[SEL] OT! Electrical troubleshoting

[WurliTzerPgh at aol.com]

Maybe someone else has suggested this by now - I haven't read all the  
responses.  Have you tried using a TDR to locate the problem?  That's  short for 
Time Domain Reflectometer.  You connect it to one end and the  readout 
indicates distance along the wire to places where the cables  "characteristic 
impedance" changes.  It will find open circuits, short  circuits, low 
resistance connections and even places where the conductors are  nicked or squeezed. 
 Its an expensive piece of equipment but probably can  be rented someplace 
that rents such stuff.  It works best on coax cable but  I've used it 
successfully on many types of wires.
Jay
 
 
In a message dated 10/28/2010 08:23:00 Eastern Daylight Time,  
curt at rustyiron.com writes:

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


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