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Separate BLdg grounding

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    Separate BLdg grounding

    my fellow Electrition
    upgraded exist service in gas station
    the new service is located outside of building at the corner of the property

    and three sub panels inside the building

    asking me if all those sub panes need to have main brak
    and grounded individually to a common grounding rod


    If the "service" is really at the property line (i.e., the utility involvement stops there), then the power to the building falls under 225 (outside branch circuits and feeders). 225.30 only allows one feeder to the building (I sincerely doubt this installation would meet any of the "exceptions"). So how is power being brought to the three panels? Are there three separate runs from the service point, within one going to each panel? That would be a violation. Is there one building disconnect that, in turn, feeds all three panels? That would be allowable, and is probably the best option. Are two of the panels each fed via a breaker from the first panel? If so, that first panel would need a main breaker, and the other two could be MLO.

    In any event, the building will need a grounding electrode system. The grounding electrode conductor would be connected to the ground bus associated with the enclosure that includes the building's disconnecting means.

    Please give us more details about the installation.
    Charles E. Beck, P.E., Seattle
    Comments based on 2017 NEC unless otherwise noted.


      What exactly is located at the corner of the property?

      As mentioned as a general rule you can only run one feeder to the building. If what is at the corner of the property is not considered to be a service disconnecting means then you can run multiple service conductors from a single source to multiple 'service disconnecting means' at the building.

      If there is a disconnect at the corner of property but is POCO provided, some AHJ's don't recognize that as the service disconnecting means and you still treat load side conductors as though they are service conductors.

      Details and practices in the jurisdiction are important to answering the questions here.
      I live for today, I'm just a day behind.