There are 29,000km of high voltage overhead transmission cables in the UK, operating in severe conditions of heat and cold, moisture, voltage stress, wind induced vibration, overloads and structural fatigue, all of which can cause catastrophic failure. The MOSAIC project aims to prototype a novel method of combined monitoring and enhancement of the structural health of these cables, more technically effective, cost effective and safer than existing passive monitoring techniques i.e. infra-red and visual imaging using helicopters and human inspectors. In the MOSAIC technology one sensor module, in a fixed location on a cable and self-powered by inductive harvesting of energy from the cable, will permanently and in real time monitor a cable to: (1) Measure vibrations, which are a major cause of cable fatigue, and actively cancel them through automatic electromechanical means. (2) Actively detect early signs of cable fatigue and track its growth using long range guided ultrasound, which can access cable areas impossible with infrared and visual sensing. (3) Wirelessly transmit essential data including cable location to a base station, for instant maintenance decision making.