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Thread: Break in underground wire
08-09-2010, 04:06 PM #1
Break in underground wire
Is there an easy way to find a break in underground wire? Meter is mounted on garage and then house is serviced from it underground, one leg is dead, aluminum wire 3 or 4 gage
08-09-2010, 04:25 PM #2
If the wire is completely broken, an underground wire tracer such as a Cable Hound will work. You will loose signal after the break. If the wire burned under load, I don't know whether the Cable Hound will follow the carbon tracking.
There are better tracers out there now, but Cable Hound is the only one I have used.
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08-09-2010, 04:26 PM #3
I would think with an ohmmeter you may be able to check between a neutral or a bare ground and the remaining power wires. No continuity would identify the broken wire.
I'm not sure what good this will do you though as pulling only ONE of a group in a conduit may be a bear...especially when they are aluminum. If it were me, which it isn't, I would be inclined to pull them all and replace them with copper.
Be sure to pull a 'pig' using the existing wires if you are going to replace them.
08-09-2010, 04:28 PM #4
Aluminum is known for connection issues, either due to mechanical or corrosion problems. (Still used a lot, though...) Check the path before you grab the shovel.
With both ends disconnected, it might be possible to find the break with a utility locating device. For plastic gas lines, they run a chaser wire that is connected to a transmitter when locating the wire. You would run it from each end, and where 'trails off' is about where the break is.
Fixing it could be false economy, though. Conduit is your friend.
08-09-2010, 04:28 PM #5
There is a device called a "Wire Break Locator" although it is mostly used for the pet invisible fences. It may do the trick.
Could you not call your local utility? or is this feed something they shouldn't know about?
See if you can find an private electrical contractor and maybe for the price of a six-pack he'll give you a hand.
When I was a slum-lord, my tenant called to say that they had lost power to half the house - same thing had happened to them. The cause was the Mexican family next door. The Mexicans had decided to do some digging in the yard and nicked the underground entrance cable. Fortunately no one was hurt.
08-09-2010, 04:34 PM #6
I suppose you have already thought of peeing on the ground.
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08-09-2010, 04:34 PM #7
I'm with Stuart on this, if you know there's power at the pole and none at your meter.
Unless it's an incredibly long run and you plan to place (and code will allow?) both an electrical and Christy box at the point of the break, you're probably committed to pulling everything. If it's UF (direct burial cable), you'll still have to open the whole trench.
08-09-2010, 05:31 PM #8
A device called a time domain reflectometer is used by companies with a lot of money. It sends an electrical pulse down the wire which is reflected back by the break. The time between the initial pulse and reflected one gives you the distance to the break. It amounts to a wire radar. Since it doesn't require detection external to the wire or conduit, it works on buried cables as well as open ones. If you can find a friendly telephone or electric company man, you might get him (or her, to be politically correct) to check your wire, you would know the distance away to dig.
08-09-2010, 06:01 PM #9
I second 9100. I had this trouble a couple of years after building my workshop, I noticed one leg of the 220 volt outlet to my saw was out. I called a local company which advertised in the yellow pages as being able to find breaks. They actually fed a signal into the breaker box in the shop, then located the fault with a detector folowing the route of the cable. The insulation had been nicked on one wire, and the cable had corroded to aluminum oxide. In the process, the aluminium oxide expanded to the point the insulation split. In short, try the yellow pages.
08-09-2010, 06:04 PM #10
Locally the power company is responsible for the wire to the meter, the owner from the meter to everything else.
Unless there is physical damage to one leg it is not likely that it burned through under ground.
Aluminum wire is more likely to expand and contract than copper and work loose the pressure connections. It may be in the meter box or any connection between the pole and where you don't have juice.
Here the meter box is sealed.
I would call the power company first. If it is the connection in the meter box they will fix it. If it is not, they will tell you it is your problem.
If you have a disconnect just past the meter, start there with a voltmeter and test both hot legs to ground.
If you are not comfortable poking around in 240 volts with almost unlimited amps, get some help.
Look at the connections. The bare wire should have some anti corrosion goop on it and the connection should be tight.
If you can't turn off the power without pulling the meter, you need an electrician. If you can turn off the power, do so, and test from each hot leg to ground.
If no voltage, tighten each connection, looking for indications of melted insulation or heat. A burned off stub of wire is a giveaway.
If you are not experienced with messing with house electricity get help, you can get very dead, very quickly.
08-09-2010, 06:04 PM #11
Years ago we had an underground line short out, not a complete break. Talked to the power company & they sent a man out who IIRC put some kind of high voltage source on the line (which had to be disconnected on both ends (I think). Then he went over the approximate location of the line with a device something like a metal detector & located the short within a couple of feet on a line about 200 feet long. Unfortunately, it was in the middle of winter & we had to use a jackhammer to dig it up. I do not know what the device was called. Good luck, Earl
08-09-2010, 06:13 PM #12
I thought Bob had noted that the break appeared to be between the meter (on garage) and the house. This would be HIS domain! If he hired someone to find the break..........then what?? A 3M underground splice kit costs about $300...If one leg is dead and it's single conductors in a conduit, it will have to be pulled and replaced, end of story!
If one leg is dead, who cares where it is! it has to be replaced. Maybe I don't understand the big picture here.
08-09-2010, 06:41 PM #13
I had no idea a splice kit is that kind of money, thats more than the 100' of wire cost! Guess its digging time. BTW its not in conduit.
08-09-2010, 08:16 PM #14
12-10-2012, 12:52 AM #15
$300? I pay $9-25 for a typical direct burial splice depending on size. If you do splice AL, use anti-oxident paste and a torque wrench/screwdriver. I would definitely be checking the connections at the meter before digging.
JoeE. liked this post
12-10-2012, 03:10 AM #16
Well for first one is easy to detect but second one need some technique.
I gone through an article and want to share with you all
How to Find a Break in Underground Wiring | eHow.com
read it and let me know if it is helpful.
12-10-2012, 07:56 AM #17
This kind of issue is why I don't like installing direct burial cables, especially with Al conductors. All it takes is a tiny nick in the insulation to let moisture in, and the conductors literally fall apart from corrosion in a very short time. Sure, you'll save money up front, but once something like this happens, you'll really wish that you spent the extra money to run conduit so new conductors can be pulled in without digging up the whole run.
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12-10-2012, 08:04 AM #18
12-10-2012, 08:08 AM #19
12-10-2012, 08:27 AM #20
Maybe a filter that if the last post is over a year ago and the poster has less than 10 posts, it's probably a spammer and not to allow it?