Adequate assessment of the economic damage caused by power supply interruption of consumers allows to analyze risks of these events, to create safe, reliable supply of energy resources that represents a fundamental factor for ensuring economic stability of country and its regions development. The analysis of domestic and foreign methodical approaches to assessment of the damage caused by power supply interruption showed that the corresponding methodical approach is developed insufficiently fully now. It determines relevance of this research. The structure of direct and indirect damage caused by power supply interruption of consumers is proved. Basic provisions of developed techniques of assessment of damage which include a method of detailed calculation of components of damage (real loss, social economic losses, ecological damage, indirect losses) for the happened accident, the technique of forecasting of damage based on use of standard scenarios of accidents and also a technique of forecasting of damages with use of specific indicators of unplanned costs are described. Typical scenarios of accidents are created on the basis of the analysis of the regulating documentation and statistical data on primary groups of consumers of the gas industry (production facilities, transport, storages, reprocession and auxiliary objects). The damage assessment with use of specific indicators allows to consider the size of the disconnected capacity, duration of an interruption and duration of recovery of power supply. Comparison of the received values of damage from a power supply interruption of the gas industry objects with real values of damages from accidents allows to speak about adequacy of developed methods. © 2019 European Safety and Reliability Association. Published by Research Publishing, Singapore.