The IWK Health Centre was forced to cancel elective surgeries and non-urgent appointments after a power loss and generator failure on Wednesday.
The children's hospital in Halifax, which lost power shortly before noon, said it will be providing urgent and emergent services only for the rest of Wednesday.
"We are having difficulty with a generator on the children's site. However, our women's site and our Link building are regular power now so they're off the generator and back on main power," said Nick Cox, a spokesman for the IWK Health Centre.
"We're still having trouble getting power back up in the children's building."
While regular power was restored at 1 p.m., the hospital said it was still "an unstable power environment with ongoing internal power system issues."
At 4 p.m. there was another update from the hospital. While the power was restored, it came with a warning. "As a result of weather conditions in the Halifax area and an unstable internal power system, the status could change at any time."
Visitor restrictions will be lifted Wednesday night but there could be a restriction on elevator use.
The hospital said patients and families requiring further information about their elective surgeries or non-urgent appointments should call the number provided on appointment letters.
All ambulatory appointments will resume Thursday and most surgeries and procedures will proceed as scheduled.
In July, the IWK Health Centre cancelled surgeries over two days after a generator failed following a power outage. A backup generator was sent to the hospital under a police escort.
Cox said staff were working to fix the problem.
"Maintenance staff are working to investigate the causes and to get our systems back online," he told CBC News.
"I believe they are bringing in folks from the manufacturers as well, but I can't confirm that."
The IWK Health Centre services women, children, youth and families in the Maritimes.