NSW Premier Chris Minns has urged people to turn off their dishwashers and pool pumps amid blackout threats during Wednesday’s afternoon peak, and so consumers avoid “through-the-roof” energy costs on November’s hottest day since 2020.

It comes as parts of NSW bake in 30-plus-degree temperatures and concerns that reserve energy supply would likely be “tight”, given a surge in consumption and outages at four units across the state’s coal-fired power stations.

Urging residents to delay using dishwashers, washing machines, and pool pumps between 3pm and 8pm, Mr. Minns said that those who did jack up their air conditioning units may also face “through-the-roof” prices as the government attempted to stave off possible blackouts.

“We’ve been notified by the Australian Energy Market Operator that there are insufficient reserves in terms of generation across the day, and we are pursuing proactive measures to reduce the energy we’re using over the next 12 hours,” Mr. Minns said outside state parliament.

The AEMO used some of its own emergency powers on Wednesday to ensure sufficient electricity supplies in NSW, including a notice to the industry to ensure stable supply and starting negotiations with companies to reduce demand—a scheme known as the Reliability and Emergency Reserve Trader.

The use of the rarely used scheme underscores the vulnerability of NSW’s energy grid, caused by increased demand from households as some of the state’s largest coal power stations experience a spate of maintenance issues. The five-hour “low-usage window” the government hopes residents will adhere to, if safe to do so, also includes closing blinds, windows, and doors, with the temperature set to hit 34 degrees in the east of the city and 39 degrees in the west.

“Solar production in the energy market starts to come off at 3pm, exactly when people start to return home,” Mr. Minns said.

“So if you could not use your pool filter, dishwasher, or washing machine between 3pm and 8pm, you’d be helping the grid.”

Adding that those who did decide to put on a wash during that five-hour window to expect prices to go “through the roof," the premier said the announcement was “as much a consumer warning” as just about helping the grid.

“If you use electricity this afternoon, you’re going to get killed in terms of how much you pay, the amount of money (to run appliances) this afternoon will be through the roof,” he said.

Energy Minister Penny Sharpe said the government had activated its energy action response and voluntary demand reduction protocol.

The former urges government agencies to reduce electricity between 3pm and 8pm; the latter asks four state-based water agencies and the City of Sydney council to also reduce usage. Ms. Sharpe said power supply was expected to be “tight” this evening, which had been exacerbated by four offline units across the state’s coal-fired power stations.

“There is a buffer of energy supply in place of unforeseen events... But the concern today is that we don’t have that buffer,” she said, emphasising residents should take energy-saving measures if “safe to do so.”.

“But we’re trying to reduce demand across the system, and a lot of small (energy-saving) activities really help demand across the network.”

Two of four units at Bayswater coal-fired power station are offline—one planned and the other unplanned—while one of Eraring’s four is also down and one of Vales Point’s two.

“One of the reasons this (supply concerns, consumption warnings) is happening earlier is that a lot of maintenance (of station units) is going on, and we’ve had an earlier heatwave than usual, and it’s put pressure on the system,” Ms. Sharpe said.

“It’s very rare that we would have five days of heatwave in November, and that’s what’s caused the crunch here.”

Asked if the warnings and plea to residents “acknowledged” that without coal the network would be "stuck," Mr. Minns said the state’s energy mix was in "transition," noting the government’s previous decision to extend Eraring in the short term was to help situations like these.

During the height of summer, with fewer planned outages of units at places like Eraring and Bayswater, the government does not anticipate Wednesday’s warning to be commonplace, although conceding the situation was "dynamic.”