Residual current circuit breakers NOCLE-125 RCBO are used for protection against indirect touching of parts under voltage, for prevention of lasting voltage on earthed parts whitch should appear because of a defect in the electrical installation and for protection against direct contacts of parts under voltage in case of In<30mA.Residual current circuit breakers can be used in TN-S,TT and IT network systems or with other words in all systems where neutral and protective conductor are separated (VDE 0100 Teil 410).