A system for heat ablation of tissue, the system comprising a radiofrequency source configured to supply RF energy to at least two electrodes for treating tissue, at least one return electrode configured to return the RF energy to the radiofrequency source, a controller configured to sequentially apply the RF energy to each of the at least two electrodes for a pre-determinable period of time and circuitry configured to switch the RF energy to an internal load. The RF energy is applied simultaneously to the internal load and at least one of the at least two electrodes. The controller is configured to apply the RF energy to the next electrode in the sequence when the amount of time the applied RF energy is off is greater than a predetermined minimum off time.