Transpower says it has made progress raising a temporary tower in Northland, but it has been unable to fully finish the operation.
A pylon fell near Glorit earlier this week, causing region-wide outages that impacted tens thousands of residents.
Transpower's general manager of grid delivery, Mark Ryall, said crews had worked throughout Saturday on the new tower, which would restore one of two 220kV circuits to the region.
However, they had been unable to complete the transfer of all the conductor wire to the tower before dark.
"It is complex and challenging work and we have encountered delays that mean we weren't able to complete the work before it got dark and the weather deteriorated," he said.
"To ensure the crews can complete the work safely the final works will be delayed until tomorrow morning."
A heavy rain watch was in place for Northland, north of Whangārei, from midnight Saturday to midday Sunday and downpours were expected throughout the night.
Ryall said crews were still on track to meet Transpower's Sunday deadline.
"We thank Northland communities for their continued patience. I know it makes a big difference to our crews putting in the hard work on the ground."
There was sufficient electricity supply to meet Northland's weekend demands through existing 110kV circuits while the 220kV circuit was restored, he said.
RNZ
