Power was out across the Wanganui region Wednesday morning after a failure on a 33,000 volt line.
Large areas of the region have been affected by the outages which began around 8.30am.
Powerco network operations manager Phil Marsh said supply to approximately 8600 customers was interrupted due to the outage at approximately 8.20am. He said supply to all but 200 affected consumers was restored by 9.55am.
"The fault occurred following an overhead line failure on a 33,000 volt line. The exact
cause of the failure is under investigation," Mr Marsh said.
A spokesperson for the national grid operator Transpower, Geoff Wishart, said this fault caused a transformer at its Brunswick substation to trip and cut service to about 12,000 consumers.