A system comprising: an overhead transmission line and a system of smart spacers for overhead transmission line monitoring comprising at least two smart spacers (1, 9) wherein each smart spacer (1, 9) is adapted for bundling at least two conductors of the overhead transmission line and wherein each smart spacer comprises: at least one sensor (4, 10) which is placed on the smart spacer (1, 9), suited for measuring at least one parameter of a condition of the overhead transmission line, and adapted to provide data, which comprises information about the measured parameter, each smart spacer further comprises at least one data transmission unit (5, 11) adapted to receive the provided data from the at least one sensor (4, 10) and from other sensors, to send the provided data and data received from the other sensors to a data receiver, characterized in that each smart spacer further comprising: an energy storing unit that provides energy for operating the at least one sensor and the at least one data transmission unit, wherein any electrical consumers located on each smart spacer such as the data transmission unit (5, 11), the sensor (4, 10), the energy storing unit is powered from the overhead transmission line, wherein the energy storing unit is adapted to provide enough energy to transmit at least data comprising information about a power cut, wherein at least one smart spacer of the system of smart spacers is a slave smart spacer and at least one smart spacer of the system of smart spacers is a master smart spacer, wherein the slave smart spacer is adapted to measure at least one parameter of a condition of the overhead transmission line and to send data which comprises information about the measured parameter to the master smart spacer, and wherein the master smart spacer is adapted to measure at least one parameter of a condition of the overhead transmission line, to receive the data from the slave smart spacer, and to send the data which comprises information about the measured parameters and the data received from the slave smart spacer to an information system. an overhead transmission line and a system of smart spacers for overhead transmission line monitoring comprising at least two smart spacers (1, 9) wherein each smart spacer (1, 9) is adapted for bundling at least two conductors of the overhead transmission line and wherein each smart spacer comprises: at least one sensor (4, 10) which is placed on the smart spacer (1, 9), suited for measuring at least one parameter of a condition of the overhead transmission line, and adapted to provide data, which comprises information about the measured parameter, each smart spacer further comprises at least one data transmission unit (5, 11) adapted to receive the provided data from the at least one sensor (4, 10) and from other sensors, to send the provided data and data received from the other sensors to a data receiver, at least one sensor (4, 10) which is placed on the smart spacer (1, 9), suited for measuring at least one parameter of a condition of the overhead transmission line, and adapted to provide data, which comprises information about the measured parameter, each smart spacer further comprises at least one data transmission unit (5, 11) adapted to receive the provided data from the at least one sensor (4, 10) and from other sensors, to send the provided data and data received from the other sensors to a data receiver, characterized in that each smart spacer further comprising: an energy storing unit that provides energy for operating the at least one sensor and the at least one data transmission unit, wherein any electrical consumers located on each smart spacer such as the data transmission unit (5, 11), the sensor (4, 10), the energy storing unit is powered from the overhead transmission line, wherein the energy storing unit is adapted to provide enough energy to transmit at least data comprising information about a power cut, wherein at least one smart spacer of the system of smart spacers is a slave smart spacer and at least one smart spacer of the system of smart spacers is a master smart spacer, wherein the slave smart spacer is adapted to measure at least one parameter of a condition of the overhead transmission line and to send data which comprises information about the measured parameter to the master smart spacer, and wherein the master smart spacer is adapted to measure at least one parameter of a condition of the overhead transmission line, to receive the data from the slave smart spacer, and to send the data which comprises information about the measured parameters and the data received from the slave smart spacer to an information system.