Japan faces electricity shortages as a sustained heat wave pushes demand to record levels, straining a supply grid compromised by the forced shutdown of the world’s largest nuclear plant.

Tokyo Electric Power (Tepco), the world’s biggest private utility, on Wednesday asked about two dozen industrial customers to cut electricity use after temperatures in the capital reached 36 degrees, causing residents to crank up their air conditioners and pushing Tepco close to its 63.7m kilowatt capacity.