An electrical plug-and-socket connection part includes socket housings which assemble together to form the plug-and-socket connection part. Each socket housing includes longitudinally extending compartments for holding contact elements. Each socket housing has an associated locking bar arranged to slide in a direction transverse to the compartments for locking the contact elements in the compartments. Upon the socket housings being connected with one another the locking bars engage with one another such that locking motion of one of the locking bars is transferred to the other locking bars. The locking bars may be fixed in a preliminary latched position against their respective socket housings before the socket housings are connected together. One of the socket housings may include an unlocking mechanism for removing the locking bar of an adjacent socket housing from the preliminary latched position against the adjacent socket housing after the socket housings have been connected together.