Transpower is undertaking further investigations into Monday's power outage across the central North Island.
More than 4000 properties in Raetihi, Taihape, Ohakune, National Park and Ongarue lost power due to a fault around 9am.
Transpower spokesman Geoff Wishart said there was a tripping (fault) on a 110,000 volt line feeding areas between Ongarue in the north and Taihape in the south.
"Normally, these areas are fed from the south, but because we had this line out for maintenance, they were being fed from the north."
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The northern part of the line tripped around 9am.
"When this sort of event happens, we have to get our crews to site to inspect the tripped line to ensure there is no continuing fault that would stop us restoring supply. For example, an actual break in the conductor or some physical obstruction.
"In this case, we inspected the line and once we established there was no physical problem with the line, we restored the circuit, and that happened around 11.10am."
He said it could have taken up to an hour to restore power to customers through the two affected companies, Powerco and The Lines Company, with homes reconnected by midday.
Wishart said they were unable to identify a cause initially and were further investigating the incident.