A consumer watchdog coalition wants Vector to pay $50 each to the 230,000 Auckland households affected by a big power cut last month.
It says Vector should then take legal action against national grid operator Transpower to recover the $11.5 million cost.
The Consumer Coalition on Energy says Vector, Auckland's
major power supplier, should stick to its "Vector Promise", which pledges a $50 credit to customers whose power is off for more than 2 1/2 hours.
Vector makes the promise on its website, but says it does not apply if the power loss is caused by storms or extreme events outside its control.
It says it is not obliged to pay, and is blaming Transpower for last month's blackout.
A Vector spokeswoman said the promise was voluntary, and applied only to faults on Vector's network and assets.
She said the June 12 power loss was on Transpower assets, so the Vector Promise did not apply.
"Transpower was unable to deliver power to our network," she said. "We cannot take responsibility for the failure of other companies' assets."
But the watchdog group - a coalition of the Consumers' Institute, Business New Zealand, Federated Farmers and the Major Electricity Users' Group - has written to Vector, urging it to honour the promise and try to recoup the costs by seeking damages from Transpower.
Major Electricity Users' Group executive director Ralph Matthes said the blackout would have cost many people more than $50.
He said Vector would have a strong damages claim against Transpower, after an independent report in July found the cut was avoidable, and was caused by the failure of two 40-year-old shackles holding wires at the Otahuhu B substation, maintained by Transpower.
Newmarket Business Association general manager Cameron Brewer said Vector should also pay out on a separate "promise" on its website to pay $200 to commercial customers who are without power for more than 2 1/2 hours.
Vector has about 39,000 commercial customers.
