On October 5, 2016 at 3:10 PM a widespread power outage affected the Coolhousing Data Center. The failure happened during the planned maintenance work in the final stage of new power backup generator installation. However we were well prepared for the operation, co-operating closely with the electric generator supplier technicians, when the backup power circuit was tested, certified backup battery of central UPS had unexpectedly discharged, although the UPS electronics still showed about 50% of battery capacity left.