Energy Incident Register
Register / Grid infrastructure / EIR-0951
← Back to the list
Grid infrastructureUnited StatesEIR-0951

Squirrel-caused equipment failures knock out power at Colorado substation twice in two days

2026Published 17 Sept 2026Responsible editor: Chief Editor

MinorElectrical
Estimated damageEstimated by the register's adjusterHow? Know the real figure?
Figure hidden: shown to subscribersMedium confidence
supply cut for about •• daysShown in the record →Full estimate
From the recordRoot cause hiddenFailed part hidden
Where
substation near Ridge Road in Castle Rock, Colorado
Operator
CORE Electric Cooperative
What
two squirrel-caused outages on consecutive days
Cause
squirrels causing equipment damage and short circuits
Outcome
quick repair restored service to 4000 and 1300 customers

Companies named in the reporting of this entry (being named is not a finding of fault): CORE Electric Cooperative

What happened

A substation operated by CORE Electric Cooperative near Ridge Road in Castle Rock, Colorado, experienced two separate wildlife-related outages on consecutive days. On the first day, a squirrel caused an explosion at the substation that knocked out power to more than 4,000 customers. The following day, another squirrel damaged distribution equipment at the same substation, causing a further 40-minute outage affecting about 1,300 customers. In both cases, utility personnel quickly identified and repaired the faults to restore service.

The cooperative stated that wildlife, mainly birds and rodents, causes an estimated 5 to 10 percent of outages on its system each year. The utility said its system is designed to allow switching of load to other areas to speed restoration while repairs are made.

Contributing factors

Wildlife intrusion by squirrels causing equipment damage and short circuits at an exposed substation location; the cooperative noted it cannot fully enclose every piece of substation equipment.

Lessons learned

  1. Squirrels at an exposed substation can cause repeated short circuits in quick succession, so operators should check all accessible bushings and insulators after the first event.
  2. Distribution networks with load-switching allow faster restoration during faults, so insurers should verify this feature at similar substations.
  3. Wildlife causes 5 to 10 percent of outages each year, so utilities must balance full enclosure with targeted hardening at high-risk sites.

More lessons on electrical protection and isolation, from every incident on the register.

Not yet known

  • Age and model of the damaged equipment
  • Total cost of the repairs
  • Exact type of equipment short-circuited

This entry is updated when these are reported. Get an alert for the next one like it.

Source

msn.com

Published 2026-09-17. Written from public reporting. Descriptive, not investigative. See the data accuracy disclaimer.

See the register's stories first in Google: add it as a preferred source.

Chart to reuse with this story: Grid infrastructure incidents in the United States, by year, free with a credit (PNG).

Grid infrastructure incidents in the United States: 415 entries, with a free alert for the next one.

Substation and transformer fires: the counts, the latest entries and a free alert for the next one.

Browse the full register or submit an incident.