Abstract
The estimation of power supply interruption costs was performed in Latvia in 2012, in the framework of a survey study (the first officially recognized study of interruption costs in Latvia since restoration of Independence in the early 90’s). The survey involved ~ 3000 end users, which are classified as the major electrical energy consumers in the country. As a result, the customer damage functions (CDFs) and the functions of cost deviations depending on the interruption occurrence time have been created. The study is unique not only for Latvia, but also for the whole Baltic region. The information obtained is usable for improving the quality of supply regulation (also known as Performance Based Regulation (PBR)) and for planning and running the power networks.