The NSW government appears to have scored a partial win in a bid to push up average household electricity prices by as much as $560 a year, in a court decision that could help the Baird government privatise electricity networks.

But the case is so complicated that it threatens to delay NSW premier Mike Baird's plans to sell long-term leases for 50.4 percent of two of its three remaining electricity network companies. It sold Transgrid for $10.3 billion last December.