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  1. #1
    Join Date
    Mar 2007
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    Iron Mountain, MI
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    41

    Default Underground Service

    Hi:

    Can it be assumed that an underground electric service is properly grounded?

    Would you write up no ground at the water supply entry pipe, in a house with an underground electric service?

    Attached is a photo of the water service pipe with no ground wire clamped to it (the white thing is a sock).

    Thanks,
    Joe

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  2. #2
    Join Date
    Jan 2011
    Location
    Utah
    Posts
    112

    Default Re: Underground Service

    Don't assume any circuit is grounded. It is unlikely that a utility would not ground a transformer. There should be a copper ground lead in the Meter Base, connected to a ground rod. That ground rod will likely be inside the transformer enclosure. The service panel may be connected to a ground rod. The NEC allows either (rod or water pipe) to be used. In my area, both are required by local authority. There is a simple, non-technical way to test the ground circuit. Jumper any 15a or 20a circuit breaker to the ground bus. If the ground circuit is effective, the breaker will trip. Nothing will be melted or blackened, just a slight spark, and the breaker trips.


  3. #3
    Join Date
    Feb 2009
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    On The Mason-Dixon Line
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    577

    Default Re: Underground Service

    [quote=Jimmy Roberts;166158]Don't assume any circuit is grounded. It is unlikely that a utility would not ground a transformer. There should be a copper ground lead in the Meter Base, connected to a ground rod. That ground rod will likely be inside the transformer enclosure. The service panel may be connected to a ground rod. The NEC allows either (rod or water pipe) to be used. In my area, both are required by local authority.

    The NEC requires that when there is a metelic underground water service with 10' or more in contact with the ground It MUST be used as a grounding electrode. There is no option or exception to this


    There is a simple, non-technical way to test the ground circuit. Jumper any 15a or 20a circuit breaker to the ground bus. If the ground circuit is effective, the breaker will trip. Nothing will be melted or blackened, just a slight spark, and the breaker trips.

    DO NOT DO THIS !!! This is a dangerous action. Why would anyone create a direct short to ground this way. Do you have any idea how many amperes you are causing to flow through that breaker prior to it tripping
    Very bad unprofessional advice


  4. #4
    James Duffin's Avatar
    James Duffin Guest

    Default Re: Underground Service

    [quote=ken horak;166163]
    Quote Originally Posted by Jimmy Roberts View Post
    Don't assume any circuit is grounded. It is unlikely that a utility would not ground a transformer. There should be a copper ground lead in the Meter Base, connected to a ground rod. That ground rod will likely be inside the transformer enclosure. The service panel may be connected to a ground rod. The NEC allows either (rod or water pipe) to be used. In my area, both are required by local authority.

    The NEC requires that when there is a metelic underground water service with 10' or more in contact with the ground It MUST be used as a grounding electrode. There is no option or exception to this


    There is a simple, non-technical way to test the ground circuit. Jumper any 15a or 20a circuit breaker to the ground bus. If the ground circuit is effective, the breaker will trip. Nothing will be melted or blackened, just a slight spark, and the breaker trips.

    DO NOT DO THIS !!! This is a dangerous action. Why would anyone create a direct short to ground this way. Do you have any idea how many amperes you are causing to flow through that breaker prior to it tripping
    Very bad unprofessional advice
    I have to agree. Most residential breakers have a fault current rating of 10,000 amps. If the circuit from the power company has a higher fault rating than that the beaker can explode. I see no reason to test out the theory that a 10k rating is adequate by creating an intention short.

    Also to the OP....as far as I know the same grounding requirements apply to both overhead and underground services. Once the wires gets to the meter base from the power company all is the same from the bottom of the meter base onward.


  5. #5
    dana1028's Avatar
    dana1028 Guest

    Default Re: Underground Service

    Quote Originally Posted by Jimmy Roberts View Post
    There is a simple, non-technical way to test the ground circuit. Jumper any 15a or 20a circuit breaker to the ground bus. If the ground circuit is effective, the breaker will trip. Nothing will be melted or blackened, just a slight spark, and the breaker trips.
    I heartily agree with the other 2 posters admonishing this practice.

    I will add - you are VERY confused about grounding and bonding. Even if you did what you are suggesting [create a fault situation....and thus trip a breaker] - it proves NOTHING with respect to the GROUNDING of a service.

    GROUNDING is about lightning protection...i.e. taking a lightning strike to ground...away from your structure...read section 250.4(A)(1) of the NEC....there is NOTHING about a grounding electrode [ground rod] or grounding electrode conductor that is designed to clear faults [i.e. 'trip' a breaker].

    Breakers 'trip' under a fault condition because of proper equipment 'bonding' of components...to 'create an effective ground fault current path' back to the service equipment...and thus to the utility transformer....and then back to the service equipment...to the breaker that is protecting the faulted circuit...and thus the 'tripped' breaker.........this fault current DOES NOT go to ground! [ground rod/water pipe].

    Essentially: We GROUND to protect from lightning, line surges [NEC 250.4(A)(1), and
    We BOND to open the circuit over current protection devices [circuit breaker/fuse - see 250.4(A)(3), (4), (5)].


  6. #6
    Join Date
    Mar 2007
    Location
    Ormond Beach, Florida
    Posts
    26,252

    Default Re: Underground Service

    I have to agree with Ken, James, and Dana - Jimmie gave very bad advice.

    Jerry Peck, Construction / Litigation Consultant
    Construction Litigation Consultants, LLC ( www.ConstructionLitigationConsultants.com )
    www.AskCodeMan.com

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