A system for determining an impedance of an electrical network, wherein the electrical network comprises a common root part, a first branch (Branch 1) and a second branch (Branch 2), wherein the first branch and the second branch are both coupled to the common root part of the electrical network, the system comprising: an electrical network monitoring unit configured to: determine a plurality of electrical measurement data sets, each electrical measurement data set comprising: a measure of current (I 0 ) through the common root part, a measure of current (I 1 ) through the first branch, a measure of current (I 2 ) through the second branch, a measure of voltage (V 0 -V 1 ) across the first branch and common root part, and a measure of voltage (V 0 -V 2 ) across the second branch and common root part, wherein the measure of voltage across the first branch and the common root part (V 0 -V 1 ) is a difference between a voltage at the common root part (V 0 ) and a voltage at the first branch (V 1 ), and wherein the measure of voltage across the second branch and the common root part (V 0 -V 2 ) is a difference between a voltage at the common root part (V 0 ) and a voltage at the second branch (V 2 ); define, using the plurality of electrical measurement data sets, a set of simultaneous equations that define a relationship between the measures of current through the first branch (I 1 ), the second branch (I 2 ) and the common root part (I 0 ), the measure of voltage across the first branch and the common root part (V 0 -V 1 ) and the measure of voltage across the second branch and the common root part (V 0 -V 2 ), and an impedance of the first branch (X line20 ), an impedance of the second branch (X line30 ), and an impedance of the common root part (X line10 ); and determine, by solving the set of simultaneous equations, one or more of: the impedance (X line10 ) of the common root part, the impedance (X line20 ) of the first branch, the impedance (X line30 ) of the second branch. determine a plurality of electrical measurement data sets, each electrical measurement data set comprising: a measure of current (I 0 ) through the common root part, a measure of current (I 1 ) through the first branch, a measure of current (I 2 ) through the second branch, a measure of voltage (V 0 -V 1 ) across the first branch and common root part, and a measure of voltage (V 0 -V 2 ) across the second branch and common root part, wherein the measure of voltage across the first branch and the common root part (V 0 -V 1 ) is a difference between a voltage at the common root part (V 0 ) and a voltage at the first branch (V 1 ), and wherein the measure of voltage across the second branch and the common root part (V 0 -V 2 ) is a difference between a voltage at the common root part (V 0 ) and a voltage at the second branch (V 2 ); define, using the plurality of electrical measurement data sets, a set of simultaneous equations that define a relationship between the measures of current through the first branch (I 1 ), the second branch (I 2 ) and the common root part (I 0 ), the measure of voltage across the first branch and the common root part (V 0 -V 1 ) and the measure of voltage across the second branch and the common root part (V 0 -V 2 ), and an impedance of the first branch (X line20 ), an impedance of the second branch (X line30 ), and an impedance of the common root part (X line10 ); and determine, by solving the set of simultaneous equations, one or more of: the impedance (X line10 ) of the common root part, the impedance (X line20 ) of the first branch, the impedance (X line30 ) of the second branch. <EOS>