Vietnam is turning off street lights and manufacturers are switching operations to off-peak hours to keep the national power system running amid record temperatures in some areas that have caused a surge in demand.
As weather officials warn the heatwave could run into June, several cities have cut back on public lighting and government offices have been urged to cut power use by a tenth after state utility EVN said the national grid faced strain in coming weeks.
Temperatures this week are expected to hover between 26 and 38 degrees Celsius (78.8 and 100.4 degrees F), weather officials say.
To tackle the problem, Hanoi has shortened the duration of public lighting by an hour each day, while halving illumination on some major roads and in public parks.
"If people all save energy, all will have enough electricity to use, but if not, there will be a partial electrical overload that will put the power grid at risk," said Luong Minh Quan, an electrician with EVN in Hanoi.
Last week, Vietnam called for electrical devices to be turned off when not in use, and for air-conditioning to be kept above 26 degrees C (78.8 degrees F).
Authorities are pushing industrial consumers to operate during off-peak hours, when overall electricity demand is lower, to ease pressure on the national grid, said one industry source, who spoke on condition of anonymity.
More than 11,000 companies, from large factories of China's Texhong Textile Group to South Korean shoemaker Changshin, have agreed to cut consumption where possible, the Electricity Regulatory Authority of Vietnam (ERAV) says.
Some Hanoi residents turned to a waterpark to cool off, though experts say activity in extreme heat can cause dehydration and exhaustion.
"The water can help overcome the heat, as there are no other immediate solutions," said Tran Minh Trung, 48.