Vector is being taken to court by the Commerce Commission for failing to meet minimum standards of electricity supply.
This is the second time in four years that the Commerce Commission has commenced proceedings against Vector which supplies more than 500,000 homes and businesses in and around Auckland.
Vector is the country's largest distributor of electricity and gas.
A Commerce Commission spokesperson said Vector was failing to meet minimum requirements for reliable supply and it had failed for four consecutive years.
The commission which had filed civil proceedings in the High Court at Auckland was seeking financial penalties for failing to meet quality standards.
It said the standards required Vector to stay within annual reliability guides for two out of three years.
In 2018, the commission also took Vector to court over what it said were an "excessive level of power outages" in 2015 and 2016.
In a statement, the Commission said Vector was co-operating with the commission investigation and would not challenge the proceedings.
More to come...
RNZ
