Taradale senior station officer Jamie Nichol said the building suffered minor damage and a scorch mark under the ridgeline of the roof. "It will be very easily repaired," he said.
Two fire trucks from Napier and one from Taradale attended the scene.
Unison customer relations manager, Danny Gough, said that the incident caused an outage for about 200 customers in the area for about half an hour.
In a separate incident in December 2013, a Britton Housemovers truck clipped a powerline in Central Hawke's Bay, sending the line into a roadside ditch. Several sheep stepped on the powerline and were electrocuted, while two dogs were also killed when they touched the dead sheep.
Britton Housemovers and director Arthur Ernest Britton were sentenced to four months' home detention and a $60,000 fine.
Then, in September this year, a King House Removals employee was forced to stay in his truck after the house he was moving caught fire when it snagged on powerlines near Kaiapoi, north of Christchurch.
Four fire crews attended and the blaze took about an hour to get under control.