I live in a building in downtown NYC near Canal and Broadway. It was built in the 1890s and our Otis freight elevator is supposed to be one of the oldest operat

I live in a building in downtown NYC near Canal and Broadway. It was built in the 1890s and our Otis freight elevator is supposed to be one of the oldest operating elevators in the city. The first passenger elevator (also and Otis) was installed in 1857 around the corner on Broome and Broadway. Our elevator is powered by a DC motor. Until a few years ago, Consolidated Edison, who championed DC back in the day, delivered DC to power the elevator. Over the course of a decade or so, in an effort to get us to switch away from DC, they raised the price and in the end it was less expensive for us to install a rectifier in our basement to convert AC to DC to power the elevator. The rectifier is a nondescript box about he size of a small refrigerator and emits an audible 60Hz hum.