A method for detecting an earth fault on a three-phase electric line of an electric network, the method comprising: determining (301; 401; 501; 601; 701; 801) a value of a neutral admittance of the three-phase electric line on the basis of values of a residual voltage of the electric network and a residual current of the electric line; detecting the earth fault on the three-phase electric line on the basis of the determined value of the neutral admittance and one or more predetermined parameter values, characterized in that the one or more predetermined parameter values are given as residual current quantities, as residual power quantities, or as per unit quantities, and in that the detecting of the fault on the three-phase electric line comprises: a) converting (603; 703; 803) the one or more predetermined parameter values from a residual current domain, from a residual power domain, or from a per unit domain into a neutral admittance domain or into a per unit domain of neutral admittance; and comparing (604; 704; 804) in the neutral admittance domain or in the per unit domain of neutral admittance the determined value of the neutral admittance with the converted one or more predetermined parameter values; or b) converting (302; 402; 502) the determined value of the neutral admittance from a neutral admittance domain or from a per unit domain of neutral admittance into a residual current domain, into a residual power domain, or into a per unit domain; and comparing (304; 404; 504) in the residual current domain, in the residual power domain, or in the per unit domain the converted value of the neutral admittance with the one or more predetermined parameter values; and c) detecting (305; 405; 505; 605; 705; 805) the earth fault on the basis of the comparison. determining (301; 401; 501; 601; 701; 801) a value of a neutral admittance of the three-phase electric line on the basis of values of a residual voltage of the electric network and a residual current of the electric line; detecting the earth fault on the three-phase electric line on the basis of the determined value of the neutral admittance and one or more predetermined parameter values, characterized in that the one or more predetermined parameter values are given as residual current quantities, as residual power quantities, or as per unit quantities, and in that the detecting of the fault on the three-phase electric line comprises: a) converting (603; 703; 803) the one or more predetermined parameter values from a residual current domain, from a residual power domain, or from a per unit domain into a neutral admittance domain or into a per unit domain of neutral admittance; and comparing (604; 704; 804) in the neutral admittance domain or in the per unit domain of neutral admittance the determined value of the neutral admittance with the converted one or more predetermined parameter values; or b) converting (302; 402; 502) the determined value of the neutral admittance from a neutral admittance domain or from a per unit domain of neutral admittance into a residual current domain, into a residual power domain, or into a per unit domain; and comparing (304; 404; 504) in the residual current domain, in the residual power domain, or in the per unit domain the converted value of the neutral admittance with the one or more predetermined parameter values; and c) detecting (305; 405; 505; 605; 705; 805) the earth fault on the basis of the comparison. a) converting (603; 703; 803) the one or more predetermined parameter values from a residual current domain, from a residual power domain, or from a per unit domain into a neutral admittance domain or into a per unit domain of neutral admittance; and comparing (604; 704; 804) in the neutral admittance domain or in the per unit domain of neutral admittance the determined value of the neutral admittance with the converted one or more predetermined parameter values; or b) converting (302; 402; 502) the determined value of the neutral admittance from a neutral admittance domain or from a per unit domain of neutral admittance into a residual current domain, into a residual power domain, or into a per unit domain; and comparing (304; 404; 504) in the residual current domain, in the residual power domain, or in the per unit domain the converted value of the neutral admittance with the one or more predetermined parameter values; and c) detecting (305; 405; 505; 605; 705; 805) the earth fault on the basis of the comparison.