A record-breaking heat wave is straining Utah's power grid, with outages reported in Salt Lake and Box Elder counties Monday.
An electrical line went down near 6600 South and Wasatch Drive, and that knocked out Utah Power's Casto substation at 3300 East and 6000 South. The substation, serving 2,000 homes and businesses, was out of service from 5:55 to 7:40 p.m.
"It may have been related to heat," Dave Eskelsen of Utah Power said. "Sometimes when there's heat stress on the system, a splice or a connection will fail."
A power outage in Perry, Box Elder County, "was also heat-related," he said. "One of the circuits in the substation was at its thermal overload," causing the system to fail.
Scorching temperatures prompted Utahns to crank up their air conditioners and swamp coolers, and that caused at least three problems: the volume of electricity used threatened to overwhelm local power circuits; it drained energy from a stressed system; and it heated up already hot equipment that was approaching thermal overload.
In southern Nevada, triple-digit temperatures and power plant problems contributed to rolling blackouts for the first time in that state's history. California issued a power alert Monday, triggering federal price caps.
Parts of Utah were just as hot, with records set throughout the state.
Places where highs hit the century mark included Salt Lake City, 100 degrees; Orem, 104; Provo airport, 100; Provo at the Brigham Young University campus, 102; Springville, 100; Utah Test and Training Range near the Great Salt Lake, 102; Wendover, 100; Coalville, 100; Heber, 102; Hanksville, 105; Delta, 106; Milford, 101; St. George, 111; Zion National Park, 107; and Morgan, 100.
Page, Ariz., reached 103, so the heat at the nearby Utah resort of Bullfrog on Lake Powell likely reached 105.
On Tuesday and Wednesday, "it's going to be about as warm as it gets around here," warned Dave Sanders, lead forecaster at the National Weather Service forecast center on North Temple.
Salt Lake City's temperature is taken at the airport, where the forecast calls for 102 both today and on the Fourth of July. If that turns out correct, today will be a record (the previous high for July 3 was 101 in 1985) while Wednesday will tie with July 4, 1936.
The airport often is a bit cooler than other parts of Salt Lake County.
A ridge of high pressure is parked over the Utah-Nevada border. Such a ridge causes "the most favorable situation for getting warm air at the surface," Sanders added.
Starting on Thursday the ridge should shift toward Colorado, tempering the heat and possibly prompting thunderstorms.
If the temperature does reach 100 in Salt Lake City Tuesday, that will be the fourth day in a row when the thermometer reading reached three digits.
Scorching heat prompted Utah Power to issue its first yellow alert, asking residents to power down their big appliances until after 8 p.m.
"We do think our conservation messages and the Power Forward program are producing good results," Eskelsen said.
Unfortunately, reducing the work of an air conditioner can be harmful to some people.
People become ill when it's very hot outside if their body temperature control system overloads. Normally, the body cools itself by sweating, but that may not be enough. Very high body temperatures can damage the brain or other vital organs, according to the Centers for Disease Control and Prevention.
Humidity can slow down evaporation of sweat. And other factors, including old age, obesity, fever, dehydration, heart disease, poor circulation, sunburn and drug and alcohol use can also prevent the body from regulating its own temperature.
Those at highest risk for heat-related illness are infants and children under age 4, people older than 65, people who are overweight, those who overexert and people who are already ill or take certain medications.
Warning signs of heat stroke include extremely high body temperature, red, hot, dry skin and no sweating, rapid and strong pulse, throbbing headache, dizziness, nausea, confusion and unconsciousness. Heat exhaustion symptoms include heavy sweating, paleness, muscle cramps, tiredness, weakness, dizziness, headache, nausea or vomiting or fainting. Left untreated, heat exhaustion may lead to heat stroke.
Wear lightweight, light-colored, loose-fitting clothing and a hat if you're outdoors. Sunscreen is crucial.
Don't overexert and, if possible, stay indoors in an air-conditioned area. If you don't have air conditioning, consider visiting a mall or a shopping center that does. Remember that a fan will not prevent heat-related illness when the temperature is in the high 90s or above. And avoid alcohol.
Contributing: The Associated Press