Sf has one of them - https://en.m.wikipedia.org/wiki/Trans_Bay_Cable https://en.m.wikipedia.org/wiki/Trans_Bay_Cable On a related note, there was a fascinating

Sf has one of them - https://en.m.wikipedia.org/wiki/Trans_Bay_Cable https://en.m.wikipedia.org/wiki/Trans_Bay_Cable On a related note, there was a fascinating article on sf's dc grids by Spectrum https://www.google.com/amp/spectrum.ieee.org/tech-history/dawn-of-electronics/san-franciscos-secret-dc-grid.amp.html https://www.google.com/amp/spectrum.ieee.org/tech-history/da... (pardon the amp link) My office building taps into it to power the old school loading elevator!