Fire in an electrical control and distributed room knocked out most of the power at Sibley Memorial Hospital yesterday, curtailing surgery and reducing heat circulation, fire department and hospital spokesmen said.

The fire, which caused an estimated $20,000 damage but no injuries broke out at 6:56 a.m., officials said. Power was restored at 6:30 p.m., according to a hospital spokesman.

In the interim, the fire department supplied emergency power, a fire official donated blood to a patient who suffered a hemorrhage, and hospital staff and volunteers carried meals up as many as six flights of stairs because elevators were not working.

The 362-bed hospital suffered no major problems as a result of the blaze, and was able to care adequately for its patients, according to spokesman Melvin B. Shivar.

He said the major effect of the loss of power was in restricting surgery to "emergency or extremely urgent cases." All scheduled surgery that could be postponed was postponed, he said.

Battalion Chief Francis X. Flaherty, the fire official who gave blood said the fire in the 20-by-40 foot sub-basement electrical panel room was attributed to an overloaded circuit.

Shivar said the room contains equipment for control and distribution in the hospital of electricity coming from two outside feeder lines.

A spokeswoman for the Potomac Electric Power Co., said she understood that 12 hours were required for repair because the damage "was so extensive."

Although the fire knocked out connections to the operating room from an auxiliary diesel-powered generator, Shivar said, a second backup system, powered by batteries, remained available for the operating room.

The spokesman said the intensive care unit received power from a second auxiliary diesel unit. Other essential services were fed from the 26,000 watts provided by D.C. Fire Department generating equipment.

Neither cooking nor heating facilities were electrically powered, the spokesman said, and remained in operation. However, electric fans that circulate the heat were knocked out.

There was "some" decline in temperature in patients' rooms. Shivar said, but it was "not to bothersome levels."

In addition, he said, except where vitally needed, fights were out in halls and rooms.

Shivar said the condition of the woman who required the emergency transfusions was quickly stabilized. He also said that although meals had to be carried by hand, they were served hot and on a "timely" basis by staff and volunteers.

Lights went out again about 8 p.m. and were restored by 8:30 p.m., according to acting administrator Jay Wolfgang who said the incident appeared connected with the fire. Wolfgang said staff members navigated the darkened corridors with flashlights used earlier in the day.