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.