It took seven men to cut one tiny ribbon yesterday.

They were politicians, and the red-and-yellow ribbon was strung between a bus and a platform at Beacon Mall on Richmond Highway south of Alexandria for the dedication of the Fairfax Connector, the county's new bus service.

When the 38-seat buses with electronic fare collectors begin their runs today, Fairfax will join Alexandria and Montgomery County in replacing some Metrobus lines with its own transit system.

"We begin with a small acorn I hope will grow into a tall oak," Fairfax County board Chairman John F. Herrity told a small crowd assembled for a half-hour ceremony that included a performance by the West Springfield High School drill team, a bagpipe band and a county honor guard.

For now, the Fairfax routes will replace 10 Metrobus routes to and from the Huntington rail station, the county's only operating subway stop. A consultant has estimated Fairfax's savings at $735,000 in the first year, possibly more in later years.

If all goes well, county officials hope to expand service to include the Orange Line, scheduled to open in Vienna next summer. Some, including Herrity, have expressed hope that it could replace other Metrobus routes in the county.

Herrity criticized Metro yesterday for "horrendous" operating deficits that he said have pushed the county's bus costs from $8.3 million in fiscal 1978 to $25.5 million last year, even though ridership has been fairly level.

One way the county will be able to save money with the new buses, he said, is by eliminating "featherbedding" that is allowed in the Metro system. Metro, for example, hires a large percentage of full-time drivers, even though using a larger number of part-time drivers during the ridership peaks in the morning and evening rush hours would be more economical, Herrity said. Fairfax Connector drivers will be paid less than Metrobus drivers.

As a long line of cars idled at a nearby drive-in bank, Herrity held scissors in hand to slice the ribbon, joined by fellow supervisors Joseph Alexander and T. Farrell Egge, state Sen. Joseph V. Gartlan Jr. (D-Fairfax), state Del. Frank Medico (R-Fairfax), former supervisor Warren Cikins and Alexandria City Council member Robert Calhoun.

Most of those at the ceremony appeared to be local politicians or employes of county government or the new transit service. Watching with a passenger's interest was James W. Gray, 54, a retired government worker who lives off Fort Hunt Road and often takes a Metrobus to the Huntington station when he does part-time consulting work.

"They're got a standard to live up to," Gray said of the new county bus service.