The power station on Taveuni was due to be shut down at midnight to prevent any deaths through electrocution.
The island was expected to feel the brunt of Tropical Cyclone Mick, but the storm has altered course slightly and is heading more towards Viti Levu, rather than between the main island and Vanua Levu.
The Fiji Times says wardens at the island prison have secured the facility and mounted extra patrols.
The island hospital will resort to its emergency generator until the cyclone has passed and normal power resumes.
Hospital staff said shutters had been put in place, patients were secure in their wards and sufficient doctors and nurses were on duty.