>a lot packed into that comment. A summary: once upon a time, Grand Central Station had AC at multiple frequencies in addition to 60hz (also it had some DC pow

>a lot packed into that comment. A summary: once upon a time, Grand Central Station had AC at multiple frequencies in addition to 60hz (also it had some DC power). In the 1990s it was rewired so that the AC only used the (American) standard 60hz. I suppose its hard to make sense of if you didn't know that 60Hz is the standard in the U.S.?