Series of errors behind Top End blackout

A series of human errors, outdated systems and an inadequate regulatory regime were behind a huge blackout in the Northern Territory that cut off power from Darwin to Katherine.

Some 140,000 people were affected by the power outage on March 21 when a circuit breaker failed and an "unnecessary" switching procedure to isolate it tripped transmission lines, disconnecting generating units across the Top End, according to a Utilities Commission report.

It shows that Power and Water Corporation (PWC) needs to undergo a major cultural change to break away from slack unionised work practices, Treasurer Dave Tollner said on Tuesday.

The procedure for re-booting the Darwin-Katherine power system, which spans more than 300km, had not been reviewed since May 2010, shortly after the last major blackout.

The report found that human error combined with the failure of back-start generators raised concerns "there may be a lack of adequate procedures, training and understanding of the potential impacts on power system security".

It said there was no apparent risk assessment or check to deal with the malfunctioning circuit breaker.

Mr Tollner said that had the 2010 recommendations been acted on, the blackout could have been avoided.

He slammed the Electrical Trades Union for "bullying" voters at Saturday's Blain by-election, and said he was considering referring its NT branch to the royal commission on union governance and corruption.

"I am very concerned about the union involvement in the PWC ... it seems to have been used as their plaything," he said.

But he stopped short of accusing the union of corruption.

"What this report indicates is this entrenched culture of cronyism and slack work practices of the corporation," Mr Tollner said.

The government should admit its cuts to PWC's repairs and maintenance budget contributed to poor power reliability, the opposition's essential services spokeswoman Nicole Manison said.

Mr Tollner said the NT's energy market would be far better governed by the Australian Energy Regulator, and said the report makes the case for the structural separation of power and water, the legislation of which will be debated next month.

The government denies the separation is preparation for privatising the two entities.

Mr Tollner said he would demand that PWC give monthly updates on how the Utilities Commission's recommendations will be implemented.