Equipment failure at a Carterton substation sparked a grass fire on Norfolk Rd on Sunday night.
Power was cut to about 290 homes as firefighters worked to control the blaze which spanned 150m by 20m.
Fire officer in charge Doug Flowerday said when fire crews arrived, they had to stand by, controlling the blaze from a careful distance until Powerco advised the power supply was cut.
It was then safe to spray water near the high voltage line.
“It’s just the sort of place you don’t want to be playing around until you know it’s safe,” Flowerday said.
At time of publication, Powerco was still investigating the cause and any damage at the substation.
Powerco network operations manager Karen Frew said power supply was lost at 6.30pm.
She hoped power would be restored later Sunday night.