Accidental arcing grounds on transmission lines constitute the foremost problem to be solved in the transmission of electrical energy over great distances. There has come into use to a limited extent, arcing ground suppressors. This device consists in principle, of a switch in the station which is automatically closed in parallel with the accidental arc at any point out on the system. The parallel path through the switch shunts the current from the arc and thereby extinguishes the arc. This development is not yet completed. This paper gives the results of some experiments on an entirely different device for suppressing accidental grounds¿a device that was first advocated by Prof. W. Petersen of Darmstadt, Germany. The essential part of this new apparatus is a suitable reactor connected between the neutral of the circuit and ground. This reactance is chosen of such a value as to neutralize the capacitance of the circuits when an accidental ground of one phase takes place. Under this acc dental condition the reactor is electrically in parallel with the active capacitances and, by the wellknown fundamental law, the only current that flows to the combination of the inductance and capacitance in parallel is the current necessary to supply the energy loss in the combination. The simplified equivalent conditions are shown in Fig. 4. This energy current can be made very small and it is this relatively small current that passes through the accidental arc to ground.