One of the hottest days on record in Central Maryland spurred electric power managers Friday to ask Marylanders to cut their demand for electricity in order to keep the juice flowing.
But not everyone was happy about it.
Many customers whose air conditioners were cycled off and on under BGE's Peak Rewards program called the utility Friday to complain about the rising temperatures in their homes or to opt out of the program. Some found they were unable to speak with anyone.
"I guess I'm really fortunate that I don't have any sick people or old people living here," said Michelle Carras, 45, of Ellicott City, whose home was 88 degrees at about 7:45 p.m. "My plan is to get this thermostat out as soon as possible."
"The fact that I couldn't keep within a 5-degree shot of 78 makes me not want to enroll," said Andrew Cizek, of Crofton, who also participates in the Baltimore Gas & Electric Co. program.
The utility responded Friday evening by suspending plans that require participants to have their air-conditioning compressors switched off for 75 percent or 100 percent of the time the program is activated. Instead, everyone was moved to a 50 percent plan.
"This transition will help the utility keep the electric system balanced during the extreme heat, while beginning to moderate the impact on our customers," the company said in a statement.
It was a brutal day to have an air conditioner switched off for any amount of time.
The mercury climbed to 108 degrees downtown, according to the National Weather Service, with a heat index topping 120 degrees. It was the hottest reading ever in downtown Baltimore, but not an official record because, since 1950, the city's official temperature has been measured at BWI Marshall Airport.
The mercury at BWI Marshall reached 106 degrees, melting the 101-degree record for the date, set in 1957. It was also the hottest day on record for the airport, and the second-highest official temperature ever for Baltimore, just short of the all-time record of 107 degrees, set July 10, 1936.
The National Weather Service forecast calls for a high on Saturday of 103 degrees downtown, and 99 degrees at the airport.
Despite the near-record temperature Friday, from BGE's cool, quiet and cavernous Transmission Systems Operations room, you'd never know anything unusual was going on outdoors.
Deep in an unmarked, high-security building in Woodlawn, under subdued lighting, a handful of system operators and supervisors sat beneath a huge schematic wall map of the BGE system.
Calmly, they watched computer monitors that reported the performance of generators and heat buildup in transmission lines. They chatted by phone with regional power managers in Valley Forge, Pa., and repair crews in the field. And they worked to anticipate and plan for any potential trouble.
The scene was about as dramatic as watching grass grow. But Ed Carmen, BGE's manager of transmission system operations, said it was the kind of day his people train for.
"It's probably a little more exciting than more typical times," he said. "There are more alarms coming in that need to be investigated."
There was plenty going on. Demand for power to spin fans and keep air conditioners humming was huge and climbing.
On Thursday, consumers on the PJM Interconnection — the 12-state power grid that serves 54 million customers, including BGE's — had broken a 2006 peak-usage record. Electrical demand climbed to 158,450 megawatts. One megawatt is enough to power about 1,000 homes.
By Friday morning, the mercury was again rising into the low 100s, with high humidity across the Mid-Atlantic states. PJM's power managers saw that the demand for electricity in Maryland, Delaware, New Jersey and Pennsylvania was "outpacing what we had forecast," said PJM spokesman Ray Dotter.
"Hot weather like this really tests the system," he said. "It makes sense to have people cut back if they can."
About 10 a.m., they called on businesses, industries and large institutions throughout that region — all paid participants in a PJM load management program — to curtail their demand by noon. Among those that responded were the University of Maryland, Baltimore; the University of Maryland, Baltimore County; Towson University; and the Johns Hopkins University.
"We can call on them up to 10 times a summer, for six hours at a time," Dotter said. "That gets us from noon to 6 p.m., the peak use time for the afternoon."
The program helps to maintain the reliability of the grid without the need to build expensive new "peaking" generators that might only be used on a few days a year, Dotter said.
At 11 a.m., PJM called on another group of industries and large users in Maryland participating in a similar load-management program to make immediate usage cuts.
Around that time, PJM also asked BGE to activate its Peak Rewards program, in part because of the heavy load across the grid, and in response to a substation failure Thursday night in Baltimore.
Under Peak Rewards, BGE sends out radio signals that cycle 453,000 customers' residential air conditioners and water heaters off and on at a frequency that consumers have pre-selected. In exchange, customers get a credit on their summertime utility bills, whether the system is activated or not.
Cizek, 31, said he signed up to have his air conditioning switched off and on for 50 percent of the duration of an incident. At 6 p.m. Friday, the temperature in his Crofton townhouse was 88 degrees.
Believing he is entitled to override the shutoff if conditions became too uncomfortable at home, he tried without success to reach someone at BGE to ask to be switched on again.
"I'm fortunate. I'm  years old, in really good shape, I've got my fans going full blast, and I'm wearing barely anything," he said. "What outrages me is there's no alternative for people in special circumstances."
Asked if he planned to drop out of the program, he said, "I don't know. … The lack of control makes me not want to enroll."
Carras is enrolled in the 100 percent Peak Rewards program, she said. She reviewed her BGE account information online Friday evening, after she was unable to get through to the company by phone, and the cycling record said her air conditioner had been off for nearly eight hours.
Although the online record indicated that Carras' air conditioning went back on at 6:45 p.m., it did not resume until about 8 p.m., she said.
The Maryland Public Service Commission, which regulates BGE, received nine complaints by phone Friday afternoon regarding the Peak Rewards program, spokeswoman Regina Davis said.
BGE spokeswoman Linda Foy said the company also received calls from customers. "But, to put things in perspective, today's activation was the first of its kind [in terms of being an emergency and the duration] in at least several years," she said. "During that time, customers have been receiving significant bill credits, regardless of whether the program was activated."
The Peak Rewards action typically cuts 400 to 500 megawatts from the demand side of BGE's electric system, Carmen said.
By early afternoon Friday, the big red digits on the wall of BGE's Transmission Operations Center read 6,568 megawatts. If they hadn't activated Peak Rewards, Carmen said, the demand digits probably would have read 6,900 megawatts.
Typical summertime usage runs around 5,500 megawatts, Foy said.
PJM expects more high electrical demand on Saturday, but probably not as high as Friday's since many businesses will be closed.
"The forecast peak for [Saturday] is more than 143,000 megawatts," Dotter said. "That's really high for any day of the week. For a weekend, it's amazing. … We will be watching it very closely. At this time we don't expect to take other actions [to cut demand]. But we'll have to see."
The extraordinary heat took a toll on the region's commuter rail systems, too.
The MARC system was beset with equipment failures that delayed trains and in some cases left riders sweltering in cars stalled without air conditioning. The Maryland Transit Administration reported that the electric wires powering trains on the Penn Line were sagging in the heat, forcing single-track operations between Washington and New Carrollton.
In addition to the usual hot-weather restrictions on the Camden and Brunswick lines, a heat order was issued for the Penn Line holding speeds to 80 mph.
The National Weather Service's excessive-heat warnings remain in effect for Maryland from 10 a.m. to 8 p.m. Saturday, meaning that the risk of heat-related illness remains high for people engaging in outdoor activity.
The Code Red air-quality alert issued by the Maryland Department of the Environment will also remain in effect Saturday. That means air pollution levels in the region will be unhealthy for all groups.
Scattered thunderstorms could produce heavy downpours, flash flooding and damaging winds.
Baltimore Sun reporters Michael Dresser and Steve Kilar contributed to this article.