Share grounding rod in PV/Mains hybrid?

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  • max2k
    Junior Member
    • May 2015
    • 819

    #16
    Originally posted by Gdwats

    I see, that is what i have, but nothing I've done is grounded or connected in any way, to the house. Yes, the bonding ground wire is awg4, a but overkill.
    It's not the presence of the house is what's important but non 0 distance between the rods- any such distance would make rods under different potential during the strike due to potential gradient (those concentric circles on the graphic). Then if both wires coming into anything you might get tens of kV difference between them. Bonding directly avoids this problem and all your equipment gets under the same potential being connected to a single point.
    Last edited by max2k; 09-25-2017, 05:37 PM.

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    • Gdwats
      Junior Member
      • Jul 2017
      • 207

      #17
      The odds of me understanding grounding configurations are about as good as me being struck by lightning. How can all my stuff be grounded to a single point when that point itself is bonded to another point, the second rod, 6 feet away. Unless the entire 6' x 8' bonded structure is considered one point. What is the "point"?
      900W, 40A MPPT, 230AH FLA,24V Samlex 1500W

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      • max2k
        Junior Member
        • May 2015
        • 819

        #18
        Originally posted by Gdwats
        The odds of me understanding grounding configurations are about as good as me being struck by lightning. How can all my stuff be grounded to a single point when that point itself is bonded to another point, the second rod, 6 feet away. Unless the entire 6' x 8' bonded structure is considered one point. What is the "point"?
        take a look at the screenshot posted earlier. When lightning strikes it creates concentric circles around with equivalent potentials, pretty much like normal map shows those lines of the same heights. Now if you happen to drive your rods between any of those 2 lines you'd get difference in potential in other words voltage in the range of possibly tens of kV. Solution is simple- bond those 2 rods with wire so the current 'equalizing' those kVs would flow through that wire and the wire will 'tie' up 2 rods closer in potential. Your equipment can be connected anywhere to this 'system' just make sure it's a single point. In case of a strike equipment will get under that point high potential but since it's the only point all equipment will be under the same tens of kVs potential (0 difference) and will remain safe.

        As opposite to this consider running separate wires from each of your rods and connecting them to your equipment. In case of the strike equalizing current will come to your equipment first and then go back to the second rod. This is dangerous as it can create significant voltages along its way now inside/on the case of your equipment. We're talking of short burst of current in possibly kA range capable of creating voltage spikes in kV range.

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        • Gdwats
          Junior Member
          • Jul 2017
          • 207

          #19
          It is sinking in, thank you. I think i was concerned about my general system grounding, and not thinking about lightning protection. But it sounds like I may have both, to a degree, with the dual rod setup depending on where lightning strikes.
          900W, 40A MPPT, 230AH FLA,24V Samlex 1500W

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