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Thread: Multiple grounding electrodes -- connecting wire sizes

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    Multiple grounding electrodes -- connecting wire sizes

    The following is from a code panel yesterday:

    My grounding electrode system consists of a water pipe, a UFER, and a ground rod. My service conductors are 500kcmil copper. Can I run a 1/0 CU grounding electrode conductor to the water pipe, then a #4 copper conductor from the water pipe to the UFER, then a #6 copper from the UFER to the ground rod?

    The answers were yes and no. What do you guys think?

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    What was the reason for the no, sounds legal.

    Last edited by jumper; 04-25-12 at 10:53 AM.
    "Electricity is really just organized lightning." George Carlin


    Derek

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    Quote Originally Posted by fmtjfw View Post
    The following is from a code panel yesterday:

    My grounding electrode system consists of a water pipe, a UFER, and a ground rod. My service conductors are 500kcmil copper. Can I run a 1/0 CU grounding electrode conductor to the water pipe, then a #4 copper conductor from the water pipe to the UFER, then a #6 copper from the UFER to the ground rod?

    The answers were yes and no. What do you guys think?
    My answer would be yes. However, the #6 would have to be protected in some way.
    Bob

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    Quote Originally Posted by petersonra View Post
    My answer would be yes. However, the #6 would have to be protected in some way.
    I would imagine that from an UFER to a rod would most likely be buried in dirt and not subject to damage.
    "Electricity is really just organized lightning." George Carlin


    Derek

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    Engineer's answer

    Quote Originally Posted by jumper View Post
    What was the reason for the no, sounds legal.

    The no answer came from an engineer on the panel. He said that all conductors needed to be 1/0 since 250.66(A)&(B) both stated "that portion of the conductor that is is sole connection to the grounding electrode" invalidated the two smaller conductor exceptions. Basically that the #4 conductor had to carry not only the current to the UFER but also to the ground rod. He didn't extend that argument to the 1/0 since the table said it was sufficient for any GEC.

    His argument depends on what "sole" means.

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    Quote Originally Posted by fmtjfw View Post
    The no answer came from an engineer on the panel. He said that all conductors needed to be 1/0 since 250.66(A)&(B) both stated "that portion of the conductor that is is sole connection to the grounding electrode" invalidated the two smaller conductor exceptions. Basically that the #4 conductor had to carry not only the current to the UFER but also to the ground rod. He didn't extend that argument to the 1/0 since the table said it was sufficient for any GEC.

    His argument depends on what "sole" means.
    The fact that since you have a water pipe and UFER GES in place means that the whole rod connection(s) is nothing but extra.

    EE is wrong IMO. I believe the purpose of this section is more in line with something like that you cannot run a #4 to a UFER and then then a larger jumper, ie: #2 to a ground ring, and be compliant.
    "Electricity is really just organized lightning." George Carlin


    Derek

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    Quote Originally Posted by jumper View Post
    I would imagine that from an UFER to a rod would most likely be buried in dirt and not subject to damage.
    the dirt could well be the protection means IMO.
    Bob

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    Quote Originally Posted by fmtjfw View Post
    The no answer came from an engineer on the panel. He said that all conductors needed to be 1/0 since 250.66(A)&(B) both stated "that portion of the conductor that is is sole connection to the grounding electrode" invalidated the two smaller conductor exceptions. Basically that the #4 conductor had to carry not only the current to the UFER but also to the ground rod. He didn't extend that argument to the 1/0 since the table said it was sufficient for any GEC.

    His argument depends on what "sole" means.
    I think he does not understand English very well.
    Bob

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    Quote Originally Posted by petersonra View Post
    the dirt could well be the protection means IMO.
    In that case, I agree.
    "Electricity is really just organized lightning." George Carlin


    Derek

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