The inpatient unit of Victoria Infirmary Northwich (VIN), Cheshire, UK, has closed following an electrical test failure.
The 103-year-old wards, Binney and Verdin, will require complete rewiring to make them safe, involving a cost of £3m ($4.3m).
The wiring in the VIN wards was last replaced in the 1960s.
The inpatient unit and its staff have been temporarily moved to ward 19 at Leighton Hospital.
The inpatient unit was saved from closure in 2006 after a campaign by Save Our Northwich Inpatients Campaign (SONIC).