The invention relates to a surge protected power supply for feeding a device with electrical energy. The power supply includes a surge protection device SPD connected in series with a controllable switch where this series connection is connected between two current conductors of the power supply. The power supply further includes a device for determining a comparison voltage such that the comparison voltage is in some form indicative of a surge voltage present at the input of the power supply. This comparison voltage then is compared to a threshold. If the comparison voltage is higher than the threshold, the controllable switch is closed such that the SPD in series with the switch is effectively connected between the two current conductors to divert the surge current through the SPD. If the comparison voltage is lower than the threshold the switch remains open.