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Thread: Ground Rod Demonstration

  1. #1
    Join Date
    Aug 2018
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    Binghamton NY
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    Ground Rod Demonstration

    Hello,

    I would like to preform a demonstration for my class for our grounding and bonding section. I am curious if anyone has taken a ground rod , separate from the buildings grounding system, and hooked it to 120V(off a breaker). This was mentioned in Mike Holts grounding and bonding myths lesson. I am using this is illustrate the concept of current using the ground to complete a circuit . I want to know if anyone has done this and what safety protocols you put in place to ensure the experiment was conducted safely .

    Thanks.

  2. #2
    Join Date
    Dec 2010
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    Tennessee NEC:2008
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    Here is a video that Mike Holt made on ground rods.

    If you aim at nothing, you will hit it every time!

  3. #3
    Join Date
    Jul 2003
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    New Jersey
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    Quote Originally Posted by Weaton325 View Post
    Hello,

    I would like to preform a demonstration for my class for our grounding and bonding section. I am curious if anyone has taken a ground rod , separate from the buildings grounding system, and hooked it to 120V(off a breaker). This was mentioned in Mike Holts grounding and bonding myths lesson. I am using this is illustrate the concept of current using the ground to complete a circuit . I want to know if anyone has done this and what safety protocols you put in place to ensure the experiment was conducted safely .

    Thanks.
    Do not do this (OK I did try it in my own house). Hooked the GEC from the rod directly to a 20 amp breaker and turned it in. If I remember correctly when I measured current with an Amprobe it read 4 amps.
    Rob

    Moderator

    All responses based on the 2014 NEC unless otherwise noted

  4. #4
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    May 2018
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    Hmm... have me wondering if I run three ground rods..l hook live to one, ground pin to two, neutral to three, and they are four feet apart... then run this to an RCD... how long before the circuit tripped, or even would it? Hmmm... maybe one day...

  5. #5
    Join Date
    Oct 2007
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    New Jersey
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    Quote Originally Posted by Adamjamma View Post
    Hmm... have me wondering if I run three ground rods..l hook live to one, ground pin to two, neutral to three, and they are four feet apart... then run this to an RCD... how long before the circuit tripped, or even would it? Hmmm... maybe one day...
    Pretty close to "never", or thereabouts. See the video that Little Bill linked to. Eventually they drive the ground rod down to about 50 feet IIRC and the resistance was still about 13 ohms or some such, not low enough to clear a fault at the panel.

  6. #6
    Join Date
    Oct 2013
    Location
    newburgh,ny
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    450

    use a fence charger

    A controlled way to do it is with a electric fence charger, current is limited. They make small ones for dogs cheaper and less distance.

    Hook up the charger as shown in manual.
    Using insulated gate handle and insulated wire made for chargers, hold handle 1" give or take from rod. Nice white/blue arc and snap.
    Now repeat at 1 foot intervals useing the dirt or grass. Arc will get smaller and less pop.

    Cowboy
    A cowboy may get thrown , but they always get up and walk forward.

  7. #7
    Join Date
    Dec 2004
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    North Carolina
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    Use Ohm’s law to demonstrate, E=IxR
    120 volts divided by 25 ohms equals 4.8 amps
    Mike Whitt
    God answers Knee-Mail.

  8. #8
    Join Date
    Jul 2013
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    Resting under the Major Oak UK
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    Quote Originally Posted by infinity View Post
    Do not do this (OK I did try it in my own house). Hooked the GEC from the rod directly to a 20 amp breaker and turned it in. If I remember correctly when I measured current with an Amprobe it read 4 amps.
    Similar to the method I used on my own house except I put an old 2kW 250V heater element in line. I got the full 8A flowing in to the earth electrode.

    OK I cheated a bit with the earth electrode. I had to dig out all of the drains to replace the piping and so ran a copper tape alongside the new pipe. Digging out a new drain chamber I found a redundant gas main, so I brazed a stud to it.

    Deep driven rods in North Derbyshire UK you haven’t a chance without drilling. I’d got a 600 Ft shallow earth electrode for more or less for nothing.
    The reports of my death are greatly exaggerated.

  9. #9
    Join Date
    Oct 2007
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    New Jersey
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    Quote Originally Posted by Tony S View Post
    Similar to the method I used on my own house except I put an old 2kW 250V heater element in line. I got the full 8A flowing in to the earth electrode.

    OK I cheated a bit with the earth electrode. I had to dig out all of the drains to replace the piping and so ran a copper tape alongside the new pipe. Digging out a new drain chamber I found a redundant gas main, so I brazed a stud to it.

    Deep driven rods in North Derbyshire UK you haven’t a chance without drilling. I’d got a 600 Ft shallow earth electrode for more or less for nothing.
    How did you know it was redundant? Finding out otherwise could have been an...uplifting experience.

  10. #10
    Join Date
    Feb 2005
    Location
    Charlotte, NC
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    6,779
    This is an oldie but a goodie, go to about 5 minute mark for some ground rod tests

    https://www.youtube.com/watch?v=hG2p9N1MHlk

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