An SF6 gas-isolated switch installation for several switchboard sections, each with a three-pole separating switch and an earthing device. A switchboard section is equipped with a separating switch designed as a transformer switch. This can be a load-break switch, whose phases are combined with cutouts, or a load-isolating breaker. The switch installation has for the support of mobile switch contacts and the connection of cables and/or cutouts appropriate lead-throughs in the housing walls and switch shafts mounted on said walls, as well as omnibus bars for the fixed contact of phases L1, L2 and L3, and individual phase quenching devices directly connected to the omnibus bars (9). The quenching devices of the load-break switches that do not function as as transformer switches are equipped with sheet steel quenching chambers. Breaking ability must be enhanced with no extra space requirement. For this purpose blow-out coils (13, 13a) are introduced according to an arrangement which when in off position meets the requirements for a disconnected section, with a contact arrangement corresponding to the remaining load-break switches for the three phases of the switch designed as a transformer switch.