Same old story everywhere I believe : the fun with standards is there are many.
B22 (Swan's bayonet mount) had an original strong grip on UK (and Commonwealth) and France. But France always used both B22 (and a bit of B15) and E27 (and a bit of E14).
Now B22 mostly remain in usage in UK, India and Australia. France is "converting" (don't know of norms fixing that decision, seem to me it's a market general decision) to E27 since some years (decades), but you will still find some bayonet in old houses/rooms. The majority of Europe uses E27.
I don't have the full history of that, so it looks like a fully purposed mess. For instance I don't know why E26 and E27 both exists same time.
From their sole purpose (electric contact) they are mechanically interchangeables. So maybe it could have to deal with the 110 / 220v standard, because I think E26 is mostly in use in countries which adores 110v, whereas for E27 its 220v believers.Or could it be another cryptic example of metric vs imperial units (where 26mm would be the closest translation of some imperial measure). But this is pure speculation.
This could explain the really poor result at 17. Hyperikon's reference are not clear everywhere.
Well, well, well. Standards. Here we go again :)
Helpfully I have a map for that specific question:
Easy isn't it ? Well, we can still dig in and find more fun. More detailled map:
To each his own, standard, I guess :)
One of the great point of LEDs vs Incandescent or Halogens is that many manufacturers have cleverly took the opportunitu to build worldwide converters (90-250ish) in their bulbs. But not everyone of them.
Very interesting! I've also been recently presented an interesting article (sorry, it is in french) around the design choices of LED manufacturers to achiever High CRI in their chips