An electrosurgical system includes a generator (10) for generating radio frequency power, and an electrosurgical instrument (12) including at least three electrodes. The generator comprises a radio frequency output stage having at least a pair of output lines (60C), and a power supply (66) coupled to the output stage for supplying power to the output stage. The generator also includes a controller (72) capable of varying a radio frequency signal supplied to the output lines, and a switching circuit (62) having three or more output connections (62A, 62B, 62C) each electrically connected with a respective one of the at least three electrodes. This switching circuit is operable to vary the connections between the output lines (60C) and the output connections (62A, 62B, 62C). A switching device (16A, 16B) forming part of the system is operable by the user to send a signal to the switching circuit (62) within the generator in order to vary the electrode or electrodes to which radio frequency power is supplied, the switching device also causing a signal to be sent to the controller (72) such that the radio frequency signal supplied to at least one of the three or more output connections varies depending on the electrode or electrodes to which radio frequency power is supplied. In one arrangement of the switching circuit, one of the electrodes has no direct connection to the output stage of the generator and is connected via a capacitor to another of the electrodes.