The basic unit (1) of a
switchgear assembly has a ring
busbar (2), four outgoers (7, 8, 9, 10) which are connected to the
busbar (2) via a respective
isolator (3, 4, 5, 6), as well as two commutation switching elements (11, 12) and two disconnection elements (13, 14), which are arranged in the
busbar (2) and are closed during normal operation. Each outgoer (7, 8, 9, 10) is connected via a commutation switching element (11, 12) to one of the adjacent outgoers, and via a disconnection element (13, 14) to the other of the adjacent outgoers. The basic unit (1) also has a third commutation switching element (15), which is closed during normal operation and is connected in series both with the first commutation switching element (11) and with the second commutation switching element (12). Each disconnection element (13, 14) is thus bridged by a parallel current path comprising two commutation switching elements (11, 15; 12, 15) which are in each case connected in series. The commutation switching elements (11, 12, 15) are designed for carrying the rated current and, briefly, a fault current, but are not designed for disconnection of fault currents. In contrast, the disconnection elements (13, 14) are designed for fault current interruption, but not for carrying the rated current.