The State of Virginia, accused by Fairfax County officials of inadequately enforcing construction safety rules, now has accused the county of operating unsafe fire trucks.

The county has "numerous" fire trucks with improper electrical wiring that could electrocute fire fighters, a state safety official said yesterday.

County officials disclosed the alleged violation yesterday at the same time the Fairfax Board of Supervisors formally approved a construction safety agreement with U.S. officials -- a move that is being opposed by the state.

The county turned to the federal government for help after criticizing the state's enforcement of health and safety rules at construction sites as inadequate. Fourteen persons have died in construction accidents in Northern Virginia in the last two years, including two in Fairfax.

Now the state, in a violation notice issued Feb. 14, is accusing the county of operating fire trucks that have inadequate ground connections for electrical generators used to power firefighting equipment, according to John E. Plummer, chief administrator of the Virginia Occupational Safety program.

The state made an inspection after receiving an anonymous complaint.

Fairfax Fire and Rescue Service Director George H. Alexander said the county knew before the state inspection that at least half of its 70 or so generator-equipped trucks were improperly wired and that nearly all of its more than 200 vehicles need better electrical ground wiring.

He estimated it would cost $60,000 in materials and take more than eight months to correct the problems. Plummer, however, said a county official has told state inspectors that it would cost about $2 million and take three years to do it.

Alexander said the county has asked the state to grant it more time to correct the wiring beyond the 30-day limit specified in the violation notice.

"We're going to work with them," Plummer said. "We realize you can't take all the fire trucks out of commission."

County Executive J. Hamilton Lambert, in a written statement to the board yesterday, said the difficulty "may deliver a mild shock to firefighters in wet weather."

Plummer termed Lambert's statement a "gross generalization."

He said fraction of the electricity from the generators could electrocute firemen under wet conditions.