Locating broken underground electric wire.

Thanks

Bob

I had to call around to find a guy that could do the search work. Not everyone has the equipment.

Good luck with this one.

It partly depends on the short - is it cleanly burned in two? Is it copper or aluminum? Aluminum can just corrode out to powder and still show a slight connection, yet not carry a load.

Is the wire in conduit? If so, sometimes you can pull each separate strand from each end (depending on how long the line is and how far the break is from the end), you can just pull the wire out and then use it to measure back to the break.

Sometimes you can even do that with direct burial if it is muddy, but obviously you have be a lot closer to the break.

If you have moisture in the conduit, it can really throw a locator off (or at least it did on the one we tried last).

We"ve fought a lot of those over the years with miles of underground wire to sprinkler pivots and usually the problems are around areas that dinged the insulation - like where it comes up out of the ground for the disconnect boxes, where someone might have driven over the wire before it was installed, etc.. Has anything been digging anywhere along the line?

Rarely, it was just a random location out in the middle and we never knew what the cause was.

We"ve quit hiring anyone to put wire in for us, since it is so easy to ding it and the problem not show up for a few years.

A small crack in the insulation can let moisture on the aluminum and over time it will ruin the wire.

If you are showing a partial short, it may be related to moisture - then look towards the low spots - not always the low spot of the surface, but sometimes the low spot of the buried conduit - like if it goes under a road or another line.

One time, we partly found it by trying to put a load (480 volt three phase) back on the line (it promptly blew the fuse again), but we could smell the burnt insulation near a disconnect.

If you really have to resort to digging and don"t have any suspicions of where - dig in half, cut the wires and test both directions, then move to the bad half and do it again. It is a lot of work.

Horribly expensive. And it will only tell you the distance to the break, not the actual location.

I would try the spark plug method.

But if you are desparate and money is not a problem I found a company on line that rents TDRs and Cable Route Tracers (link below). You might also try professional radio installation companies (try finding a break on the cable going up a 1000' tower).

HTH

Cliff (VA)

• Protec Equipment

If it's not a clean break it gets more complicated. I'm doing one this morning that has degraded aluminum wire with one leg measuring only 53 volts. Blowing the fault with a welder would let me use a locator.

Instead, I'll be measuring ground voltages along the cable path by carefully sticking a long screwdriver into the ground. The voltage is relative to a wire attached to the source ground. Takes a long wire. When the voltage spikes, there's the fault.

Haven't tried this method but it was suggested by an electrician on another forum who claims great success. Using an oscilloscope or a dedicated device (forgotten the name) can tell you the distance to the fault, but neither was available here.

Good luck.

I had to find someone to do that a couple of summers ago. Out of 20 or 30 electricians and electrical contractors listed in the yellow pages of the Olympia, WA phone directory, 2 had the equipment to locate an underground break. I don't remember how much the electrician who came out told me the equipment cost, but it was thousands. It didn't work, either. Half the run between the transformer and the meter base panel was under blacktop and the equipment needed to have two probes pushed into the ground every few feet along the path of the conductors. We were able to determine that the break wasn't under lawn. That narrowed it down to within 125 ft.

I'd go with the spark plug wire and a.m. radio method if I had it to do again.

All the best, Stan