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Thread: Voltage drop in underground cable

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  1. #1
    DIY Junior Member silverfox52009's Avatar
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    Default Voltage drop in underground cable

    I have a problem with the underground wire feeding my cabana I run a 110 volt pump to water my lawn as I am on a river ,I have done this for the past twenty years . This year I plugged in the pump and nothing so I removed the gfi receptical and put my tester on the wires comming out of the ground and got a reading of 62 volts. I then went to the panel and tested from the breker to neutral and got 120 volts.I am wondering if maybe something has bitten through the neutral wire ? Is this possible I would appreciate any advice you can give thanx in advance Fred

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    Retired Defense Industry Engineer jadnashua's Avatar
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    A loose or corroded connection anywhere on the run might show up as a low voltage at the end. Does the cable have a ground wire? What's the voltage between hot and ground?
    Jim DeBruycker
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    Electrician ActionDave's Avatar
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    My bet would be a break in the wire underground somewhere.

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    DIY Junior Member silverfox52009's Avatar
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    Quote Originally Posted by jadnashua View Post
    A loose or corroded connection anywhere on the run might show up as a low voltage at the end. Does the cable have a ground wire? What's the voltage between hot and ground?
    yes it does have a ground wire and the voltage between hot and ground is the same 62 volts

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    DIYer, not in the trades LLigetfa's Avatar
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    A high resistance on the feed would result in a voltage drop that is commensurate with the current draw. A high impedance voltmeter testing a circuit that is not under load usually does not give a true picture since it in and of itself, provides no current draw.

    My guess is that along with the high resistance, there is also a short to ground.

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    Moderator & Master Plumber hj's Avatar
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    quote; yes it does have a ground wire and the voltage between hot and ground is the same 62 volts

    That would imply a problem with the "hot' wire, not the neutral.
    Licensed residential and commercial plumber

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    Jack of all trades DonL's Avatar
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    Quote Originally Posted by LLigetfa View Post
    My guess is that along with the high resistance, there is also a short to ground.
    I don't think that is correct.

    hj is correct.

    A short reading from Ground to Neutral is normal, at the source.

    The open is on the Hot leg, if there is a open.

    Or if the pump is trying to run, it may be locked up and not running. that could explain the voltage drop.

    You can use a light bulb for better testing under a small load.
    Theory only works perfect in a vacuum.

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