The evaluation of the costs associated with the interruptions of the supply with the electrical energy is very important in planning of power system operation and structure using the cost–benefit approach. Many detailed studies have been performed in the past in order to evaluate the supply curtailment effects with particular concern about residential customers. The consequences of supply curtailments have been assessed using surveys asking the customers to perceive the costs to households for a fixed scenario regarding the season of the year, day and time of interruption occurrence. This paper makes an attempt to enhance this analysis by treating the household activities as flows of events overlapping by chance with supply interruptions. Household activities have been modeled separately for various seasons of the year during weekdays and holidays in order to evaluate the interruption consequences in all possible circumstances. These data have been then used to determine the expected customer interruption costs on annual base.