What this data measures

Year-by-year reliability performance for individual electric distribution utilities, showing SAIDI and SAIFI trends over time. This allows detailed examination of how a specific utility's reliability has changed, including the effect of major weather events.

How this data is constructed

Reliability data are reported by utilities through the EIA Form EIA-861 Reliability Supplement. Individual utility records include both "excluding major event days" and "including major event days" measures.