The Electricity Authority has signalled it will quickly investigate Transpowers role in contributing to Mondays power cuts before moving on to consider any broader issues raised by the outage.
It is now known about 34,350 homes had their electricity cut off without warning on Monday evening, when a cold snap that was forecast to leave supplies tight coincided with an unplanned outage of Genesis Tokaanu hydro power station on the Tongariro River.
Electricity Authority chief executive James Stevenson-Wallace said the review one of four requested or under way would focus on Transpowers processes and communications and should be completed by the end of the month.
Transpower botched calculations of how much power lines companies needed to drop on Monday to prevent a wider emergency.
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Hamilton-based Wel Networks said the error resulted in it having to cut power to 17,752 homes, when it only needed to cut power to 1373.
Transpower chief executive Alison Andrew said it acknowledged that the allocations it made to shed demand were in error.
Some networks were asked to shed more than their fair share, including Wel Networks. We sincerely regret the inconvenience and frustration this caused consumers on a cold night, she said.
While some networks took a larger share of the allocation overall, which we thank them for, importantly the action taken helped stabilise the system therefore avoiding a major failure.
Warning notices issued by Transpower also did not specifically request power generators increase their energy offers into the market until 1.02pm on Monday.
The Electricity Authoritys review will include looking at whether all generators that could have been on were running, and the quality of communications within the sector and with consumers.
Genesis Energy chief executive Marc England has said that by then it was too late for Genesis to turn on the third coal-fired turbine at its Huntly power station so it could make a meaningful difference, and that the crisis could have been averted had Transpower issued a full emergency notice earlier in the day.
The Electricity Authority said the second phase of its review would look at wider issues which were likely to include whether all generators that could run were running, and the adequacy of communications between all parties and with consumers.
The regulator said the results of its review would feed into another ordered by Energy Ministry Megan Woods from the Ministry of Business, Innovation and Employment.
Independent retailer Electric Kiwi has also filed a complaint that Genesis Energy and Contact caused an undesirable trading situation and abused market power by withholding generation from the market a claim both generators strenuously deny.
That complaint will need to be looked at separately by the Electricity Authority.
Transpower has also ordered its own investigation.
