The Electricity Authority says it's made urgent changes today, to make sure consumers aren't disadvantaged by big deals.

The amendment to the Electricity Industry Participation Code means that deals for more than 150 megawatts, can only go ahead if they meet specific criteria.

It impacts powercos' ability to strike a deal with Tiwai Point aluminium smelter, as it works on plans to stay operating beyond 2024.

LISTEN ABOVE