Abstract
It is a question of concern if - and how - the vulnerability of the electric power grid and probability of interruptions is increasing as assets are ageing and components are being utilized closer to their limits. These aspects may have severe long-term consequences which it is of vital importance to know more about. The comprehensive data basis in Norway on component faults and end-user interruptions has been explored to reveal trends in the level of quality of supply and the technical condition of the network. The study shows that there has been a considerable reduction in energy not supplied while the number of delivery point interruptions is almost unchanged. However, in the same period there has been a significant increase in the fault rate for temporary faults for overhead lines. This is mainly due to increased focus on registration of automatic breaker re-closure and short interruptions.