California narrowly avoided implementing rotating outages on Monday while officials warned that the state’s power grid will face a bigger test on Tuesday amid a record-breaking heat wave. The state’s grid operator canceled its grid emergency late Monday evening after deploying supplies that helped keep the lights on even as electricity use soared to its highest level in five years. Power demand is forecast to be even higher on Tuesday, potentially reaching an all-time high as business and schools reopen after the long Labor Day holiday weekend amid triple-digit temperatures. “We are moving into the extreme part of this heat wave,” said Elliot Mainzer, chief executive officer of the California Independent System Operator, known as Caiso, which runs the state’s grid. Caiso expects supply shortfalls as high as 3,400 megawatts on Tuesday evening, the equivalent of several large power plants. […]