An exposed wire was officially cited as the cause of a charged metal plate that electrocuted a 12-year-old Northeast Washington girl as she played near the Addison Road Metro station June 4, according to a Metro report released yesterday.

The 2-foot-square plate covered one of more than 1,400 electrical wiring boxes in the outdoor, public areas of Metro stations. The report recommended periodic inspections of the boxes and grounding of the wires, which carry power from the stations to parking lot lights and gates.

Metro board Safety Committee Chairman Carlton R. Sickles said Metro should have had a system for inspecting and grounding the wires in those boxes before the accident.

Metro's investigation did not determine how the wire became exposed or came into contact with the plate. The cover was measured at 110 volts before it was removed; the exposed wire measured 260 volts.

An independent engineer hired by Metro said the wiring in the box did not comply with the National Electric Code, which details national safety standards, the report said.

The engineer found that "the intitial wiring installation did not represent a workmanlike condition," the report said.

Other factors contributing to the accident were a heavy rain that soaked the wires, the plate and the victim's feet. The girl was not wearing one shoe, which also was cited as a factor in the accident.