Two units at a major NSW power plant are not operational as soaring temperatures place pressure on the state's energy supply.
AGL Energy confirmed on Friday two of the four units at its Liddell Power Station had been shut down due to leaks in boiler tubes.
The unit shutdowns come as the Australian Energy Market Operator forecast the highest-ever energy demand in NSW - about 4700 megawatts.
"Currently AGL has all of its assets running except for two units of the Liddell Power Station, due to forced outages to repair boiler tube leaks, which can occur without warning," AGL said in a statement to AAP.
AGL expects one of the units to be up and running by late Saturday night but the second won't be back online until late next week.
The AEMO has warned of potential "load shedding" across the state on Friday evening in order to keep the NSW network stable.
Blackouts could occur across the state for one to two hours. They'd be rotated across the network to minimise the impact on residents.
The Liddell Power Station is part of the AGL Macquarie power network. The private energy company purchased it from the NSW government in 2014.
The AGL Macquarie network produces approximately 12 per cent of the power for eastern Australia.
Labor leader Luke Foley demanded an explanation from the Berejiklian government earlier on Friday.
"We've got the energy minister out there now on radio telling people to turn off their air conditioners, to turn up the temperature in their refrigerators, just to keep the lights on," Mr Foley told reporters.
"What he hasn't told us is that only two of the four units at the Liddell Power Station are operational."
Energy Minister Don Harwin said it was common for coal-fired power stations to have transient faults.
"This is the nature of a coal fired power stations," he told reporters in Sydney.
"(But) Lidell is playing its part and its owner is playing its part in ensuring that we get through today in good shape."