A connection assembly (5) for attaching an electrical apparatus (1) to a bus bar (2). The connection assembly (5) comprises a bolt (6) and a nut (7). The bolt has a head (8) and a shaft (9) with a thread (22) and is configured to be screwed into the nut. The head has an elongated shape so as to allow the head to be introduced into a groove (10) in a bus bar through a slot (11) with the longitudinal axis of the head extending along the slot and thereafter be rotated so as to come into engagement with the groove. Frictional means is provided between the bolt and the nut to provide enough friction between the bolt and the nut for the bolt to rotate with the nut when the nut is turned if the head of the bolt by the surroundings is allowed to rotate essentially freely.
