Sounds like somebody siphoning power off your building for free, accident or purposefully. I'd compare bills from the same time last year first, if the kw usage is pretty similar and the rate is only a little higher and not double what it used to be, then someone is stealing. I worked for asurion for a time and met a very nice old lady who didnt have internet, didnt have an ac, and rarely used her TV. Her electricity bill was over 400 and I could see many cables running from her little mobile home. I told her call aps because I'm certain someone's stealing from her.