On 04/03/2019 00:43, Roger Hayter wrote:
I don't know when the last public DC mains supply was replaced, but I
tend to think that AC/DC TVs were actually designed to work on DC mains
up to the early 1950s at least.

There were DC mains supplies to the late 1970's in areas like London's
West End which were used by the theatres for arc lamps. Apparently also
used for many lift and escalator motors. University College London used
it too, and not just in their (at the time) Bloomsbury Theatre. We had
220VDC mains sockets in the physics labs, which I used for a carbon arc
lamp at one point. (The sockets were like 15A round pin sockets, but the
earth pin was nearer to the live pins.) By 1983 (and probably a year or
two before), the DC mains supply had ceased and it was generated locally
on site instead.

Of course, DC supply was something specialised at this point, and not
provided to standard consumers - only those with a specific requirement.

--
Andrew