Abstract: A system for the transmission of electrical energy between different parts of an electrically conductive structure, and in particular for transmission of power and/or data signals to/from downhole equipment or instrumentation in oil and gas wells. A first layer of electrically insulative ceramic material is deposited on the structure, followed by a series of electrically conductive tracks and a second layer of electrically insulative ceramic material. The tracks which serve for the transmission of power and/or data signals are thus sandwiched between the two ceramic layers, insulated from the structure and the external environment and protected from damage. Each layer is deposited by a thermal spray process such as plasma spraying or high velocity oxy fuel spraying.