California energy regulators approved measures yesterday aimed at promoting electricity conservation during a summer that is expected to stretch the state's grid to near breaking point. The California Public Utility Commission (PUC) ordered the state's utilities to put into place Gov. Gray Davis' "20/20 rebate program," a program that would reward customers with a 20 percent rebate on their monthly bills from June through September if they manage to cut their energy consumption by 20 percent.