Energy Audit

Con Edison does something called an energy assessment.

https://www.coned.com/en/search?search=Energy%20audit

Keith Burkhardt
TBG

Is it just your last bill, or has it been a trend of recent bills?
Have you lived there for years so you have a general idea of normal seasonal bill size or is this a new place?

ConEd sometimes does estimated bills for months and months if they lack easy access to meters in your building. You can then get hit with a big surprise bill when they do a reading and the actuals are way out of line with what they estimated. I had a $700 bill like that ~10 years ago. Make sure you check the details in recent bills to confirm.

I also know a guy who had a neighbor doing renovations that somehow were plugged into electrical in his unit which was an interesting story.

steve123,
Go shut off the main breaker by your meter and listen to who starts cursing.

When I worked for Arthur Andersen one client was Brooklyn Union Gas on Montague Street and I learned all sorts of interesting stuff about utilities.