It is necessary to eliminate immediately double-ground faults in feeder cable networks in order to avoid cable sheath overheating and its insulation damaging. To achieve this, the special protection is proposed which "takes into account" the first stage of double-ground fault, namely, "marks" the line with single-phase earth fault and later, when one more phase of this very line or of some other line of the network becomes faulty to earth, the protection instantly switches off one damaged line.