Those in the control room are employees of a quasi-governmental entity called ERCOT, the Electrical Reliability Council of Texas.
ERCOT's job is to make sure the power doesn't go out in Texas. The agency operates and maintains Texas' electric grid, which serves 85 percent of all of the state's electricity users and covers 75 percent of the state's sprawling geographic area.
As the first hot days of Texas summer count down to the scorching temperatures of late July and August - San Antonio hit 100 degrees more than once last week - ERCOT managers say the grid is prepared. It's ready to meet the demands of 20 million Texans; ready to deal with another peak day like that of Aug. 7, 2003, when the state's electrical usage reached a record 60,095 megawatts; and ready to deal with emergencies.
Most Texans knew little of the grid until August 2003, when the nation's largest power outage caused blackouts in the Northeast. Studies of the outages indicated problems in Canada cascaded into the Northeast, leaving New York and Detroit without power for days.
Texas, residents were told, is protected from power outages outside the state because the system isn't connected to other major grids in North America. The Texas grid covers the state except for parts of East Texas, the El Paso area and parts of the Panhandle.
"It's true - the Texas grid is isolated from every other state, so what happens in other regions will have no effect on us," said Mitty Plummer, associate professor of engineering technology at the University of North Texas.
The grid consists of the biggest power transmission lines - lines strung from big steel towers - that carry as much as 345,000 volts. Those lines take power to substations operated by such utilities as CPS Energy in San Antonio, which then distribute electricity to homes and businesses.
ERCOT is responsible for making sure electric generation across the state matches the load, or usage. It's a delicate balancing act to manage the scheduling of power.
At ERCOT's control centers in Taylor - a bunkerlike building designed to withstand a Force 3 tornado with winds up to 206 mph -- and its backup center in Austin, computer programs help workers monitor electrical generation and usage.
On a recent day at ERCOT's Austin control room, it was quiet as about half a dozen workers monitored the system.
But if there's an imbalance between power generation and usage, "things can get pretty tense and challenging," ERCOT spokeswoman Dottie Roark said. "It takes a certain kind of person, because they can't go out to lunch or dinner. They pretty much live here for 12 hours." Experts in the control room closely monitor frequency - the heartbeat of the system - that reflects the relationship between electrical generation and usage. At 60 hertz, generation matches usage exactly. Second by second, 24 hours a day, control-room experts strive to keep Texas' grid as close to 60 hertz as possible.
Its control room uses sophisticated computer programs that forecast demand, plan for emergencies and make adjustments. The 60 hertz goal is just "a continual target, because every time somebody flips a light switch, it changes," said Paul Wattles, ERCOT's manager of governmental relations and communications.
There's constant communication between ERCOT and every utility that's part of the grid, including CPS. If CPS needs to take a line out of service, it tells ERCOT, which turns to another electricity provider.
"ERCOT is digesting real-time data from everybody, and they'll change generation patterns to match the load," said Bill Woolsey, assistant chief transmission operator at CPS.
If there's a drastic, non-routine mismatch - too much usage and not enough power generation, or vice versa - "it can cascade into a lot of problems," Woolsey said. "We would have to start interrupting customers" or cutting power.
Weather patterns provide big clues to power usage.
"At ERCOT, we're obsessed about the weather," spokeswoman Roark said, because the system needs to be ready to respond to demand.
Stable as it is, the Texas grid could be threatened by a huge storm, by multiple equipment failures or by terrorism.
In a presentation last year to the Texas Legislature, ERCOT officials said the grid is prepared for emergencies regardless of cause.
"We could lose any single, major element of the system -- one outage caused by a tornado or sabotage -- and it wouldn't put us at risk," said Kent Saathoff, ERCOT's director of systems operations.
It would take a massive, coordinated, simultaneous, forced outage - basically an act of war - to bring down the Texas grid, a key ERCOT official has told a Texas Senate committee in response to a question about terrorism threats.
ERCOT also continually examines the grid's reserve margins of power - the gap between available power and forecasted usage.
"We make sure that even if we hit a peak we have enough power to meet the demand," Roark said.
But there's some concern that the gap isn't wide enough.
As recently as 2000, the Texas grid had a "huge surplus" of more than 30 percent, Wattles said.
"Right now, we're at about 16.9 percent, so we're still at a comfort level," he said, "but we may drop to the 13 percent range next year. If we get below 12.5 percent, we have a problem." ERCOT believes so-called merchant operators soon will invest in power generation, bringing mothballed plants online or building new ones.
Merchants plants typically are generating stations that burn natural gas to create electricity. A number were built about a decade ago, when natural gas was cheap.
Many of the plants were mothballed as natural gas grew more expensive, but under current conditions, "we should see more investment soon," Wattles said.
ERCOT is still in the process of dealing with an in-house storm. The Legislature ordered audits of its accounting after six men, five of them ERCOT employees, were accused of bilking ERCOT for more than $2 million in services they didn't deliver.
A Williamson County grand jury indicted the six, who are awaiting trial.
No evidence ever indicated the reliability of the grid was ever threatened, but "we won't have this completely behind until 2006," Wattles said.
At the top, ERCOT has a new CEO, 30-year industry veteran Tom Schrader, who signed a three-year contract a year ago.
Little has changed for control-room employees, who monitor, watch and wait - directing traffic on the grid that so many Texans depend on.
And Texans probably won't have to worry when they turn down their thermostats this summer.
"We expect to break the old usage record," Wattles said. "It'll probably happen in August, between 5 and 6 p.m." The grid can take it.