Mechanical locking at a plug connection between an electric switch and a plug connector

A mechanical locking on a plug connection between an electrical switch forming one part and a connecting plug forming another part, comprises a pin-shaped extension provided on one of the parts, a matching depression on another of the parts in which the extension engages, the depression having a side wall extending parallel to a longitudinal axis of the plug connection and provided with an inwardly extending blocking lug, a blocking spring having a pin-shaped extension engageable with the blocking lug and having a blocking extension extending outwardly toward the blocking lug and an inwardly directed blocking extension engageable in a recess which can be brought in alignment with a depression of the pin-shaped extension. A housing of one the connecting plug and the switch and has an engagement slot located adjacent to a free end of the blocking spring and provided for a pin-shaped tool with which the blocking projection can be released from a locking connection with the blocking lug only in such a position of the switch in which the blocking extension of the blocking spring is located opposite to the recess of the pin-shaped extension for a blocking engagement and releaseable from locking with the blocking lug, so that the switch and the connecting plug can be pulled out and withdrawn from one another.