Our Methodology

Data Sources

PlainUtility draws from two publicly available datasets — both directly linked so you can verify the upstream values:

Reliability Metrics Explained

PlainUtility tracks two standard IEEE reliability indices as reported to the EIA:

  • SAIDI (System Average Interruption Duration Index): The average total minutes per year that the average customer is without power. Calculated as total customer-minutes of interruption divided by total customers served.
  • SAIFI (System Average Interruption Frequency Index): The average number of times per year the average customer experiences a power interruption. Calculated as total customer interruptions divided by total customers served.

Both metrics are reported in two forms:

  • With major event days (MED): Includes all outages, including storm and catastrophic events. Reflects the full customer experience.
  • Without major event days (nMED): Excludes events classified as Major Event Days (typically large storms). Reflects day-to-day infrastructure reliability.

Processing Pipeline

We download EIA Form 861 Reliability data files from eia.gov and process them through our ETL pipeline:

  • Parse annual reliability files for 2020–2023, one file per year.
  • Normalize utility names and EIA utility IDs across years for trend analysis.
  • Treat dot placeholders (utilities that did not report a metric) as NULL — not zero — to avoid distorting averages.
  • Compute 4-year trends for SAIDI and SAIFI (with and without MED).
  • Merge ZIP-to-utility mappings from OpenEI URDB service territory files.
  • Compute state-level weighted averages from utility data.

ZIP Code to Utility Mapping

ZIP-to-utility mappings come from OpenEI's URDB service territory files, updated periodically as utilities update their service territories. Some ZIP codes may be served by multiple utilities. Service territory boundaries can change year over year.

Data Vintage

Current data covers 2020–2023. The EIA publishes updated Form 861 data annually, typically 12–18 months after the survey year. We update our database when new annual data becomes available.

Data Accuracy Commitment

All reliability metrics are presented exactly as reported by utilities to the EIA. We do not modify SAIDI or SAIFI values, adjust for Major Event Day classification differences, or apply our own normalization. Where a utility did not report a particular metric (indicated by a dot placeholder in EIA files), we treat it as missing data rather than zero to avoid distorting averages or state-level calculations. Trend calculations use only years where data was reported, ensuring that intermittent reporting does not create misleading trends.

Limitations

  • Not all utilities are required to report reliability data to the EIA — smaller utilities and some cooperatives may not be represented.
  • Major Event Day classification varies by utility, which can affect comparability of nMED figures between utilities.
  • ZIP-to-utility mappings may not precisely reflect actual service boundaries, especially in areas served by multiple utilities.
  • Reliability data reflects self-reported utility figures and is subject to the accuracy of each utility's internal outage tracking systems.
  • State-level weighted averages are influenced by the utilities that report data; states where fewer utilities report may have less representative averages.

Not Affiliated

PlainUtility is not affiliated with the U.S. Energy Information Administration, the Department of Energy, or any electric utility. We are an independent data portal presenting public government data.