Patients at The Laurels and The Haven in the Village at Carolina Place were evacuated onto Charlotte Area Transportation System buses and Medic casualty buses to cool off.
Fire officials said the temperature was about 80 degrees inside the cafeteria where residents waited for buses to arrive.
Officials said a transformer blew out and knocked a power line to the ground around noon, causing an outside fire.
Duke Energy cut the power to that line which cut power to the assisted living and memory assistance facility.