60 and consequently forms a peripheral border 64 in the plate 62 are two openings 66 which serve for mounting the first insulating element 24 on the second insulating element 28 these openings are delimited by webs 68 which in the same way as the side wall 60 protrude orthogonally from the plate 62 the webs 68 carry three flat portions parallel to the plate 62 in which there are a further three openings 70 by way of which the second insulating element 28 can be mounted on the base 12 the openings 66 70 are spaced equally apart and or lie on one line the spade shaped portion 32 comprises the insulating plate 46 which is connected by way of the orthogonal side wall 72 to the plate 62 which at its end is widened in a t like manner the side walls 72 surround the insulating plate 46 in a u shaped manner fig3 shows the earthing switch 10 schematically in an open position a half closed position a contacting position and a closed position from left to right in the closed position and in the open position the earthing switch 10 is kept in this position by the locking device 42 in that the locking pin 50 engages in a respective clearance 74 in the locking disk 52 the actuator 48 may.