Bob F wrote:
....

Is the reflection going to be obvious? This is something I've never tried to
see.
....

Maybe, maybe not... (How's that for precision? )

Depends on many factors including the cable characteristics itself, the
type of fault, where the fault is located, the rise time and width of
the pulse, etc., etc., etc., ... It takes some skill and experience to
interpret the reflected waveform even w/ a "for purpose" instrument.

Here are a couple of links that have some decent description of some of
the basics. I've never tried TDR on anything except very high impedance
signal cable, so don't really have any idea of what it would look like
for ordinary wiring. My old Tek scope doesn't have fast-enough rise
time in the internal generator for anything of reasonable length so
don't have a way to see how it might look as compared to what I have
seen in the past, unfortunately.

http://www.tscm.com/riprcop.html
http://www.tscm.com/riwavef.html

If you've got some good quality test gear and a sample roll of romex you
could always give it a shot and see if you can figure out the length
of a couple of test sections.

Overall, though, I think either the "binary section" or "rent a locater"
methods will turn out to be more successful than homebrew TDR based on
the level of sophistication it takes in commercial instruments to make a
successful instrument. You might just get lucky though, so can't hurt
to try...

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