. . . The voltage was unified
The people running the EU demanded that there was a single standardised voltage across the entire EU which (IIRC) had at the low end 220v 10a on the continent and at the high end 240v/13a sockets in the UK.
This matters because 220v *10a = 2200watts, whereas 240vv * 13a = 3120watts, making any device made for the latter system potentially one third more powerful and effective than the former, meaning companies based in the former bleating about it being unfair that nobody in the latter countries wanted to buy their electrical equipment, because who wants to buy a kettle, toaster etc which takes a third longer to get the job done? The solution is of course to ban the latter. :/
Hence bureaucratic warfare being waged to bring everything to one standard. The electricians given the job of picking the standard knew that scrapping an entire electric generation infrastructure would cost literally (tens or hundreds of) billions with nothing to show for it, and pragmatically said that the new requirement was 230v with tolerances that covered both the 220v and 240v systems normal fluctuations.
Thus on paper we are supplied 230v and in theory new generators are specced to this voltage. However, anything existing that is supplying 240v (ie, everything before the regulation was installed; which is almost everything) is still supplying 240v. (my work UPS's are receiving 240v, for reference)
So if your getting supplied 230v then your probably getting it from something connected to the grid recently (ie a wind farm), whereas if your getting 240v then your getting it from nuclear, gas, coal etc which generates the majority of the UK's power, and was probably installed a couple of decades before the regulations came along.
Biting the hand that feeds IT
