Patent ID: 7364203

Claim:
An electrical isolation connector subassembly for interconnecting adjacent tubular drill rods of a drilling system used in drilling bore holes in earth formations, said connector subassembly comprising: a mandrel, wherein said mandrel is adapted at one end to connect to a first tubular drill rod; a housing, wherein said housing is adapted at one end to connect to a second tubular drill rod; a conductive ring located on an external surface of said connector subassembly; a plurality of insulator sleeves each having an L-shaped cross-section; said mandrel and said housing being electrically continuous; said conductive ring being electrically isolated from said mandrel and said housing by said insulator sleeves, said insulator sleeves being arranged one with the long arm of the L-shaped cross-section extending between the housing and the conductive ring and the other with the long arm of the L-shaped cross-section extending between the housing and the conductive ring with the short legs of the L-shaped arm cross-section of the respective insulator sleeves being sandwiched between the conductive ring and adjacent opposed faces of the subassembly, providing an exterior gap having a width less than 50 cm; and an electrode assembly that engages said conductive ring wherein said electrode assembly is electrically isolated from said mandrel and said housing, said electrode assembly being positioned within openings in said mandrel wherein said openings extends perpendicular to the longitudinal axis of the electrical isolation connector subassembly.