A method for detecting a phase-to-earth fault on a three-phase electric line of an electric network, the method comprising: monitoring a zero sequence current on the three-phase electric line and a zero sequence voltage in the electric network; detecting an earth fault in the electric network on the basis of the zero sequence voltage value; determining a difference between the zero sequence current before the earth fault and the zero sequence current during the earth fault; and determining a difference between the zero sequence voltage before the earth fault and the zero sequence voltage during the earth fault, characterized in that the method comprises: determining a neutral admittance, or a quantity indicative thereof, on the basis of a ratio between the difference between the zero sequence currents and the difference between the zero sequence voltages; and comparing the determined neutral admittance, or the quantity indicative thereof, to a predetermined operation characteristic to detect a phase-to-earth fault on the three-phase electric line, wherein the predetermined operation characteristic, when presented on an admittance plane, defines a closed area such that the centre of the closed area is offset from the origin of the admittance plane towards a negative susceptance direction and/or towards a negative conductance direction. monitoring a zero sequence current on the three-phase electric line and a zero sequence voltage in the electric network; detecting an earth fault in the electric network on the basis of the zero sequence voltage value; determining a difference between the zero sequence current before the earth fault and the zero sequence current during the earth fault; and determining a difference between the zero sequence voltage before the earth fault and the zero sequence voltage during the earth fault, characterized in that the method comprises: determining a neutral admittance, or a quantity indicative thereof, on the basis of a ratio between the difference between the zero sequence currents and the difference between the zero sequence voltages; and comparing the determined neutral admittance, or the quantity indicative thereof, to a predetermined operation characteristic to detect a phase-to-earth fault on the three-phase electric line, wherein the predetermined operation characteristic, when presented on an admittance plane, defines a closed area such that the centre of the closed area is offset from the origin of the admittance plane towards a negative susceptance direction and/or towards a negative conductance direction. determining a neutral admittance, or a quantity indicative thereof, on the basis of a ratio between the difference between the zero sequence currents and the difference between the zero sequence voltages; and comparing the determined neutral admittance, or the quantity indicative thereof, to a predetermined operation characteristic to detect a phase-to-earth fault on the three-phase electric line, wherein the predetermined operation characteristic, when presented on an admittance plane, defines a closed area such that the centre of the closed area is offset from the origin of the admittance plane towards a negative susceptance direction and/or towards a negative conductance direction.