Residential customers of PG&E and other big utilities in California are headed for huge changes in their electricity rates under a plan disclosed late Wednesday by two state law judges, but the plan was immediately blasted by a consumer and environmental group. The state Public Utilities Commission is scheduled to vote on Friday on a far-reaching revamp of electricity bills that could boost power rates by as much as $10 a month for 80 percent of California's residential consumers, including those served by San Francisco-based PG&E.