The IWK hospital has postponed surgeries for the second day in a row, as a result of yesterday's power loss.
Only two operations were put off Thursday.
Nova Scotia Power crews are still on the scene.
A Nova Scotia Power substation failed after 10:30 a.m. on Wednesday, which postponed all elective surgeries and non-urgent cases for the day.
Wednesday's outage lasted almost six hours.
At the time, the neonatal unit was at "code census", which means it was full, with 48 newborns, including 15 who were on life support systems.
"It was a very serious potential issue," said Joe Hyndman, vice president of medicine at the hospital.
"We were dependent on generator and of course generators break down."
Hyndman said the hospital had problems with one generator in the children's department, but they were able to keep it running by "jerry-rigging" a cooling system.
"We were afraid it would shut down," he said.
There were operations going on in the hospital at the time of the outage, but they didn't experience any power loss because a back up battery kicked in, said Hyndman.
A backup generator was trucked to the IWK Health Sciences Centre Wednesday. It arrived just as the power came back on, and remains on the site.
The generator came from Burnside as a precaution and was escorted by police.
Nova Scotia Power crews traced the problem to a substation connected to the IWK and the Victoria General Hospital.
The Victoria General Hospital also reported a brief outage Wednesday morning.