David Billington wrote:

Why limit it to France, AFAIK all of Europe is 50Hz and would give those
speeds. Must be some historical thing but when I moved back to the UK in
1982, many people seemd to be of the opinion that the US still ran on DC.

Back in the late 70's Japan was 50Hz in part of the country and 60Hz in the
rest. Don't know if they harmonized it by now.

Wes