Mystery surrounds a huge surge in the price of electricity this morning.
The price spike, which only affected the North Island, left Flick Electric with an interim bill of $3999 per megawatt hour just after 8am today.
The company said it would normally pay about $75 a megawatt hour.
But the $3999 figure was dwarfed by the massive price of $192,260.25 per megawatt hour recorded on a pricing publication issued by the Electricity Market.
That figure refers to bids for electricity that are made every five minutes and later averaged out.
Electricity sources told RNZ the five-minute figure might have been a default position adopted by a computer, and a sum of money that size would not have been paid by anyone.
The default position could have been adopted in the wake of a technical fault near the Haywards substation near Wellington this morning.
That fault disrupted technology that converts direct current into alternating current.
But Transpower said other conditions might also have contributed to the problem.
Transpower is responsible for the practicalities of the electricity system as well as running the national grid.
In a statement, it said electricity demand was very high this morning while small quantities of power were being offered into the market.
Wind farms were also only producing minimal amounts of power.
At the same time, a lot of electricity was being sent from the South Island to the North.
This latest incident comes seven weeks after similar problems that led to allegations against Meridian Energy.
Meridian was cleared of an immediate charge levelled against it but is still being investigated by the Electricity Authority.