The invention relates to a device (1) for connecting a first and a second busbar (14, 15), which busbars (14, 15) are hollow and aligned with each other, the device comprising: • - an electrically conducting expansion member (2) for arrangement inside the first busbar; • - displacement means (3) for displacing the expansion member (2) in axial direction from the first busbar (14) at least partially into the second busbar (15); and • - driving means (4) for driving the displacement means and for driving the expansion of the expansion member (2).