Usually the application of exploding wires or foils for current breaking in magnetic energy storage systems is only efficient if the time of current flow through the wire or foil can be limited to around 100/us. A remarkable improvement in voltage generation by slowly explo-ding wires can be achieved by a special containment of the wire. Thus voltages of a few kV per cm wire length can be produced even after some ms of current flow through the wire. The properties of such wires allow a parallel operation with commercially available a. c. breakers with mechanically moved contacts. After a description of such a breaking unit results of tests with “tamped wires” are discussed. At currents of 500 A and a current flow of 1 ms voltages of 140 kV could be generated with copper wires, 95 cm long. Recovery behaviour tests with mainly resistive loads show, that the exploded wire gap could withstand voltages for 50 ms with peak values of 1.3 kV/cm wire length. The voltage steepness generated by the exploded wires depends on the time of current flow through the wire, the wire length, and its containment.