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Thread: Ground Potential Rise

  1. #1
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    Ground Potential Rise

    I came across this article which talks about ground potential rise from having unbonded grounding electrodes. Its very eye opening and I wish Mike Holt would do a new letter or a you Tube video on CATV bonding. I know there are many misconceptions about this. At my own home for example the CATV has its own ground rod...


    http://electrical-engineering-portal...e-in-your-home


    what do others think about this article? Right from an electrical theory standpoint?
    I'm in over my head...

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    I have the attention span of a gnat so wading through all that text for about three minutes was about all I could stand.

    If I understood correctly the point of the article is that driving extra ground rods is a bad idea, and you are making things worse if you add extra ground rods that don't tie back to the main service. If that is correct then I agree.
    If you go and decide to dance with a gorilla the dance ain't over till the gorilla decides it's over.

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    Quote Originally Posted by ActionDave View Post
    I have the attention span of a gnat so wading through all that text for about three minutes was about all I could stand.

    If I understood correctly the point of the article is that driving extra ground rods is a bad idea, and you are making things worse if you add extra ground rods that don't tie back to the main service. If that is correct then I agree.
    Yes- nice synopsis
    I'm in over my head...

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    Quote Originally Posted by mbrooke View Post
    Yes- nice synopsis
    Isn’t this the reason for an Inter Systems Bonding Terminal? The one we are required to put in, but no one uses.
    Tom
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    Quote Originally Posted by ptonsparky View Post
    Isn’t this the reason for an Inter Systems Bonding Terminal? The one we are required to put in, but no one uses.
    Yes- but you have seen the reality.
    I'm in over my head...

  6. #6
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    Quote Originally Posted by mbrooke View Post
    I came across this article which talks about ground potential rise from having unbonded grounding electrodes. Its very eye opening and I wish Mike Holt would do a new letter or a you Tube video on CATV bonding. I know there are many misconceptions about this. At my own home for example the CATV has its own ground rod...


    http://electrical-engineering-portal...e-in-your-home


    what do others think about this article? Right from an electrical theory standpoint?
    Theory is mostly accurate.

    NEC does require bonding CATV to electrical system, as well as other systems. Had this requirement even before the intersystem bonding terminal was added.

    You can drive all the rods you want for other systems if that makes you feel good - but they also all need to be bonded together.

    Even when all such systems are bonded, the more direct the lightning strike is the more likely you have temporary rise in voltage in some instances or even certain portions of a premises.
    I live for today, I'm just a day behind.

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    Quote Originally Posted by kwired View Post
    Theory is mostly accurate.

    NEC does require bonding CATV to electrical system, as well as other systems. Had this requirement even before the intersystem bonding terminal was added.

    You can drive all the rods you want for other systems if that makes you feel good - but they also all need to be bonded together.

    Even when all such systems are bonded, the more direct the lightning strike is the more likely you have temporary rise in voltage in some instances or even certain portions of a premises.
    I'd imagine- I remember mike saying that the frequency pulse of lightning is so high that even a few feet of #6 will exhibit significant impedance.

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    Quote Originally Posted by mbrooke View Post
    ...At my own home for example the CATV has its own ground rod...
    Around here, they don't even bother with that, let alone connect to the ISBT.

    One of my radio station clients added cable internet in between my usual visits. The CATV tech mounted his first splitter 3 feet from the main ground bar. He left it float, and by the time I discovered it, a surge roared in and took out the cable modem, router and one of the ethernet switches. What a mess.
    Gregg

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    Quote Originally Posted by grich View Post
    Around here, they don't even bother with that, let alone connect to the ISBT.

    One of my radio station clients added cable internet in between my usual visits. The CATV tech mounted his first splitter 3 feet from the main ground bar. He left it float, and by the time I discovered it, a surge roared in and took out the cable modem, router and one of the ethernet switches. What a mess.
    Bonding is more important than grounding. In fact article 250 is mostly around bonding, not grounding. Grounding has little if anything to do with people and property protection at 600 volts and under.
    I'm in over my head...

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    Quote Originally Posted by mbrooke View Post
    Grounding has little if anything to do with people and property protection at 600 volts and under.
    1)Grounding dissipates surge energy lest it should do harm.
    2)In case of Mv to LV accidental contact, grounding on LV side limits ground potential rise.

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