Communities still in the dark after destructive storms

Of those still without electricity by 4pm on Wednesday, more than 100,000 are in the eastern part of the state.

Five regional hospitals are running on generator power, down from 15, as authorities rush to prioritise fuel and power restoration to these sites, but they could remain disconnected for at least three days.

There were widespread issues with the triple-zero emergency line, particularly in Gippsland, after 39 Ambulance Victoria branches lost power.

Premier Jacinta Allan said the storms inflicted significant damage statewide, with wind and trees taking down power lines and collapsing transmission towers near Geelong.

The damage could take weeks to fully fix.

At its peak about 530,000 properties were left without power due to the damage from storms, strong winds and lightning.

Generators could be sent out to communities expected to remain off the grid beyond 48 hours.

Emergency Management Commissioner Rick Nugent said the township of Mirboo North became isolated in the storms through road closures, with the Country Fire Authority stepping in to supply water.

The community has since been reconnected.

A dairy farmer was killed after being struck by debris while herding cows on a quad bike in nearby Darlimurla in South Gippsland on Tuesday evening.

He died at the scene.

WorkSafe is investigating the 50-year-old's death and police will prepare a report for the coroner.

Storm damage is to blame for the outages and not the fallen transmission lines, Australian Energy Market Operator (AEMO) chief executive Daniel Westerman said.

But the towers' collapses caused the shutdown of the Loy Yang A coal-fired power station, in the Latrobe Valley in Gippsland, and several wind farms.

"It sent shock waves through the transmission system," he told reporters.

The collapse tripped about 2800 megawatts of generation offline, along with about 1000MW of appliances and lights, forcing AEMO to instruct operator AusNet to reduce its load.

In doing so, roughly 90,000 customers were kicked off the network in the first 30 minutes.

Loy Yang A generates about 30 per cent of Victoria's power.

The station's owner, AGL, said two units had returned to service as of Wednesday morning with the remaining units expected to progressively come back online within 24 hours.

The network disruption pushed the spot power price in Victoria and Tasmania to its ceiling of $16,600 per megawatt hour, hundreds of times higher than typical levels.

Power outages and access issues caused 80 schools and childcare centres to shutter on Wednesday.

The prospects of students returning to class at these schools on Thursday remain unclear as authorities may not know conditions until the morning.

The widespread outages sent the train network into disarray and cut power to traffic lights.

Almost 500 phone towers remain down as of 4pm Wednesday.

The storms also knocked out 450 NBN sites, leaving a quarter of a million customers without internet access as service crews rushed to bring in backup generators.

The security of Australia's energy network is increasingly coming under threat from more destructive and frequent severe weather events fuelled by climate change, the premier said.

Australian Associated Press