Sergeant Nigel Ramsden of the road policing unit said an investigation would be held to determine whether it was a mechanical fault or excess speed which caused the crash.
Mr Ramsden said the wet weather may also have played a part, although the surface of the road was in good condition.
"The truck has come around the corner and slid into the power pole. There were no injuries and the power lines have remained intact."
Across the road, Eleanor Mason was sitting with grandchildren Cajun Kerr, 10, and Natalia McNally, 3, watching television when the power went out.
She said it was lucky they had just finished eating dinner, but hoped the power would be back on before too long otherwise the children would not want to go to sleep.
Cajun said he had been watching television when he heard a funny noise.
"It was like the kid of noise you hear when the TV goes funny with the fuzzy lines.
"We went outside and saw the truck had crashed."
The Powerco outages and faults register said the power outage affected homes in about 28 Matua streets.
The power was expected to be restored by about 9.30pm.