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Underground fault

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  • Underground fault

    I attempted to locate a bad wire today with no luck.
    Its a 400' run 240v with neutral and no egc. The wire is direct burry USE. Half the run is burried in sand and the other half thru a flower bed till it gets to the house panel. Alum wire. Only one conductor meggers bad. The voltage is at 60v when it reaches the sub panel at the pier.

    I am using an Amprobe AT-2005 and a Ridgid Seektech SR-20 locator.
    I got different results with the amprobe when I tried different methods.
    Does anyone have experience in this situation that may be able to tell me how to use my locators better to find this.

    All of my traces were using only the bad wire. I get a good trace the full length of the bad wire so its not an open which would be easier to find.

    I looked for loss of signal and led me to different spots. I spent 2.5 hrs on it today and plan to go back tomorrow.

  • #2
    Re: Underground fault

    you could possibly use an ohm meter or megger and a probe and an additional piece of wire and probe a long the wire line until you find the least resistance,

    or try from both ends to earth and see if there is a difference of resistance,
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    • #3
      Re: Underground fault

      For electrical wires, get a Fluke/Harris TS90 or TS100 time domain reflectometer. It's accuracy is 1% of the range with max range being 2500 feet. So if you have a 400 ft run, you will be within 4 FT of fault (it's actually a lot more accurate than manufacturer spec, you will be within 1 ft). It shows the distance in feet to open or short. Use your seektech to map out your distances if it's not a straight run.
      Last edited by DRC-Wartex; 10-16-2008, 08:48 PM.