An adapter is provided for electrically connecting an interior surface of a conduit and an external surface of a cable. The adapter includes a flat strip extending longitudinally from first to second ends with first and second transverse edges and composed of an electrically conductive and mechanically flexible material. The strip includes a longitudinal ribbon that forms a ring for wrapping around the cable by curling the first and second ends together in a direction transverse to the sheet, and a plurality of first and second incisions from the transverse edges towards the ribbon, the incisions being disposed at respective intervals that correspond to a longitudinally regular pattern. The first incisions form tapering tabs for bending in the direction transverse to the sheet to produce petals that extend radially inward from the ring to engage the cable. The second incisions form peripheral tabs for bending in an opposite direction transverse to the sheet to produce flanges that extend radially outward from the ring to engage the conduit.