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About 10 years ago we had a new meter-main installed upgrading to 200A service from 100A at a new service entrance location (closer to the street) for a 1951 daylight ranch house. At the time they ran a new earth ground (#6, I think?) to at least one location.

Recently I found an old #12 earth ground connected to a rod on the opposite side of the house from service entrance. I tested it with a current clamp with only 0.001 A is flowing, so far so good. Who knows if there are any other grounds around that I've not yet discovered.

What would be best, and why?

  • Leave it as is?
  • Disconnect it?
  • Run a bigger ground to this newly discovered earth ground?
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  • You might consider finding where the other end of the wire goes. You have a sensitive current clamp to be able to read that low of current.
    – Gil
    Sep 30 at 22:32
  • @Gil, it goes into the garage and then into a wall...so except that its clearly a ground, I'm not sure where it goes. More than likely it ties to some plug somewhere that is grounded, but I can only guess.
    – KJ7LNW
    Sep 30 at 22:56
  • @KJ7LNW -- can you find where it leads? It might be a communications grounding rod... Oct 1 at 1:01
  • Unless it's in the way of some current project, why worry about it?
    – FreeMan
    Oct 1 at 15:04
  • @FreeMan, it goes through a 1/2" conduit that will be filled with 3x#8's so would like to ground it to the rest of the system but wasn't sure the best practice here. The conduit is short through a concrete slab and hard to replace. I can see both ends of the ground, but the ground through the 1/2" conduit, but it then disappears under a silplate and into an existing wall.
    – KJ7LNW
    Oct 1 at 23:02
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Separate grounds are allowed when they originate from the same service panel.

In this case the least expensive option would be to put the #12 in a box and make a connection with another number 12 or larger and connect to the grounding electrode for the new panel or any other grounded circuit that is grounded #12 or larger.

This has only been code for a few cycles but is acceptable. If you tied the alternate rod with the #6 wire to the original rod or electrode system or at the panel ( the electrode system is within 5’ of the foundation entrance that would be acceptable as a second electrode). the #12 should be removed from the rod as mentioned.

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