Several thousand Sun Prairie utilities customers lost power early Tuesday morning, according to a release.
Officials said the Bird Street substation had an insulator failure around 5:45 a.m.
All customers had their service restored by a little after 6:30 a.m., according to the release.
Officials said the likely cause of the failure was a lightning strike during the stormy weather that passed through the area.
The damaged insulator shut down the Bird Street substation that is designed to protect all circuits and homes served by it, according to the release.
Officials said their initial response was to switch all of the affected circuits to be fed from other substations around the city.
Crews remain at the Bird Street substation making repairs to the damaged equipment, according to the release.