Grounding Rod Connections
December 7, 2005
Q: Am I permitted to connect two ground rods spaced eight feet apart to the service without running the grounding electrode conductor from one rod to the other? What parts of the NEC would allow or not permit such an installation?
A: Yes, you are permitted to run individual grounding electrode conductors from each ground rod to the service grounded conductor terminal in the service disconnecting means. The size of the grounding electrode conductor from each ground rod cannot be smaller than 6 AWG copper.
A single 6 AWG copper conductor is also permitted. It can be run from one rod to the other and then to the service or metal cold water pipe within 5 feet of where the pipe enters the building. The exception to this rule allows the connection to be made beyond 5 feet in commercial and industrial buildings under limited conditions [See 250.52(A)(1)].
If the ground rods are the only grounding electrodes for the service because there is no buried metal water pipe and the building structural steel is not effectively grounded, a single grounding electrode conductor is permitted to run from one rod to the other and then to the grounded service conductor, or two separate grounding electrode conductors (one from each rod) are permitted to be connected to the grounded (neutral) service conductor in the service disconnecting means. The part that allows this is 250.64(F).
Methods that are suitable for connecting grounding electrode conductors to grounding electrodes and grounded circuit conductors are outlined in 250.70.
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