A glitch in Xcel Energy's saver's switch system mistakenly cut power to air conditioners in Sioux Falls on one of the hottest days of the summer so far. And with a high temperature near 100 degrees that day, it didn't take long for heat to build up inside homes. 

The hum of air conditioners is a familiar sound of summer. But for some Xcel Energy customers in Sioux Falls, last Tuesday, that familiar sound was replaced by a ringing phone. 

The energy company called each of the customers affected by its saver's switch malfunction with a pre-recorded message apologizing for the mishap, which cut power to 300 air conditioners across the city, including Troy Schmidt's. 

“Came home and it was almost 80 degrees in the house and so I went down and checked the fuse box and that was all in tact,” Schmidt said. 

Instead of making Schmidt's air conditioner operate in 15 minute intervals, his switch cut power for most of the day, filling his house with heat. 

“So then I called Xcel and they said there was a problem with the saver's switch and they'd have it remedied shortly,” he said. 

A saver's switch is supposed to prevent power outages by allowing Xcel Energy to reduce consumption during peak times. But company officials say they've fixed the problem and people who have a saver’s switch installed on the side of their house shouldn't be worried. 

“It was actually the electronic activation so we didn't have the problem with the switches themselves,” said Xcel Energy Spokesman Jim Clark. Clark says power was restored to all of the affected air conditioners by 8 p.m. that night. “There's just one certain brand that we had a problem with so we identified what caused it and fixed it right away,” he said. 

“I've had saver's switches for 14 years, its a good program and I've never had an issue with it,” said Schmidt, who isn’t letting the power problem bother him much. That’s because, once again, he's able to escape this summer's heat simply by heading inside. 

So far this year, Xcel Energy has only used the saver's switches twice to control the use of energy in Sioux Falls. Having a switch can cut your summer electric bill by as much as 15 percent.