Electrical customers across a five-state region will help shoulder the cost of burying new transmission lines through south Minneapolis, a state rate regulator has ordered, shielding city residents from bearing the cost alone.

Xcel Energy now projects the extra cost to bury its planned Hiawatha transmission lines at $17.5 million, up sharply from earlier estimates. That represents a mere five cents monthly for a typical residential customer when spread across a multistate area, as the Minnesota Public Utilities Commission ordered Thursday. But the tab could have amounted to almost $3 monthly if city residents bore the cost alone, according to Xcel filings.

The twin 115-kilovolt lines will be buried under E. 28th Street between a new substation near Hiawatha Avenue and another new substation on Oakland Avenue, part of a utility effort to bolster service to the area.

Preliminary work has begun, with construction of the lines to follow this summer. The lines are scheduled to be completed in fall 2013, with the substations done by mid-2014, when the line is supposed to be in service.

Xcel proposed spreading the incremental cost of the burial over its entire northern division customer base in Minnesota, the Dakotas, Wisconsin and a small part of Michigan.

The city of Minneapolis, Hennepin County and the Midtown Greenway Coalition all supported Xcel. All three earlier argued against another Xcel-proposed alternative, the cheaper route of running the lines overhead along the greenway, a commuting and recreational trailway for bikes and pedestrians.

The commission approved the buried route under 28th Street this year, but commissioners reserved the issue of who should pay for the extra cost for a special hearing.

Steve Brandt • 612-673-4438