National grid operator Transpower is investigating how a high voltage line snapped in South Auckland, falling on a row of houses.
The 220-kilovolt transmission line came down on houses off Whetstone Road, near Te Irirangi Drive, in Manukau on Friday.
Witnesses say there was a loud bang, smoke and crackling lights. Some people were trapped in their homes for a period of time.
The incident comes a week after 74,000 Auckland customers were cut off due to problems at the Penrose sub-station, reigniting calls for upgrades to the national grid.
The Fire Service says it is lucky no one was injured on Friday and at least one resident says they narrowly escaped being hurt.
Transpower general manager of system operations Kieran Devine says the line was live for a fraction of a second and someone could have been badly injured or killed.
Mr Devine says he is not aware of a similar incident ever happening before.
He says the line is one of six which bring power into Auckland, so there was no loss of electricity. The other five lines are enough to carry the load and he does not expect any outages.
Transpower says it will compensate residents for any damage.
