Abstract: In an electric coupling device for covering two ranges of current intensities with one and the same casing, each terminal has a stationary conductive strip (28) and a movable yoke (48) which are mounted within a housing of the casing so as to clamp a conductor (51). The housing can also accommodate a more bulky cage-type connector. In order to guide the movable components (42, 48) of the yoke connector and the conductor (51) at the time of introduction, an adapter (52) is fitted within the housing. The adapter surrounds the yoke connector so as to close the clamping zone laterally between the conductive strip (28) and the yoke (48) and to prevent rotation of the yoke. An abutment face (61) limits the relative spacing of the yoke (48) and the strip (28) while a well (59) guides the screw head. A masking panel (71) of the adapter limits the size of the opening (17) to the strict minimum required for introduction of the conductor.