Method of manufacturing a ground apparatus and ground apparatus comprising an aluminum nut (16) having an internal thread and adapted to clamp an eyelet (28) of an electrical conductor on a corresponding contact area of the stud (12), wherein the nut (16) has at least one coating (30) which contains at least zinc, characterized in that the coating further comprises tin, in that the coating consists of an acid tin-zinc electroplating on the aluminum nut (16) and is such that the tin is between 60 and 80% by weight of the coating and the tin-zinc coating forms a layer with an average thickness of from about 5 to 16 microns.