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Subject - troubleshooting underground circuit
sean What is the best way to locate a break in an underground 120 V. circuit? (the situation is 120v supplying an irrigation control panel in a roadway median -circuit is about 300ft long from source across roadway)
JimmyDee This is a copy of an e-mail I was requested to send and felt I should post it here because if one person had questions, someone else may have them also. Maybe someone else can give some more up-to-date information as well.
Jim
quote:
Its been a while and I don't remember exactally how but I remember the first time I used the tracer setup, no one trained me. Just read the instructions and went from there. You need to obtain the signal generator from somewhere. Power company, telephone co and gas co. use them all the time.
I think you disconnect the power from the line and inject the signal into the wire or wires. The receiver has a signal strength adjustment and usually a speaker or earphones. It has a very sensitive receiver part that you hold about 2" off the ground and it allows you to follow the line. The signal either stops or goes way down where the break is.
Only had this system fail once and I think that happened because the break shorted to another lead that was continuous and allowed the signal to go all the way to the load.
JimmyDee Best way I know is to buy, borrow or rent a signal injector system that puts a signal on the wire and it usually will stop where the break is. You trace the signal with a wand type receiver that you can follow the signal to the break. Works for me 95% of the time.
Jim
iwire The cable locater is definitely a way to go if you can get one.

You may also have luck with just running a snake into the raceway and marking it with tape when it stops going in.

Do the same from the other end and lay them out on the ground and you can pin down (more or less) the area you need to dig.

This works great if a machine is doing the digging and there are no asphalt costs to consider.

If you have to dig by hand or patch asphalt go and rent the tracer tool, it will be the the cheapest way.
aussiesparky Sean
A UK company called "RadioDetection" have a couple of units that would help you on this one. I believe they have agent's in the US.
It has an accuracy detecting cable breaks to approximately 3-6 ft.
I have seen them detect cables 8ft deep +- 4 inches.

Andrew