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The switching chamber for a heavy-duty circuit breaker which can be filled with a quenching gas has a first arcing contact piece (1) and a second arcing contact piece (2), of which at least one (1; 2) can be moved by means of a drive. An arc (4) may burn between the contact pieces (1, 2). A heating chamber (11) is used for temporarily storing quenching gas heated by the arc (4). An insulating nozzle (5) has a throat (6), which is used for guiding a quenching gas flow and is connected to the heating chamber (11). During an opening operation, a maximum relative speed V12,max of the two arcing contact pieces (1, 2) in relation to one another is reached which is at least 1.3 times as great as a relative speed v12,c of the two arcing contact pieces (1, 2) which is required for capacitive switching. In the case of a single-chamber heavy-duty circuit breaker, in particular the following applies for the maximum relative speed V12,max- V12,max ^ 23 * UN*p* f / (Ecrit'Po) f wherein UN is the rated voltage of the heavy-duty circuit breaker if the latter is in the form of a single-chamber heavy-duty circuit breaker, p is the pole factor of the heavy-duty circuit breaker, Ecrit is the threshold field strength for discharges of the quenching gas, and p0 is the filling pressure of the quenching gas, and f is the system frequency for which the switching chamber is designed. (Figure 1)