According to an analysis by the Public Interest Advocacy Centre, combined, the networks have launched bids to recover an extra $5.72 billion over four years. While price cuts are already locked in for this financial year, if successful, the networks could seek to recover this extra revenue over the remaining three years of this current price determination. This would mean the networks' 3.4 million customers could end up paying $1682 in total, or $560 extra a year for three years starting next July. "These legal proceedings are very important because consumers face paying hundreds of dollars more on their electricity bills every year, a senior water and energy policy officer at the Public Interest Advocacy Centre, Oliver Derum, said. Because electricity networks are monopolies, the amount that they can charge is determined by regulation.

Under a determination made in April by the Australian Energy Regulator, NSW electricity bills would have shrunk by between $106 to $313 this financial year, depending on their provider. Network costs make up about half of what electricity retailers charge consumers. PIAC is also challenging the AER's decision to say it is too generous to the networks. The unprecedented legal case will test new laws for electricity regulation and is politically sensitive as the NSW government seeks the best price from potential bidders to privatise the networks. A spokeswoman for Networks NSW said it was necessary because the electricity networks had not been given enough time to adjust to lower revenues.

The networks had already stripped $3 billion from capital and operating programs and reduced headcount by 3500 jobs since 2012 in a bid to control costs. "Ausgrid, Endeavour Energy and Essential Energy are committed to doing all they can to place downward pressure on electricity prices," she said. Networks had proposed to make another 2200 job cuts by 2019, but the AER decision meant 2750 jobs were immediately unfunded, with no provision for redundancy payments. "The AER's significant cuts will lead to more jobs reductions over a shorter period of time." The revenue cuts would also have a "significant impact" on vegetation and bush fire risk mitigation programs across the state, she said.

Thursday's public hearings in Sydney will hear from a range of consumer groups on Thursday, including the Consumer Action Law Centre, Energy Consumers Australia, Uniting Care and One Big Switch. A spokesman for One Big Switch, Joel Gibson, said many taxpayers were unaware they were in effect paying for the legal challenge by the networks - which are state owned - to force them to pay higher bills. "It would be an awful irony if the networks were successful in using public money to fund their challenge to take those price cuts away from consumers who have seen their bills double over the past five to seven years." The chief executive officer of the Energy Consumers Association, Rosemary Sinclair, said households should not pay more for electricity. "We think the result of that is that consumers would not be paying efficient prices and that would be bad."

"These are monopolies and we need to be assured that their costs are efficient. The best way to do that is to use a benchmark. The AER has done that and it seems to be a reasonable benchmark. We don't want firms not to be making proper returns, but on the other hand, households ought not to be paying any more than necessary." The chief executive of the Consumer Action Law Centre, Gerard Brody, said the AER's price determination was already too generous to the networks. "The tribunal is obliged to only change the determination if it is in the long term interest of consumers." "We really don't know how the tribunal is going to apply it." "It does seem we're paying too much."