Apparatus configured to detect current imbalance between two or more electrical energy distribution elements (4, 10) of an electrical energy distribution network in use, the apparatus comprising: a plurality of temperature sensors (8, 14) each temperature sensor being implemented by a temperature sensing section of an optical fibre (6, 12) each temperature sensing section being arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section, wherein one or more first temperature sensors of the plurality of temperature sensors are configured for thermal contact with a first electrical energy distribution element of the electrical energy distribution network; and one or more second temperature sensors of the plurality of temperature sensors are configured for thermal contact with a second, different, electrical energy distribution element of the electrical energy distribution network; and a detecting unit configured to: determine a first temperature characteristic of the first electrical energy distribution element based on one or more of the optical output signals of the one or more first temperature sensors in use; determine a second temperature characteristic of the second electrical energy distribution element based on one or more of the optical output signals of the one or more second temperature sensors in use; compare the first temperature characteristic with the second temperature characteristic; and detect a current imbalance between the first electrical energy distribution element and the second electrical energy distribution element based on the comparison of the first temperature characteristic with the second temperature characteristic. a plurality of temperature sensors (8, 14) each temperature sensor being implemented by a temperature sensing section of an optical fibre (6, 12) each temperature sensing section being arranged to produce, in response to an optical input signal, an optical output signal indicative of the temperature of the temperature sensing section, wherein one or more first temperature sensors of the plurality of temperature sensors are configured for thermal contact with a first electrical energy distribution element of the electrical energy distribution network; and one or more second temperature sensors of the plurality of temperature sensors are configured for thermal contact with a second, different, electrical energy distribution element of the electrical energy distribution network; and a detecting unit configured to: determine a first temperature characteristic of the first electrical energy distribution element based on one or more of the optical output signals of the one or more first temperature sensors in use; determine a second temperature characteristic of the second electrical energy distribution element based on one or more of the optical output signals of the one or more second temperature sensors in use; compare the first temperature characteristic with the second temperature characteristic; and detect a current imbalance between the first electrical energy distribution element and the second electrical energy distribution element based on the comparison of the first temperature characteristic with the second temperature characteristic. determine a first temperature characteristic of the first electrical energy distribution element based on one or more of the optical output signals of the one or more first temperature sensors in use; determine a second temperature characteristic of the second electrical energy distribution element based on one or more of the optical output signals of the one or more second temperature sensors in use; compare the first temperature characteristic with the second temperature characteristic; and detect a current imbalance between the first electrical energy distribution element and the second electrical energy distribution element based on the comparison of the first temperature characteristic with the second temperature characteristic.