Outback towns in western NSW spent Tuesday clearing fridges of spoiled food and medicines after mains supply around Broken Hill failed on Monday.
Generators kicked in at major hospitals but some primary schools were without power.
The area, which topped 33C on Tuesday, has experienced patchy electricity supply since severe thunderstorms last Thursday mangled transmission infrastructure connecting the region to the national grid
Gas-fired generators should have backed up the mains supply but one has been offline for almost a year and the second tripped about 5pm on Monday as the mercury reached 30C.
Extreme heat inside the second unit prevented crews inspecting it until about midday on Tuesday.
Power was due to return in the evening.
Premier Chris Minns criticised network operator Transgrid for not having redundancies in place "for precisely this scenario".
"There are rules that govern this, they should be followed and we'll find out why they weren't," he told reporters.
He also sought to dispel any notion government leaders in Sydney were not focused on the outage and fixing it.
The local council expects the cost of the disaster will be measured in the many millions of dollars.
Government disaster relief has been made available.
Local MP Roy Butler, who was briefed on the matter alongside government and industry leaders on Tuesday, said he had received conflicting information about the reason one generator had been offline since November.
But his immediate priority was the communities' needs, including access to food, during "an incredibly difficult time".
"We've had supermarkets unable to open, a lot of small businesses haven't been able to have staff come on shift," he told reporters.
"There's been a fairly rapid response to make sure (extra) generators are out there."
If there was an upside, it was the kindness of communities coming to the fore such as pubs offering up extra freezer space to residents, he said.
Not every one sang from the same song sheet, however.
A pharmacist arrived on Tuesday morning to find their business's briefcase-sized generator had been stolen, cutting power to medicine fridges.
"To the oxygen thief ... you've just ruined tens of thousands of dollars worth of essential medication and might mean some people may need to go without critical meds today," Outback Pharmacies said on social media.
Police were investigating the theft of the two-kilowatt generator.
Emergency work to reconnect the damaged transmission network is expected to take until at least November 6.
Residents have been urged to minimise electricity usage between 5.30pm to 10.30pm while generators are in place.
Nationals leader Dugald Saunders said the government had ignored locals' warnings about the impact of having a gas-fired generator offline for months.
Transgrid said additional generators would be installed overnight and further units were on the way.
"We expect power to be restored to all homes and businesses by tomorrow afternoon," a spokesman said.
A 24-hour rotating shift would begin Wednesday to rebuild the damaged powerline, he said.
Travellers have been urged to avoid the area surrounding Broken Hill, Tibooburra, Wilcannia, Menindee and White Cliffs unless absolutely necessary.
24°C