Electricity voltage for Great Britain?

[compman]

I'm having a new electric shower installed. On the box it states: 8.7kW (230V) 9.5kW (240V). So I presume the kilowattage of the shower is based on the voltage of the electricity supply. But what is the standard voltage here in Great Britain, is it 230V or 240V? I always thought it was 240V, but think I also read somewhere that it was being standardized to comply with EU regs.

So what have I got, is it an 8.7kW or 9.5kW shower?

[emeritus]

this should help looks like it remains 240 in the UK

Following voltage harmonization all electricity supply within the European Union is now nominally 230 V � 10% at 50 Hz [1]. For a transition period (1995�2008), countries who previously used 220 V will use a narrower asymmetric tolerance range of 230 V +6% −10% and those (like the UK) who previously used 240 V use now 230 V +10% −6%[2]. Note that no change in voltage is required by either system as both 220V and 240V fall within the lower 230 V tolerance bands (230 V �6%). In practice this means that countries such as the UK that previously supplied 240 V continue to do so, and those that previously supplied 220 V continue to do so. However equipment should be designed to accept any voltages within the specified range, and in practice most do so.

[compman]

Thank you for a prompt reply