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Thread: ground rod, will not open breaker.

  1. #11
    Join Date
    Dec 2012
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    Placerville, CA, USA
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    Quote Originally Posted by mbrooke View Post
    And thats why we bond the water pipes. The NEC is not stupid, thats for sure.


    Yes- a ground rod will not trip a standard breaker at 120 volts. And even if it did or does, the NEC does not allow a ground rod to act as a fault current path.
    More accurately the NEC requires a *fault-clearing* path.
    You can't prevent a rod from being a fault current path, current division by conductance being what it is. But you cannot let the rod be the only fault current path, nor even a parallel path which is necessary for fault clearing through the OCPD.

    Sent from my XT1585 using Tapatalk

  2. #12
    Join Date
    Jan 2011
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    United States
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    Quote Originally Posted by GoldDigger View Post
    More accurately the NEC requires a *fault-clearing* path.
    You can't prevent a rod from being a fault current path, current division by conductance being what it is. But you cannot let the rod be the only fault current path, nor even a parallel path which is necessary for fault clearing through the OCPD.

    Sent from my XT1585 using Tapatalk
    Good point- wrong choice of words on my part.
    What is esoteric knowledge today will be common knowledge tomorrow.

  3. #13
    Join Date
    Jan 2018
    Location
    SE Michigan
    Posts
    23
    Quote Originally Posted by reyamkram View Post
    is it true that a ground rod is only used for lighting, and will not open a breaker, when there is a ground fault, and I was told that is no purpose, putting ground rods on industrial machinery, and the ground rod can do more harm then good, if lighting hit close to the building, it can go up to the ground rod and fry the machine

    Thank you, for all and any information, on this subject.
    For an explanation see this video starting at the 45 minute mark for this specific case example about adding a supplemental earth electrode at a machine location.

    https://www.youtube.com/watch?v=mpgA...ature=youtu.be

    It's well worth your time to study the entire thing, but the 45 minute mark addresses the bolded part specifically. It's not against code to add a supplemental earth electrode, but is not best practice in most cases. Best practice is to pull a dedicated isolated equipment grounding conductor with the supply conductors, and connect to the main service electrode bonding point.

    The idea is that when a surge pulse comes along and enters the system somewhere, be it from the utility, the sky or the earth, you want everything bonded together at the same exact potential reference. So that EVERYTHING rises and falls in unison, with the disturbance pulse.

    It is when you have differing connection points that gives you, differences of potential between those different connection points, that can cause damage, when current flows to dissipate the surge. Small differences in impedance and resistance in the earthing system, can result in large current flows, while the disturbance pulse is dissipating.

    MTW

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