County annual report · FIPS 47187
2021 Williamson County, TN Power Outage Report
In 2021, customers in Williamson County, TN went without power for an average of 1.1 hours, a total of 136K customer-hours (Tennessee average 3.7 hours). That ranks 61st worst of 84 Tennessee counties and 2623rd of 2,974 nationally.
Compared with TN, the US and 2020
Coverage line is EAGLE-I's share of Tennessee customers tracked each year.
Biggest outages in Williamson County, 2021
The 10 outage episodes with the most customers out at once. Times are UTC.
| # | Started (UTC) | Ended (UTC) | Duration | Peak out | Customer-hours |
|---|---|---|---|---|---|
| 1 | January 26, 2021 00:45 | January 26, 2021 09:00 | 8h 15m | 5,388 | 2,931 |
| 2 | March 27, 2021 12:00 | March 28, 2021 22:45 | 1d 10h | 3,619 | 21K |
| 3 | May 3, 2021 06:15 | May 3, 2021 20:15 | 14h | 3,420 | 3,456 |
| 4 | May 25, 2021 17:45 | May 25, 2021 22:15 | 4h 30m | 3,418 | 5,132 |
| 5 | August 10, 2021 11:45 | August 10, 2021 22:30 | 10h 45m | 2,854 | 1,929 |
| 6 | January 1, 2021 18:30 | January 1, 2021 22:30 | 4h | 2,581 | 2,133 |
| 7 | August 21, 2021 10:45 | August 21, 2021 11:00 | 15m | 2,569 | 642 |
| 8 | January 21, 2021 07:00 | January 21, 2021 09:30 | 2h 30m | 2,362 | 5,339 |
| 9 | March 24, 2021 18:00 | March 24, 2021 22:45 | 4h 45m | 2,204 | 670 |
| 10 | February 22, 2021 09:00 | February 22, 2021 14:00 | 5h | 1,901 | 1,916 |
Outage episodes by size in 2021: 77 reached 100+ customers, 30 reached 1,000+ customers, 0 reached 10,000+ customers.
Utility reliability filed with the EIA
SAIDI (average outage time per customer) and SAIFI (average interruptions per customer) that utilities serving Williamson County reported on EIA Form 861 for 2021, or their most recent earlier filing. Utility-wide figures, not county-specific.
| Utility | EIA year | SAIDI | SAIFI | SAIDI excl. major events | SAIFI excl. major events |
|---|---|---|---|---|---|
| Duck River Elec Member Corp | 2021 | 7.7 hrs | 2.06 | 2.2 hrs | 1.59 |
| Middle Tennessee E M C | 2021 | 65 min | 1.00 | 55 min | 0.96 |
| City of Dickson | 2021 | 12.0 hrs | 6.34 | 5.6 hrs | 4.62 |
| Nashville Electric Service | 2021 | 12.8 hrs | 1.82 | 1.7 hrs | 1.27 |
| Columbia Power System - (TN) | 2021 | 1.6 hrs | 2.78 | 74 min | 2.48 |
About this data
- Outage figures come from DOE/ORNL EAGLE-I, which records customers out by county every 15 minutes. EAGLE-I tracked about 73% of Tennessee's customers in 2021; utilities it does not see are not counted.
- Hours per customer = outage customer-minutes ÷ 123,583 customers (ORNL modeled county customer count), including major storm days. It is comparable across counties but is not the SAIDI a utility files.
- An outage event is a continuous stretch with customers out; counts at 100, 1,000 and 10,000+ use its peak.
- Years loaded: 2015–2025. Williamson County has data for 2015–2025.
Cite this report
MassOutage (massoutage.com), Williamson County, TN annual power outage report, 2021, data as of Oct 3, 2026 02:41 UTC, sources: DOE EAGLE-I (https://eagle-i.doe.gov/); EAGLE-I modeled customer counts (MCC) (https://figshare.com/); EIA Form 861 (utility reliability) (https://www.eia.gov/electricity/data/eia861/). https://massoutage.com/reports/2021/tennessee/williamson-county