The impact of power interruption on the modern society, who uses electricity almost in every aspect of life, is very severe. During power interruption, the daily routine activities of the consumers especially the industrial sectors that depend mainly on electricity will be paralyzed. The economic impact of power interruption on Yes Brands Foods & Beverages Plc and Oxford Amalgated plc were assessed. The interruption duration and frequency of yes plc are 20.89 hrs/month and 48.5times/month respectively. In addition, the interruption duration and frequency of the oxford plc are 29.05hrs/month and 38.33times/month respectively. The mixed method research approach and case study were used to analyze the case deeply in a given bounded time by collecting relevant data through both primary data sources (interview, observation and discussion) and secondary data sources (document reports and review). The preventive cost method (revealed preferences method) and the production function cost estimation methodologies were used to analyze the power interruption unit cost of yes plc and oxford plc respectively. The results indicated that the power interruption unit cost of yes and oxford plc are 14.78birr/kwh & 22.13birr/kwh respectively. The main indentified causes of power interruption of the industries are short circuits, earth faults, and operational request. The causes for short circuits and earth faults at the substation can be minimized by inspecting the power system regularly and replacing the damaged equipments, insulators, protective devices etc. The industrial sectors can mitigate the cost incurred due to power interruption by arranging backup system and facilities. Substation feeders' rearrangement can reduce the cost incurred by oxford plc due to power interruption by 84%.