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Thread: Odd intriguing and perhaps dangerous multi unit grounding question/problem: JUMPER??

  1. #11
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    Thx Jumper, your reply confirms my basic thinking:) My theory is

    that 2 of the 4 go to secondary GES and other two are on sub panel


    WEIRD!!

  2. #12
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    Quote Originally Posted by docj67 View Post
    If they do land on other subpanel bar in fact and i ve yet to prove that conclusively, that would be violating as you say

    250.24(A)(1).

    If that is the case is there a risk for unpredictable behavior in subpanel if say there's a ground fault incoming to the subpanel?

    Also this scenario if true has a ground loop between customer service and subpanel.....

    going to recon
    250.24(A)(1).

    THX !!
    A GES has nothing to do with clearing ground faults. If the EGC system is correct, then whatever’s happening with these GECs/ wires will not effect operation of the OCPDs.

    Might be some unwanted/illegal parallel paths for neutral current though.

    Quote Originally Posted by docj67 View Post
    My interpretation is that it would be a violation BC it does not bond directly to building electrode.

    Care to shed some wisdom from this scenario if true relative to 250.24(A)(1).?

    thx!
    Does the main distribution panel have a correct connection to a proper GES?

    Quote Originally Posted by docj67 View Post
    that 2 of the 4 go to secondary GES and other two are on sub panel


    WEIRD!!
    I have no clue what you mean here, other than it seems that some wires are crossed up or landed incorrectly. Secondary GES???
    "Electricity is really just organized lightning." George Carlin


    Derek

  3. #13
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    Quote Originally Posted by jumper View Post
    A GES has nothing to do with clearing ground faults. If the EGC system is correct, then whatever’s happening with these GECs/ wires will not effect operation of the OCPDs.

    Might be some unwanted/illegal parallel paths for neutral current though.



    Does the main distribution panel have a correct connection to a proper GES?


    --there's no main, there are 4 mains, one for each unit as per picture. I have yet to open gutter or other customers' service can.


    I have no clue what you mean here, other than it seems that some wires are crossed up or landed incorrectly. Secondary GES???

    That is the $64,000,000 question. We dont know. What we do know is that building GES likely is not to code, and it appears my customer's subpanel has 1-2 GEC's attched to it from other unit's services. I assume GES= Grounding Electrode System. My understanding regarding groundfaults is that a EGCis needed to bond to system GES vai GEC to clear them and if there's no GEC to GES they remain active until removed.

    In anycase, it appears impossible for any of us to get clearer via this means of communication....... If you might please define OCPD and how whatever it is that does make sense to you here violates 250.24(A)(1).

    Thanks so much for all efforts!!

  4. #14
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    GEC versus EGC versus GES defined

    Grounding Electrode conductor- runs from service to GES
    Grounding Electrode system- 1 or more electrodes as defined by 250.52A
    EGC-Equipment grounding conductor--per branch circuit bonded to all metal cans / devices on a given branch circuit

    Sorry if my use of terms other than these is confusing.

    Do these definitions match your usage/understanding?

    Thx so much!

  5. #15
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    Quote Originally Posted by docj67 View Post
    Grounding Electrode conductor- runs from service to GES
    Grounding Electrode system- 1 or more electrodes as defined by 250.52A
    EGC-Equipment grounding conductor--per branch circuit bonded to all metal cans / devices on a given branch circuit

    Sorry if my use of terms other than these is confusing.

    Do these definitions match your usage/understanding?

    Thx so much!
    Yes. Note that EGCs are not limited to branch circuits, feeders have one also. A feeder EGC would bond a sub panel, fused disco or such.
    "Electricity is really just organized lightning." George Carlin


    Derek

  6. #16
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    Quote Originally Posted by docj67 View Post
    That is the $64,000,000 question. We dont know. What we do know is that building GES likely is not to code, and it appears my customer's subpanel has 1-2 GEC's attched to it from other unit's services. I assume GES= Grounding Electrode System. My understanding regarding groundfaults is that a EGCis needed to bond to system GES vai GEC to clear them and if there's no GEC to GES they remain active until removed.

    In anycase, it appears impossible for any of us to get clearer via this means of communication....... If you might please define OCPD and how whatever it is that does make sense to you here violates 250.24(A)(1).

    Thanks so much for all efforts!!
    Your understanding of the GES is incorrect. Read below, nothing about clearing faults.

    250.4
    (A) Grounded Systems.
    (1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.

    Informational Note: An important consideration for limit- ing the imposed voltage is the routing of bonding and grounding electrode conductors so that they are not any longer than necessary to complete the connection without disturbing the permanent parts of the installation and so that unnecessary bends and loops are avoided.

    (2) Grounding of Electrical Equipment. Normally non– current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equip- ment, shall be connected to earth so as to limit the voltage to ground on these materials.
    "Electricity is really just organized lightning." George Carlin


    Derek

  7. #17
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    Thank you...

    Perhaps as I am still getting used to matching NEC veribiage to field experience, I misspoke.
    I'm afraid to comment further less more confusion results.

    I did not mean imply whatever I did to suggest that 250.4 referenced clearing ground faults.

    Thx again for all the feedback.


    Quote Originally Posted by jumper View Post
    Your understanding of the GES is incorrect. Read below, nothing about clearing faults.

    250.4
    (A) Grounded Systems.
    (1) Electrical System Grounding. Electrical systems that are grounded shall be connected to earth in a manner that will limit the voltage imposed by lightning, line surges, or unintentional contact with higher-voltage lines and that will stabilize the voltage to earth during normal operation.

    Informational Note: An important consideration for limit- ing the imposed voltage is the routing of bonding and grounding electrode conductors so that they are not any longer than necessary to complete the connection without disturbing the permanent parts of the installation and so that unnecessary bends and loops are avoided.

    (2) Grounding of Electrical Equipment. Normally non– current-carrying conductive materials enclosing electrical conductors or equipment, or forming part of such equip- ment, shall be connected to earth so as to limit the voltage to ground on these materials.

  8. #18
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    Quote Originally Posted by docj67 View Post
    Perhaps as I am still getting used to matching NEC veribiage to field experience, I misspoke.
    I'm afraid to comment further less more confusion results.

    I did not mean imply whatever I did to suggest that 250.4 referenced clearing ground faults.

    Thx again for all the feedback.
    Okay maybe I was wrong and you understand the difference between grounding and bonding, but your following statement implies to me there was a bit of confusion:

    Quote Originally Posted by docj67 View Post
    I assume GES= Grounding Electrode System. My understanding regarding groundfaults is that a EGCis needed to bond to system GES vai GEC to clear them and if there's no GEC to GES they remain active until removed.
    From that wording I had inferred that a little theory on the subject would be useful to you.

    If I/we seem to be a bit hardcore about correct terminology, it is because if we all do not use the same terms and definitions then confusion results.

    Remember, we are spread out in all the states and also a few countries, so keeping an established common language of terms, definitions, and such is essential for effective communication.

    Also writing out what you actually mean is quite difficult for most of us. What we write is not always what we mean or it is written in a way that can interpreted more than one way.

    And some times one’s brain just goes haywire and the resulting post is a bit whacked. Trust me I know, posted more than one doozy myself. It happens. Most members here are a forgiving lot if one just says “Oops” or “ My bad”.

    Now, as far as your installation is concerned - at this point I think I now have a pretty good idea what you are facing. Later I will post what I percieve and you can correct me as needed.
    "Electricity is really just organized lightning." George Carlin


    Derek

  9. #19
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    excellent

    I reread some of my postings and I see how they could have been misinterpreted!- thx

    I like that this forum IS hardcore about terminology--I will be more precise going forward.

    In the meantime, I'm mostly curious about :

    1) what is an OCPD?

    2) How specifically does running an EGC to a subpanel ground bar violate 250.24(A)(1). I read 250.24(A)(1 several times. My training and experience ( lol ) tells me its wrong irregardless of
    250.24(A)(1) but the verbiage is so damn dense I was unable to make the intellectual link.

    I'm not too concerned about solving the issue but I would like to better understand from an practical POV what the possible issues are from such a whacked build out. If those 4 GEC's aren't bonded to metal framing that is hidden then the whole issue is sorta moot and only worthwhile as intellectual fodder The solution is to snip those 4 GEC's and drop in two new ground rods according to NEC rules.

    I began this dialogue in an attempt to learn what sort of problems could be created by landing service GEC's on a subpanel not part of the services per se. The fix is straightforward: Correct buidling GES and unit GEC's to code. Boom!

    I hope this is clear sir My tele can be given by PM if u have any further curiosity about the install's topology. In gratitude, js


    Quote Originally Posted by jumper View Post
    Okay maybe I was wrong and you understand the difference between grounding and bonding, but your following statement implies to me there was a bit of confusion:



    From that wording I had inferred that a little theory on the subject would be useful to you.

    If I/we seem to be a bit hardcore about correct terminology, it is because if we all do not use the same terms and definitions then confusion results.

    Remember, we are spread out in all the states and also a few countries, so keeping an established common language of terms, definitions, and such is essential for effective communication.

    Also writing out what you actually mean is quite difficult for most of us. What we write is not always what we mean or it is written in a way that can interpreted more than one way.

    And some times one’s brain just goes haywire and the resulting post is a bit whacked. Trust me I know, posted more than one doozy myself. It happens. Most members here are a forgiving lot if one just says “Oops” or “ My bad”.

    Now, as far as your installation is concerned - at this point I think I now have a pretty good idea what you are facing. Later I will post what I percieve and you can correct me as needed.
    Last edited by jumper; 01-08-18 at 01:09 AM. Reason: remove private info

  10. #20
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    solution clarified

    I'm pitching to client cutting those 4 GEC's into his unit and re wiring the 4 disconnects/services with new GEC's run to new ground rods meeting NEC placement rules.

    He's trying to contact building's builder in a last attempt to shed light on what he did.......

    js


    Quote Originally Posted by docj67 View Post
    I reread some of my postings and I see how they could have been misinterpreted!- thx

    I like that this forum IS hardcore about terminology--I will be more precise going forward.

    In the meantime, I'm mostly curious about :

    1) what is an OCPD?

    2) How specifically does running an EGC to a subpanel ground bar violate 250.24(A)(1). I read 250.24(A)(1 several times. My training and experience ( lol ) tells me its wrong irregardless of
    250.24(A)(1) but the verbiage is so damn dense I was unable to make the intellectual link.

    I'm not too concerned about solving the issue but I would like to better understand from an practical POV what the possible issues are from such a whacked build out. If those 4 GEC's aren't bonded to metal framing that is hidden then the whole issue is sorta moot and only worthwhile as intellectual fodder The solution is to snip those 4 GEC's and drop in two new ground rods according to NEC rules.

    I began this dialogue in an attempt to learn what sort of problems could be created by landing service GEC's on a subpanel not part of the services per se. The fix is straightforward: Correct buidling GES and unit GEC's to code. Boom!

    I hope this is clear sir My tele is xxxxxxxxxif u have any further curiosity about the install's topology. In gratitude, js

    Last edited by jumper; 01-08-18 at 01:52 AM.

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