The group overseeing California's power grid is preparing for another heat wave across the state this week. The California Independent System Operator says they are not anticipating power shortages , but they have restricted maintenance for energy suppliers on Tuesday and Wednesday from Noon to 10:00 PM to make sure all transmission lines and generators are in service during the heat wave. Last month the ISO issued several emergency alert watches, the lowest of five levels on the scale that could lead to rolling blackouts, especially in the evening when renewable energy drops off the grid.