Observed changes in residential and commercial customer interruption costs in the Pacific Northwest between 1989 and 1999

In 1989, the Electric Power Research Institute and Bonneville Power Administration conducted pioneering surveys of the interruption costs experienced by residential and commercial and industrial customers in the Pacific Northwest. In early 1999, Puget Sound Energy (PSE) surveyed its customers using statistical sampling techniques and outage cost measurement procedures nearly identical to those used in the BPA/EPRI study. This paper compares the results obtained from those two outage cost surveys focusing on the differences in costs that was observed between them. The results of the comparison indicate that customer interruption costs have increased dramatically for residential customers. Comparison of interruption costs for commercial and industrial customers does not support the conclusion that interruption costs for these customers increased over the period. The paper concludes with a discussion of the implications of these findings for utility planning and regulation