Transformer failure causes large power outage in Denver metro area
Feb 2026Published 7 Sept 2026Responsible editor: Chief Editor
- Where
- Xcel Energy substation, southeast Denver metro area
- Operator
- Xcel Energy
- What
- Transformer failure caused outage for over 195,000 people
- Cause
- Transformer failure and resulting equipment damage
- Outcome
- Power restored to all by 5:47 p.m., transformer replaced
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Companies named in the reporting of this entry (being named is not a finding of fault): Xcel Energy
What happened
A transformer failure and resulting equipment damage at an Xcel Energy substation just before 3 p.m. on Sunday caused a power outage that left more than 195,000 people without electricity in the southeast Denver metro area. The outage affected Aurora 911 service, RTD light rail, and operations at Denver International Airport, including concourse trains. CORE Electric customers were also impacted. Xcel said power was restored to all customers by 5:47 p.m. the same day and that the transformer was being replaced.
Aurora later said 911 service was working again, and the airport reported that operations had returned to normal. RTD ran shuttle buses in place of the H Line and the R Line.
Contributing factors
Xcel Energy said a transformer failure and the resulting equipment damage at one of its substations caused the outage. No further cause is reported.
Lessons learned
- A substation transformer failure can cut power to many customers and disrupt 911, rail and airport services, so operators must map dependent loads in advance.
- Restoration after a substation transformer failure requires a plan to replace the unit and verify when linked services recover.
- When a substation supplies emergency and transport loads, outage plans must include direct coordination with those services.
More lessons on outages, backup supply and restoration, maintenance, inspection and ageing assets, from every incident on the register.
Not yet known
- Further cause of the transformer failure
- Transformer model and age
- Cost of damage and replacement
This entry is updated when these are reported. Get an alert for the next one like it.
Source
Other entries that name Denver
Published 2026-09-07. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.
