A San Diego consumer watchdog group filed a motion Tuesday urging the California Public Utilities Commission to compel San Diego Gas & Electric Co. to upgrade a key substation in the East County so more electricity can move through it.

Utility Consumers' Action Network stated in the two-page filing that the upgrade would offer the potential to save electric ratepayers in San Diego County and around the state $12 million a year. The substation is the point where power transported across a transmission line that runs near Interstate 8 reaches the utility's distribution system for customers in San Diego County and southern Orange County.

According to the filing, part of the time the Bonita substation handles 1,900 megawatts of electricity part of the time and 1,450 megawatts at other times. A megawatt, the standard measuring unit for electricity, is what it takes to keep the lights on in 1,000 homes.

The filing urges that steps be taken to boost the capacity to 1,900 megawatts at all times.

The filing suggests San Diego Gas & Electric, on its own, would be reluctant to boost capacity because that could weaken its argument for the need for the proposed Sunrise Powerlink power line well to the north, through the backcountry of North County.

Scott Crider, public affairs manager for the Sunrise project, said San Diego Gas & Electric will address the issue in a rebuttal to be filed with the commission on June 15.