A proposed $279 million Fairfax County school budget that would give teachers and other school employes 5.15 percent raises was adopted last night by the county school board.

School board chairman Rodney Page calls the budget proposal -- up $19 million, or 7.3 percent, over current spending -- conservative.

County Board of Supervisors Chairman John F. Herrity predicts that the supervisors, who have the final say on the spending total, "will probably do some pruning to it."

The budget's most controversial element is the proposed 5.15 percent salary increase.

School Superintendent S. John Davis has said that is the maximum allowable under President Carter's wage and price guidelines, and the county supervisors have endorsed the raises as being consistent with those guidelines.

But the Fairfax Education Association, which represents most of the school system's 7,000 teachers, contends that the raises would hardly be sufficient to keep pace with the cost of living.

"It hurts everybody, all the teachers; 5.1 percent is not a lot of money," said FEA executive director John White. "But we look like we're unpatriotic or something to ask for more now."

He said his organization is looking for ways to seek more pay within the limits set down in the guidelines.

The budget proposed for the fiscal year starting July 1 was approved unanimously by the school board. It calls for the county to contribute $180.9 million in local tax dollars, a 12 percent increase over the county's current share of school support.

County Board Chairman Herrity said there is "obviously... some room for cuts... The (county) board probably will make some, but not any deep enough to disturb the quality of education."