On Monday, April 13, 2015 at 2:36:24 PM UTC-4, Leif Neland wrote:
The perimeter loop cable around my lawn for my automower is broken.

I have a cable fault detector with a tone generator and a "pen"
receiver, which can trace along the cable, but it doesn't work when the
single wire goes under ground or concrete.

I wonder if a network/telephone cable tester can work on a single wire
underground.

I'm looking at

http://www.ebay.co.uk/itm/Portable-N...r/181692076054

After all, a single wire in the ground should look a little like a
coaxial cable?

Leif

--
https://www.paradiss.dk
Ting til konen eller kæresten.
Eller begge.

I've used a signal generator to send a 600KHz modulated signal onto the powerline in my house to trace outside power lines 2 ft in the ground. I use a portable AM radio that I can point the iron core loop antenna vertically at the ground over the wire to null the signal so that the antenna points directly at the line. Just follow the line around until you lose the signal by swinging the radio back and forth listening for the null and the signal level. (If you can't get a good null reduce the signal generator level. The lower the better.) The signal should get weaker really fast as you pass the break. When you get past the break you will even be able to point the radio antenna back at an angle to "see" where the break is. I am assuming that you only energise the underground loop from one end and keep the other end as far as possible from the generator and the other line. I have also found a break in a power line for a barn this way so it should work for your purpose. Warning.... If the line has any voltage on it isolate the signal generator with a capacitor to protect the generator and yourself. Something like a .01 uf should work. It might be best to just put the capacitor in the circuit just in case there is a short that might put lethal voltages on the line.

....Bob