Energy providers blamed unforeseen airconditioner use and fuse faults for the blackouts. The outages fanned a political dispute about power supply during extreme temperatures, with the state opposition blaming the closure of Hazelwood power station. The Andrews government rubbished suggestions the Hazelwood closure was behind the failures. Energy providers blamed unforeseen airconditioner use and fuse faults for the blackouts. Credit:Glenn Hunt "Despite some loose and thoroughly inaccurate commentary this morning, the Energy Market Operator has confirmed there was sufficient energy, more than sufficient energy, to power the entirety of our state, so this was not a power supply issue."

Energy Minister Lily D'Ambrosio also dismissed claims there was an energy shortage, and lashed out at private energy providers for crippling the state's power distribution network. "Nobody should have to cop these situations," she told radio station 3AW. "People are entitled to have confidence in their energy system. Our poles and wires and substations let us down." The providers’ failure to handle increased demand loads has raised questions over where the heavy investment in distribution networks has actually gone. There are concerns of a gold-plated, ineffective system that has contributed to rising power bills. Distribution networks – the poles and wires – account for nearly half of all energy bills on the east coast, and the Australian Competition and Consumer Commission has previously accused network operators of over-investing at consumers' expense. Victorian Energy and Environment Minister Lily D'Ambrosio. Credit:Hayley Mills/Latrobe Valley Express

Loading Ms D’Ambrosio said she had requested an explanation from private energy distribution companies as to what went wrong. "They must consider requests urgently and I’ll be monitoring closely how these private companies respond,” she said. The Australian Energy Market Operator said there was more than enough capacity in the state’s energy grid on Sunday, with no lack of reserve, even though Victorians set a record for peak power demand. It confirmed energy distributors were responsible for forecasting need and ensuring the network could cope.

Sunday's heatwave did not stretch the grid enough to warrant the energy watchdog's lowest warning level, which is given when threat to supply is possible but unlikely, even at the point when demand peaked at more than 9.2 gigawatts about 6pm, with the temperature still in the high 30s. Meanwhile, Powercor has announced it is conducting its own investigation into the outage to determine what steps need to be taken to strengthen the networks. "Multiple outages were also experienced across the CitiPower and Powercor networks on Sunday as a result of extreme weather conditions," a Powercor spokeswoman said. "There were 724 customers off power in the CitiPower network and 36,690 customers off power in the Powercor network."

She said customers may be eligible for compensation under the Guaranteed Service Level payment scheme or through a customer claims process. United Energy, Powercor and CitiPower spokeswoman Emma Tyner said they were "extremely sorry" for the outage. "The prolonged high temperatures and humidity through the weekend significantly increased electricity demand at many locations across the network, which resulted in multiple power outages," she said. "In most cases, substation fuse faults were the main cause of the outages.'' Provider AusNet said its outages peaked about 5.30pm, when about 9000 homes were without power.