"Three-eighty four," Pete Pedersen called out. "Three-one-two-one."

Joe Connolly scribbled the numbers on his clipboard form, as both men sat, cool and serene, before NASA-like control boards.

Connolly and Pedersen are the real power brokers of Washington's hot, steamy summer, with control at their fingertips over virtually every air-conditioner in the city.

Surrounded by slate-gray screens and lighted push-button panels, they sit at the nerve center of Potomac Electric Power Co.

Pederson's figures tell Connolly how much power is coursing from one of the city's six giant generators.

Keeping that power flowing to meet the needs of Washington's sweltering citizens is one of their jobs.

Another is monitoring the buying and selling of electrical power - the constant trade-offs among Pepco and 10 other companies on the eastern seaboard in an effort to provide power at the cheapest price.

August offers no respite for those who do this work. In fact, it is their busiest time.

"I've come to think October vacations are marvelous," said Walter Johnson, who supervises Pepco's control center.

But if Johnson and his employees must work through the sultry August days, at least they are cool.

The temperature in the control room is never permitted to go above 73 degrees. Bad for the sensitive equipment, Johnson said.

The most confortable spot of all, in fact, is the chilled room where Sigma 9 resides. That's the Pepco computer, which is sending out information every two seconds, telling other computers how much power Pepco is generating, at what cost and the amount needed by Pepco customers.

Sigma 9 is in constant contact with a computer outside Philadelphia that ties Pepco to the 10 companies in Maryland, Delaware, Pennsylvania and New Jersey that make up its power trade-off system.

Because nuclear power is cheaper to produce than power generated, like Pepco's, by coal and oil, it is sometimes cheaper for Pepco to generate less and buy from other companies, Johnson explained.

Jagged red lines jumping across graph paper on the control room wall show when Pepco is buying. But the situation changes, almost second by second, Johnson said.

With their eyes glued to the television-like screens, Connolly and Pedersen watch those changes in the world of electronically flashed numbers. Red numbers for transmission lines that are working, blue numbers for "megawatts" flowing through the lines, flashing green numbers in trouble.

Next door, in the glass-enclosed "trouble room," other technicians call up computer reports on problem spots and dispatch crews to make repairs.

Everytime the temperature soars and a suffering citizen flicks on a fan or accelerates the air conditioning, the numbers reflect it in the Pepco control room.

The workers there see the figures on the darkened screens, but otherwise, in windowless basement rooms of a tan brick Montgomery County building, they are cut off from the devastating August heat.

Still, they have their own special ways of knowing when the temperature is climbing or a thunderstorm is moving in.

"You start picking up no-current complaints, fuses start blowing, lines come down," said trouble dispatcher Bill Disney. "You can tell it's humid and hot because the complaints keep coming." CAPTION: Picture, Diagram that outlines electrical circuitry for the Washington area surrounds load dispatcher in Pepco's control room. By Vanessa R. Barnes - The Washington Post