Top Energy said power has been fully restored to all areas of Northland that lost it yesterday.
30,000 properties - from Cape Reinga to just north of Whangarei - were without power for several hours because of a fault at Kaikohe where the Far North network joins the national grid.
By mid-afternoon yesterday, most customers had electricity again but some pockets took longer to fix.
The lines company Transpower said investigating what went wrong had been a tricky process.