City of Windsor employees who work in the 400 building at City Hall Square will be asked to go back to work Friday.
Crews had been working to restore hydro service since the outage began Tuesday morning.
On Thursday evening, the City reported that power to the building had been restored and all systems were up and running as normal.
The 350 building, the main Windsor City Hall, was open as usual on Thursday..
The outage was initially blamed on a transformer fire, but further investigation revealed the failure of an underground cable.
Surveillance camera footage, posted Wednesday afternoon by Mayor Drew Dilkens, appears to show when the problem began.
Service Ontario, Service Canada, and the Provincial Offences Courts will reopen on Friday.
