A Grounding Electrode Question?

  • 07 Oct 2013 2:58 PM
    Message # 1406958

    An apartment residence has one service drop for two services.  A 200A and a 100A.The 200A consists of a 200A outdoor disconnect with 2/0 SER cable serving a remote panel board.    Its interior grounding terminal block ties its #6 CU to the two ground rods and the #4 Al to the home water piping system.  

    There is a #6 CU grounding electrode conductor from the 100A panel to this terminal block for connection to the existing ground rods.  There is no separate connection for the home water piping system from the 100A panel. Can the connection for the ground rods also serve as the connection to the water piping system for the 100A panel?

  • 10 Oct 2013 8:29 AM
    Reply # 1409272 on 1406958
    I would say that it is all conected togethre and would call it good as long as the conection is of the proper size for the service conductors feeding the service. needs to be sized to 250.66
  • 11 Oct 2013 6:06 AM
    Reply # 1410013 on 1406958
    I will have to respectfully disagree with Steve on this one. If I understand the setting, we have a single service drop or lateral supplying an apartment building with two Services panels. First lets set the record straight, this is a single service with two sets of Service Entrances conductors.

    The two Service panels each must have a GEC run from the interior of the panels to the Grounding Electrode System per NEC 250.64(D)(2). There are no provisions for going through another panel and using the "terminal block" inside the other Service panel.

    I would say that a #6 CU should be run to the water pipe from the 100a. panel and not to the 200a. panel terminal block.

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