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  1. #1

    Default Electric Ground Hot to the Touch

    This afternoon during a home inspection I was clearing weeds away from the ground rod and noticed the ground rod was "hot" to the touch. Temperature measured 195 Degrees F when checked with thermo image camera.
    Checked the ground rod and wire with a volt sniffer - no indication of voltage noted.
    Ground clamp was cracked. Stranded wiring at ground rod - a few of the wire strands were loose / not clamped.
    All electric outlets inside the house show grounded with a 3 prong electric outlet tester.
    1977 built house with a "quality" Zinsco panel and all copper wiring. Surprised that only one circuit breaker inside the main panel appears to be loose.
    As always I will recommend replacement of Zinsco panel and checking ground system by a licensed electrician.

    My question for my own piece of mind is what could be causing the high temperature at the ground rod? Insufficient ground cable? Loose ground cable? Zinsco panel? Improper ground rod (too short)? All of the above? None of the above?

    Thanks, Larry

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  2. #2
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    Default Re: Electric Ground Hot to the Touch

    Quote Originally Posted by Larry Heitzenrater View Post
    My question for my own piece of mind is what could be causing the high temperature at the ground rod? Insufficient ground cable? Loose ground cable? Zinsco panel? Improper ground rod (too short)? All of the above? None of the above?
    F. None of the above.

    Do you carry a clamp-on ammeter? If you don't have one, you need to get one.

    If you had placed a clamp-on ammeter around that ground rod ... I am guessing that you would have been reading A LOT of amperage.

    Overhead service or underground?

    If overhead, what did it look like at the weather head? What was the neutral conductor like? Corrosion to the phase 'hot' conductor?

    I am guessing that the neutral was bad 'someplace' - could be at that panel, but more likely deteriorated and 'bad' someplace along the neutral conductor.

    Think of it this way - the neutral conductor is a resistor (it is) and it is normally a very very low ohm resistor, but if the neutral goes 'bad' then it becomes a very high ohm resistor, and, if 'bad enough' it becomes a switch which 'opened' and shut the current flow off.

    The neutral is how the unbalanced current gets back to the transformer (with a very little bit going down through the ground rod, through earth ground, and back to the transformer that way) ... usually anyway. When the neutral goes 'bad', everything that is not going back through the neutral to the transformer now has to find another way back, and that will quite possibly be the ground rod and earth to the transformer.

    Being as the ground rod, clamp, etc, is NOT INTENDED to carry any current ... and the neutral current is now trying to use that as its path back to the transformer ... it will get warm anyway, now factor in a cracked clamp and poor condition conductor and the resistance at the clamp/ground rod will go up, which means the heat goes up as the resistance goes up.

    Just a possibility - the only way to know for sure would be to use a clamp-on ammeter and check it.

    I remember that a few of the inspectors here have measured over 10-15 amps at times - not good, should be -0- amps or close to -0- amps.

    BUT ... HERE IS ANOTHER possibility - a LARGE GROUND-FAULT somewhere which was putting a lot of current on the equipment ground wire someplace and taking that back to the panel - was anything hot (temperature-wise) in the panel? If so, that might well be the cause of the current down the ground rod.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

  3. #3

    Default Re: Electric Ground Hot to the Touch

    Thanks Jerry.

    Yes I carry a clamp-on ammeter. I didn't think to check current at the ground rod. The house is vacant so I will be able to stop be tomorrow to check that.
    The service is overhead - the weather head looked good. Not one of the ones with a sheet metal cover that rusts through.
    No corrosion inside the panel, but I will look at the conductors at the weather head tomorrow.
    None of the circuits inside the panel were hot - I checked with thermo camera.

    Thanks again - I will let you know what I find tomorrow.

    Larry


  4. #4
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    Default Re: Electric Ground Hot to the Touch

    Just to add the Jerry's comments, the ground rod has nothing to do with the normal operation of the service. Also the ground rod has nothing to do with grounding a receptacle.

    All answers based on unamended National Electrical codes.

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    Default Re: Electric Ground Hot to the Touch

    Be careful not to "tug" on the ground wire, rod, etc. as I have heard some do. Remember this IS a LIVE Circuit and can become a deadly one if you mess with it.
    If the ground wire, clamp, or electrode does not have a good connection to earth then YOU can easily become a ground path when you touch it!
    Without knowledge and care, don't make the mistake of thinking there is no current/voltage on the ground wire. You never know when there is a bad connection that you might accidentally find.

    Jim Luttrall
    www.MrInspector.net
    Plano, Texas

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    Default Re: Electric Ground Hot to the Touch

    Quote Originally Posted by Jim Port View Post
    the ground rod has nothing to do with grounding a receptacle.
    Why doesn't it?


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    Default Re: Electric Ground Hot to the Touch

    Quote Originally Posted by Jim Port View Post
    Also the ground rod has nothing to do with grounding a receptacle.
    Quote Originally Posted by Roy Lewis View Post
    Why doesn't it?
    The ground for a receptacle is the equipment ground wire which goes back to the service equipment where it is connected to earth ground .. but ... the neutral is also connected to earth ground - both at the service and at the transformer ... the receptacle ground will check as being grounded even if the grounding electrode system was not installed or was disconnected.

    This is because the neutral is bonded to the equipment ground at the service equipment.

    The hot - ground and neutral - ground relationship at the receptacle is related to the neutral - ground bond at the service equipment. Reverse polarity indicates that the polarity between the service equipment and the receptacle has been altered/miswired.

    Jerry Peck, Construction / Litigation Consultant
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    Default Re: Electric Ground Hot to the Touch

    Quote Originally Posted by Jim Luttrall View Post
    Be careful not to "tug" on the ground wire, rod, etc. as I have heard some do. Remember this IS a LIVE Circuit and can become a deadly one if you mess with it.
    If the ground wire, clamp, or electrode does not have a good connection to earth then YOU can easily become a ground path when you touch it!
    Without knowledge and care, don't make the mistake of thinking there is no current/voltage on the ground wire. You never know when there is a bad connection that you might accidentally find.
    Theoretically ... removing the ground clamp from the ground rod does not matter or affect anything ... theoretically ... then real life happens and something goes wrong ... at which time Jim's advice could be a life saver or at least an electrical shock saver ... especially if the ground rod is warm or hot temperature - wise.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
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    Default Re: Electric Ground Hot to the Touch

    What about lightning protection with an improperly earth grounded system?


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    Default Re: Electric Ground Hot to the Touch

    Quote Originally Posted by Roy Lewis View Post
    Why doesn't it?
    Again piggybackingon Jerry's comments, you can short a hot to a ground rod and the breaker will not trip. The resistance of earth is too high. To trip a breaker relies on the neutral to ground bond in the service panel.

    All answers based on unamended National Electrical codes.

  11. #11
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    Default Re: Electric Ground Hot to the Touch

    Quote Originally Posted by Roy Lewis View Post
    What about lightning protection with an improperly earth grounded system?
    That is what the ground rod is for - but the question asked about receptacles, so I didn't mention a lightning strike.

    If one is out there in a lightning storm and intentionally grab the ground rod ... they are not the brightest bulb in the box ... at least not the brightest until they light up from the strike ...

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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