A continuous number 3/0 AWG bare copper conductor is embedded within a concrete foundation in direct contact with earth, maintaining a minimum twenty-foot length. The conductor routes upward through a rigid non-metallic conduit to connect to the main building reference ground bus. A dry gravel bed or vapor barrier is prohibited beneath the direct-contact concrete. The conductor is positioned between one inch minimum and two inches maximum from the soil interface and must remain continuous while coordinating with structural requirements.
MAIN BUILDING REFERENCE GROUND BUS RIGID NON-METALLIC CONDUIT CONCRETE FOUNDATION IN DIRECT CONTACT IN EARTH. DRY GRAVEL BED OR VAPOR BARRIER PROHIBITED 20 FEET MIN. #3/0 AWG BARE COPPER CONDUCTOR 2"MAX.1"MIN. SLAB CONSTRUCTION (SEE STRUCTURAL DETAIL) #3/0 AWG BARE COPPER, 1" MIN. 2"MAX FROM SOIL. CONDUCTOR SHALL BE CONTINUOUS; COORDINATE WITH STRUCTURAL. UFER GROUNDING ELECTRODE DETAIL
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