Queenslanders have been told to cut their energy use to make sure the network can cope after a fire took out a major plant and cut power to half a million customers.
The Australian Energy Market Operator has told people to avoid using heavy appliances on Tuesday night, after the blaze at central Queensland's Callide Power Station robbed the state of a major generator.
Consumers have been urged to "minimise stress on the system" until 9pm to ensure there's no shortfall - something that could cause brownouts or blackouts.
So far the system is coping with the help of imported electricity after Tuesday afternoon's fire at the coal-fired power station, which is now surrounded by a 550-metre exclusion zone.
Firefighters are yet to get inside the plant and don't know if the fire is out but reports from the scene, near the town of Biloela, suggest there is minimal if any smoke.
All plant workers have been evacuated and no one was hurt.
Danny Donald from power company Energex says he's not sure the Queensland network has experienced an outage of a similar scale.
But he said restoration was quick, and everyone who lost power was back online about two hours later.
Mr Donald warned there would be "instability" in the network in coming days and confirmed AMEO had issued a "lack of reserve" notice to the national market.
That means the national supply system may not have capacity to meet Queensland's needs in the short term.
"It's something that we will work on if we need to ... but we're not at that stage yet," Mr Donald has told the ABC.
Former Brisbane lord mayor Jim Soorley chairs the board of CS Energy, which operates the Callide plant. He says there's no information on the scale of the damage, and does not know when the four generating units will be back on line.
He's hopeful staff will get back inside on Wednesday after such "a serious reduction of capacity in Queensland" and suggested reports of an explosion were wrong.
Queensland Fire and Emergency Services deputy commissioner Mark Roche says fire crews with breathing apparatus are waiting for the plant to be made safe before going inside.
"The initial information to us was that there were explosions, or people have reported explosions," Mr Roche told the ABC.
"We need to get in there and determine if the fire is still active of if it's been extinguished by the internal crews. They would have isolated the incident, tried to shut off the air supply. If they were able to do that, it may be that the fire is out."
Earlier, Premier Annastacia Palaszczuk said emergency plans had been activated to shore up the state's power supply.
"There is a process in place to gradually and safely increase supply from other power stations. These scenarios are planned for and our recovery plan is in place," she tweeted.
The widespread blackouts affected consumers from the Queensland/NSW border to north Queensland and blacked out major intersections, causing hectic conditions on the roads.
Rail services were not affected but Gold Coast trams were hit.
The international terminal at Brisbane Airport was also affected, but only for 15 minutes. Generators kicked in to keep air traffic controllers on line. The domestic terminal wasn't impacted.