Outdoor wiring short

DBVogtOctober 11, 2011

Is there a way to locate a short in a wire? My lamppost light is connected to an outdoor GFCI outlet. Recently the outlet tripped and will not stay on. I disconnected everything at the outlet and the light and tested with an ohmmeter. There is a partial short between the black wire and ground. The wire looks in pretty good condition. I've done wiring for many years and have never found a short in the actual cable - always at a connection. No one was digging in the vicinity of the cable. It's possible that someone years ago cut the cable to install flower bed lights but I haven't seen any. Are there devices to detect electrical leakages? I really hate to have to dig up the lawn and go under sidewalks to replace the cable. Any suggestions?

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randy427

I haven't found any test equipment that would be practical for this.
I'd dig at the base of the light to see if the cable is nicked close to where it goes into the post. If that isn't it, I'd examine where it leaves the GFCI and goes underground.

    Bookmark   October 11, 2011 at 10:54PM
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hendricus

Have you tried just putting a new GFCI in? I had one trip and wouldn't reset in the middle of the yard. Put a new one in and it's been fine for over a year now.

    Bookmark   October 12, 2011 at 5:47PM
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DBVogt

Thanks for the replies. Haven't tried a new GFCI as I disconnected everything from the cable and still found a short. A new GFCI would still trip. I did dig up a couple of feet of cable near the GFCI and found no problems. After the GFCI, the cable goes under bushes, a fence, sidewalk, lots of shrubbery and finally the lawn to the lamppost. It's beginning to look like the base of the lamppost is the next step to look. The wire at the top looked fine.

    Bookmark   October 12, 2011 at 8:02PM
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brickeyee

Divide and conquer.

Try completely disconnecting the light completely from the cable and heck each separately.

If the cable still reads bad it need to be repaired or replaced.

Their are kits available for a repair on buried cables, but finding the damaged spot is often just as much trouble as running a new cable (lots of very careful hand digging with the possibility of further cable damage).

Now you understand why conduit is preferred.
You can always pull new wires into a conduit, and even non-metallic condition provides more protection than UF cable.

If you use rigid metal or intermediate conduit the fill depth can be as low as 6 inches, greatly decreasing the installation work over the 12-18 inches for non-metallic conduits.

    Bookmark   October 14, 2011 at 10:06AM
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jmorrow

we have a unit for this, its made by Greenlee. not sure of model #, but buying the unit would be ridiculously more money than replacing the cable. I want to say it cost 3k. it pulses a very high voltage DC current through one end of the wire from the main unit. then, it has a remote unit that you use to find the fault. it has 2 probes on it with an analog display. it picks up the pulsed current from the Nick in the wire through the probes, and the needle will point towards the probe that is closest to the fault. so you just keep moving the remote unit whichever way the needle points until you have it centered from every direction, then you dig in that spot. works like a champ, and if it doesn't find anything the the problem is in the above ground portion of the wiring. maybe you can find someone willing to rent you one, but I doubt it. so unless not digging up your yard is worth three grand, hope you're good with a shovel.

    Bookmark   October 16, 2011 at 4:14AM
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jmorrow

found it greenlee pe2003.

www.discount-low-voltage.com/Tools-Testers/Buried-Facility-Locating/GR-PE2003

looks like they've dropped the price only cost a grand now. we bought ours a long time ago. still works great though, and more than pays for itself if you're an ec. we've gotten countless wom jobs just because of this baby.

    Bookmark   October 16, 2011 at 4:22AM
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