.
Strangely the signal went all the way to the pole light. This wire will
conduct the trace signal, but not a bit of current will pass. Perhaps the
wet dirt is creating a bridge for the break in the wire allowing the
signal to continue on past the break. We've had several inches of rain the
last days.
So, how do I identify where the break is w/o digging up the whole yard?
Is there a way to completely "burn" this wire at the bad place, so the
tracer signal can no longer pass across the bad place?

Looking forward to your creative ideas.
Curt Holland