127/220V systems were common in Europe until the 1950s as 127V bulbs and appliances vanished from the market and any existing systems were modified to provide 220V using hot-to-hot to bring them into line with the 220V 50Hz standard.
These systems pretty much followed a similar wiring arrangement to modern US systems i.e. you had 127V circuits for lighting and small appliances and 220V for heavier appliances.
In some systems, 127V and 220V were metered differently! The 127V supply used exclusively for lighting and charged at a lower rate to compete with the gas companies.
After WWII there was a huge rebuild of power infrastructure in Europe as vast amounts of it, particularly the distribution and transmission systems were destroyed. At that stage, most of the local power companies ended up being nationalised to allow major re-organisation and re-building of networks.
At that stage, everything was standardised at 220V 50Hz which had already become the de facto standard and was the most common system in use (the UK opted for 240V 50Hz for some reason...).
The old split phase systems were simply abandoned.
They remain in use in some former European colonies e.g. you can find 127V in service in parts of the Caribbean, some countries in the middle east and far east etc.
In Europe it was just considered to be of no practical advantage to have two voltages in a home. 127V doesn't really provide any great safety advantage over 220V and it makes wiring more complicated and creates complications in the appliance markets too i.e. you had to know if your appliance was 220V or 127V, rather than just buying any appliance and plugging in and it works. There is also a preference for TN-C grounding and a dislike of floating neutrals. So, in general hot+hot socket outlets are not allowed in modern building. Hence the demise of 127V
Standardisation towards 230V happened in the 80s and 90s to bring the UK, Cyprus and Malta into line with the rest of the European Area (not just the EU).
Northern Ireland has used 230V 50Hz for decades as it sat between Great Britain (240V) and the Republic of Ireland (220V) and appliances from both areas ended up on the market up there. So, it made sense.
230V 50Hz is now the nominal voltage for low voltage supplies in Europe.
Last edited by djk; 11/16/08 09:01 AM.
