An uninterruptible power supply having a controllable leakage current is disclosed. The leakage current is controlled by adjusting a switching speed (i.e., dV/dt rate) of switches in the output inverter (i.e. DC-AC converter stage). Leakage current can be reduced by reducing the switching speed (dV/dt rate) of the output inverter switches. In one embodiment, leakage current is held constant or moderated as output power decreases by reducing the switching speed (responsive to leakage current) as output power decreases. The switching speed can be adjusted by adjusting the gate resistance or gate voltage. Increasing the gate resistance or decreasing the gate voltage will cause a reduction in the switching speed, and increase in leakage current. Conversely, reducing the gate resistance, or decreasing the gate voltage will cause an increase in switching speed, and increase in leakage current. The present invention is applicable to any uninterruptible power supply having output inverter switches.