Hi arrie,
Just seen your post:
https://www.electro-tech-online.com/threads/testing-breakage-in-cable.40636/
This has happened to me many times. I use extension leads a lot, and they have a rough life
with me, i am sorry to say.
Over the years i have found a couple of simple ways to deal with this.
The first way is to cut the cable. Have a really good look at the ends near the fittings,
these are the most likely places for a break, with the bonus that if a bit of damage near the
end gets cut, and its not the break, then youve only lost a short bit. Sometimes its worth
cutting a foot from each end, if its important not to shorten the cable much, this will often
clear the problem with minimum effort. One end at a time of course.
If its still got the break, then my next cut would be part way along, not half way i would go
with about a third. This method as mentioned, gives you two cables, the down side is finding
extra plugs and sockets for the remaining good bits.
Another way i have used many times is the good old bell-set.
Just a little bell and battery, connect it to each end of your faulty conductor, and wiggle
the cable through your hands working your way along. Hopefully the bell will sound if you
wiggle the faulty bit and get it to conduct.
Another way i have used is a spark. Causing a spark at the break can be entertaining. Takes
a bit of setting up, one problem is trying to hear it. If your break is wide, you may not be
able to use this method. I have used a buzzer and battery with a transformer to locate a
break in the past by waiting for the smoke from the spark to come from the cable. That was not necessary really, as i had by then located the whereabouts of the break cos i could hear
the spark, but allowing it to continue until it burnt through led me precisely to the break.
Another possibility that i have not tried is capacitance.
It might be possible to approximate the length of a conductor by its capacitance to the
remaining conductors. Maybe a wheatsone bridge arrangement. Or just a simple oscillator like
a "stylophone".
Or maybe the capacitance could be used externally, to pick up a signal along the conductor ?
Which would fade past the break ?
Or maybe injecting RF might give an increased radiated signal at the open end, i dunno but
it sounds possible. Someone skilled with ariels might know about that.
Best of luck with your cable checks, lets us know how you get on,
Cheers, John