Sometimes, Henry Schweizer's wife catches him watching the Weather Channel at their home in Warminster.

Could be a sympathy play on his part. Maybe she'll hear about a coming storm or blizzard or a blistering heat wave, and think, poor Hank, he's going to be working

sooo

hard at Peco, trying to make sure everybody's lights stay on.

Well, sorry, Hank, the jig is up.

Weather like this - it's just plain old fun for adrenaline junkies like Schweizer.

"I love it," he said, as phones rang and dispatchers shouted across the room at Peco's monitoring facility in Plymouth Meeting.

Schweizer, 38, is a distribution shift manager at Peco. He baby-sits the power that runs from hundreds of substations around the five counties into homes, schools, hospitals and companies. Downtown, in Peco's Center City office, other colleagues monitor the power as it comes in on regional grids from power-generating plants to the substations. Once the power is reduced in voltage and leaves the substation, Schweizer picks up control.

It's complicated, especially if you factor in global energy trends and the demand in China for power. But that's not what Schweizer worries about on a hot, hot, hot day like yesterday, when the temperature reached 97 degrees.

Yesterday, it was a Super Fresh supermarket losing power in Chester County, along with some nearby mushroom farms. Lockheed Martin Corp. in Upper Merion phoned to report low voltage in some of its machinery, and 38 customers in North Wales lost their electricity because it was shut off after a contractor mistakenly drilled into a gas main.

"I'm never bored," he said.

He supervises five teams of dispatchers, divided by county, who know the capacity of every substation and transformer in their regions. They sit in a big room, working at huge desks covered with schematics and maps, each desk separated by just enough of a barrier to keep the coffee from spilling, but low enough to make shouting easy. On one wall is a giant computerized schematic of the region's power system.

As long as nothing's red, it's good.

Schweizer came in at 4:45 a.m. yesterday, bracing (well, not really) for a long day. The good news was that buildup of demand on the power system was a slow and steady increase. By yesterday afternoon, there were 401 problems - some involving multiple customers without power and some just a potential difficulty, maybe a sagging electrical line that worried a homeowner.

"It's high, but it's lower than I think it should be on a day like this," Schweizer said. An hour later, it was up to 453 problems, but still that is not extraordinary. On a low day, which is a good-weather day in the spring or fall, there will be 100 or 150 problems.

"We're pacing our crews," he said, dispatching them to the most serious cases first. In a storm or heat situation, the crews, who ordinarily repair the system by responding to routine work orders, become "trouble" crews, a name that could just as easily be applied to other miscreants or a room full of politicians. These crews, however, fix problems.

The reason for the pacing will become obvious today. What really puts a strain on a power system is a few days of prolonged demand capped with a snappy thunderstorm, today's forecast. "We want to be in the best position to respond when the storm hits," Schweizer said.

Yesterday's demand, which hit 8,659 megawatts, was already taxing the system, particularly about 5 p.m. That's when people who were at work all day pull into their driveways and crank up the air-conditioning. Meanwhile, industrial and commercial demand has yet to wind down for the evening. Still, yesterday's peak demand was below the record, set Aug. 3, 2006, when customers used 8,932 megawatts of electricity.

A thunderstorm can put an unpredictable wrinkle into the whole thing, just as it did July 18, 2006, the day of the notorious "Summer Slam," as it is known in Peco world. "We had a long heat wave that ended with a big thunderstorm," Schweizer said. "A couple of hundred thousand people lost their power in a matter of an hour." The actual number was 365,000 on a day that set a record demand for power. Customers used 8,638 megawatts of power on that day, no longer a record.

When that happens, it's up to Schweizer, or whichever shift manager is on duty, to prioritize the calls. Most important, he said, are those from public-safety facilities, such as fire or police. Hospitals rank high, as do sewer and water-treatment plants. "Most of those have two lines coming in already," he said.

Those kinds of customers' problems will outweigh concerns of businesses such as supermarkets. "Nobody's going to die or be injured or put in harm's way if a supermarket loses power," Schweizer said.

Most of yesterday's work involved keeping level the load among various substations. As demand increases at one substation, crews will go out and pull some switches, opening and closing breakers to bring in power from a substation that is experiencing less demand.

Sometimes it's a judgment call. For example, Schweizer had to decide yesterday whether to press on full-bore to repair a problem at a substation near South Street and Grays Ferry Avenue or dispatch crews to places where power was actually off. It would seem like an easy decision, especially since none of the 877 customers in the area were without power. However, one line was doing the work of two, which could pose a problem if today's storm wreaks havoc with the system.

It was a risk, but the Philadelphia regional dispatcher, Don Sciorillo, thought it was worth taking. Schweizer agreed, blessing the decision. He looked at a computerized map. The area covered some of the high-end Center City neighborhoods around 22d and Delancey Streets. "There are some famous people along Delancey," he said. "We definitely know about it when the lights are off."

Contact staff writer Jane M. Von Bergen at 215-854-2769 or jvonbergen@phillynews.news.