About 20,000 people in Broken Hill and surrounds were without power on Tuesday afternoon as the mercury headed for a forecast 35C.
It followed severe thunderstorms last Thursday that mangled transmission infrastructure connecting the region to the national grid.
A large-scale back-up generator trucked in, was supplying power to the region until it tripped at 5pm on Monday, leaving homes in the dark again.
Crews worked overnight to investigate the fault and expect to restore power throughout the Far West region on Tuesday evening, the NSW government said.
More generators are also on their way to provide additional back-up supply, while emergency work continues to rebuild the transmission network damaged in severe storms, it said.
Nationals leader Dugald Saunders said critical infrastructure was offline due to the outage. (Bianca De Marchi/AAP PHOTOS)
The pitch-black night got worse for a local pharmacist who arrived on Tuesday morning to find their business's generator had been stolen.
Addressing the "oxygen thief" behind the theft, Outback Pharmacies said the generator had been keeping medicine fridges running.
"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," it said on social media.
Critical infrastructure including the main hospital were also taken offline in Monday's outage, Nationals leader Dugald Saunders said.
A storm and suspected tornadoes on Thursday brought down seven transmission lines, causing rolling blackouts and brownouts.Â
Transmission network operator Transgrid is constructing temporary towers but that could take weeks.
Residents have been urged to minimise electricity usage during the evening peak: 5.30pm to 10.30pm.
Travellers have been urged to avoid the area surrounding Broken Hill, Tibooburra, Wilcannia, Menindee and White Cliffs unless absolutely necessary.
32°C