Heavy rain and slips wiped out power to 6000 customers in Whanganui last night.
Slips brought trees down across a high voltage line supplying properties as an alternative to a substation that was flooded.
Powerco Acting Network Operations Manager Dean Stevenson said the land was unstable and roads were difficult to access.
“We are assessing the situation and will be doing everything we can to restore supply as soon as possible.”
Around 1000 customers across Rangitikei and Taranaki are also without power as slips and flooding make it impossible for field crews to get to affected areas.
Powerco urges people to stay well clear of any fallen power lines and phone Powerco’s emergency number 0800 272 727.
People can contact their energy retailer for information about power cuts or go to Powerco’s fault page