Connecting The Grounding Electrode Conductor To Rebar
November 30, 2005
Q: Where reinforcing steel in a concrete slab that is in contact with the earth is used as a grounding electrode, may the grounding electrode conductor be clamped to a rebar within the concrete or must the connection be made on the outside of the concrete?
A: Generally, the connection of the grounding electrode conductor to the grounding electrode must be accessible. However, 250.68(A) has an exception to this requirement. “Exception – An encased or buried connection to a concrete encased, driven or buried grounding electrode shall not be required to be accessible.”
When the connection will be encased in concrete, an inspection should be made before concrete is poured, and the ground clamp must be marked to indicate that it is suitable for direct burial. A clamp that is suitable for concrete encasement is amrked “direct burial” or “DB.” I would recommend exothermic welding.
Normal practice is to have the general contractor turn up 6 to 12 inches of reinforcing steel rod on both sides of the proposed building if the location of the service is unknown to permit the electrical contractor to connect the grounding electrode conductor to the rebar when electricians arrive at the construction site.
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