The Environmental Protection Agency found leaking PCB transformers in three Smithsonian Institution museums yesterday during an emergency inspection of 25 transformers and ordered that work to correct violations begin within 48 hours.

If the required corrective action is not taken within that time period, the EPA has the authority to fine a violator up to $25,000 per leak per day, and seek court action including an order to close a building, EPA lawyers said.

The leaking transformers were found in the Museum of Natural History, the Museum of American History and the National Portrait Gallery/Museum of American Art, according to a statement released last night by the EPA. The agency did not report the number of transformers that were found leaking, but said leaks varied from "two feet by two feet" to "a drop to two drops."

The EPA's inspection came two days after the agency published new regulations about PCB transformers designed to prevent a PCB fire, which would create more deadly chemicals, including dioxin-2,3,7,8-TCDD, described as "one of the most toxic substances known to man."

The Hazardous Materials Unit of the D.C. Fire Department discovered evidence that many PCB transformers in the Museum of American History were leaking during a June 27 visit; unit members were asked to leave the building because they had not cleared the tour in advance with institution officials.

Priceless national heirlooms housed in the museum would be contaminated if there were a PCB fire there and experts said the cost of restoring them is incalculable. It would be years before the public could reenter the building, experts said.

The EPA's statement said, "The inspector pointed out to Smithsonian officials that even a drop or two is a leak under EPA's regulations and that the Smithsonian must initiate servicing the violating transformers within 48 hours of the time of the leaks' discovery today."

The Smithsonian had maintained that the fluids are "weeping" or "seeping" from the transformers and do not constitute leaks.

All leaks were in electrical vaults -- protected by steel doors -- that are not accessible to visitors, the EPA said.

The Smithsonian said last night in a prepared statement that it would "initiate repair actions on all transformers that have leaks of any kind whatsoever within 48 hours."

An electrical testing firm under contract to the Smithsonian reported to the institution last month that its inspection had found leaks in 34 of 51 transformers containing the toxic chemical. The report, by Substation Test Co. of Forestville also said that numerous circuit breakers designed to protect the museums against electrical fires were defective and needed to be replaced.

Established by congressional action in 1836, the Smithsonian is exempt from inspections by District government agencies and the General Services Administration, which maintains most government buildings. The local and federal agencies do not have the authority to force compliance with fire and electrical codes.

A District building inspector said yesterday that any building with an electrical system in the condition reported by Substation would be required to make immediate repairs or would be ordered closed.

"Anytime you can't shut down an electric system, that's a major violation," said Vincent Ford, assistant chief of the D.C. Department of Consumer and Regulatory Affairs' building inspection division.

The Hazardous Materials Unit visited the Museum of American History after an employe, who has since been fired for what Smithsonian officials called unsafe work habits and unexcused absences, reported that the PCB transformers were leaking. Lt. Pat Walsh, of the HAZMAT team, said the visit was to determine the locations of the Smithsonian's PCB transformers.

The fire department's list of government buildings with PCB transformers showed only one and gave its location as the Smithsonian castle buiding. Smithsonian officials said there are 57 PCB transformers at seven of its buildings, most of them on the Mall.

D.C. Fire Department spokesman Ray Alfred said earlier this week that because of the dangers to firefighters when PCB burns, "we won't go in unless a rescue is involved."

"We are very concerned about PCBs because they present a number of health hazards to our firefighters upon exposure: the possibility of liver damage, the possibility of sterility, the possibility of birth defects and the possibility of cancer."

The EPA said that when it received the full report from the inspector on the PCB leaks, it will "consider whatever enforcement action may be necessary." No date was set for that report.

In addition to the leaking PCB transformers, the EPA said it discovered violations in storage areas where it found four 20-gallon containers, a 55-gallon container and a 10-gallon container, each holding "PCB contaminated rags and other solid materials. They also found six 5-gallon containers of PCB fluid for "topping off transformers" from which fluids had leaked.

"The storage area did not have proper containment as required by EPA regulations . . . . The violations were in the storage areas, due to lack of proper PCB containment and in the areas where the leaks were not cleaned up immediately," the EPA said.

The Smithsonian, in a statement released Thursday, said it had "implemented the standards and regulations of EPA and OSHA [Occupational Safety and Health Administration] in regard to the storage, handling and cleanup of PCBs ever since those regulations were issued."

Inspection of the Smithsonian buildings was conducted two days after The Washington Post reported that D.C. firefighters had found PCB leaks there. On a July 16 tour of several electrical transformer vaults in the museums of Natural History and American History conducted by Smithsonian officials, reporters saw only one 55-gallon containment barrel and four 5-gallon containers of PCB fluid in what officials said was the only PCB storage area.

A source in the union that represents Smithsonian electrical workers said yesterday that after the EPA inspection was announced Thursday cleanup crews had been "working around the clock."

While the inspection was taking place, the source said, workmen continued the cleanup operations in areas the EPA inspector was expected to visit.

To properly clean up the PCB leaks, the EPA requires that all "visible traces" of the known carcinogen be removed. In some cases, EPA officials can order removal of the concrete where the leaks occurred.

Cleanup after a PCB fire is many times more complicated: a state office building in Binghamton, N.Y., where a PCB fire occurred Feb. 5, 1981, has cost $28 million to clean and repair.

It will not reopen until early next year, five years after the blaze occurred in switching gear located in the room with PCB transformers, and soot laden with the toxic byproducts spread throughout the building.

Dr. Richard Ronan, vice president of the environmental consulting firm Versar Inc. that advised state officials in the Binghamton cleanup, said that almost everything in the office building there had to be destroyed because the expense of cleaning and decontaminating was prohibitive.

Asked about the treasures housed in a building such as the Museum of American History, Ronan said that artifacts made of porous materials -- such as the gowns of the First Ladies, George Washington's false teeth and the tent he used during the American Revolution -- present monumental cleaning problems.

Everyday objects made of such materials are usually detroyed because it costs too much to clean them. "If the clothes were worn by George Washington," Ronan said, "It might be thought of differently."

" . . . I'm just sitting here reeling about the things at the Smithsonian," he said. "The Hope Diamond could be saved, but the Star-Spangled Banner would be very difficult."

"We are not just dealing with the papers of Mrs. McGillicuddy's death, we're dealing with things that are irreplaceable."