The Fairfax County Board of Supervisors voted on subjects ranging from land use to larger street signs yesterday in its last full meeting before the Nov. 3 election that will decide the board's future composition.

Among the decisions made was one designed to guide development on a key 30-acre tract in Reston. The vote on street signs will make them bigger and taller and change them from the familiar green to blue in the name of better legibility and permanence.

Yesterday's meeting was the last until January at which the board will address new land-use matters. The moratorium, which the supervisors agreed to impose on themselves in accordance with tradition, is designed to take politics out of zoning and land matters before the board that is elected in two weeks is seated in the new year.

In the Reston case, the board approved a plan to reduce the amount of office development permitted on 30 acres that was formerly the site of the A. Smith Bowman Distillery, maker of Virginia Gentleman bourbon.

The distillery's decision to leave Reston last summer sparked a bitter debate over office construction planned for the county. A subsequent proposal to severely curtail such development on more than 10,000 acres was defeated but led to an ongoing study of the county's land-use and transportation goals.

The vote on the street signs will bring about replacement of the current green signs over the next three years, at a cost of $2 million.

The new signs will be nine inches wide with white six-inch letters on a blue background and stand on 10-foot steel posts.

The ones now in place are six inches wide, have four-inch lettering and stand eight feet above the ground.

County officials said the larger signs will be easier to read and be less of a target for vandals.

Supervisor Martha V. Pennino (D-Centreville) said that blue signs, already in use in Reston, "don't fade into the foliage and fauna. And blue also reflects better at night."

Commented Supervisor Tom Davis (R-Mason) "They're going to be harder to steal now, aren't they?"

Top priority will go to replacing street signs on major roads, then in subdivisions.

In the subdivisions, the replacement will take place first in southern and eastern Fairfax, where population is most dense.

Larger street signs are already in use at about 150 intersections that have traffic lights on the state's highway system in Fairfax.

The new street signs reflect a nationwide trend, County Executive J. Hamilton Lambert said in a report to the supervisors.

The developer of the 30-acre Bowman Distillery property, in one of the county's hottest areas for development, has plans for an office building of more than 900,000 square feet and had asked the board to postpone yesterday's vote.

The plan approved by the supervisors, which Reston civic leaders praised as appropriate, calls for allowing about 650,000 square feet of office development, or a mixture of about 650,000 square feet of office development and 325,000 square feet of residential development on the land.

The board asked the county staff to propose zoning revisions in line with the reduced amount of development considered permissible. Zoning now in place permits a variety of heavy industrial and office uses.

The board's action recalled the debate over the proposal, defeated last December, to broadly curtail permitted office development throughout the county.

That proposal was aimed at the key issues of growth and transportation, which are central to the current supervisor election campaigns.

In other business, both the Fairfax and Loudoun County supervisors voted without dissent yesterday to accept petitions from landowners around Rte. 28 near Dulles International Airport to create a special taxing district to help finance widening the two-lane road to six lanes.

The Fairfax supervisors agreed to hold a public hearing on the proposal Nov. 30; the Loudoun supervisors set a public hearing for Nov. 23.

The Fairfax supervisors also agreed to spend $100,000 to initiate a study of the possibility of the county taking over secondary roads now administered and maintained by the state.

The study is expected to be completed next May.