Abstract: A protective device for electric loads coupled to power circuits, such as the ac power lines inside buildings, has a surge suppressor including a nonlinear surge-protective device in shunt with a resistor-capacitor damping network. This suppressor circuit is well coordinated with a suitable arrester connected to the power lines, for example at the point of entry of ac supply mains into the building. The arrester has a lower voltage protection level than the surge suppressor. This suppressor circuit limits transient voltages at the load and also damps the oscillatory surges that occur in a power connection as described.