Residents in a large swath of Denver---from I-70 in the north to Alameda in the south, and between Broadway in the west and Peoria in the east---are being asked by Xcel Energy to conserve power in the coming days. The request follows the explosion and resulting large fire at an electrical substation at 14th and Jackson streets earlier this week, and is intended to help avoid the possibility of 30- to 60-minute rotating, controlled outages in the area, according to 9News. It could be weeks before Xcel claims an official cause for the blast, which cut power to 31,000 homes. Were too many air conditioners maxed out? (It was the hottest day of the year, after all.) Not necessarily, says Xcel spokesman Mark Stutz. "In fact, it probably wasn't the weather. Equipment fails when it fails," he tells The Denver Post. Meanwhile, another, related investigation is underway---this one of the environmental sort. Denver Health Medical Center and the Environmental Protection Agency admit they failed to collect air samples at the explosion site until about eight hours had passed, writes CBS4. Neighbors like Adrienne Anderson, an environmental advocate, are concerned about the potential impact of the pollutants contained in the plume of black smoke that billowed from the site.