electric shower

[ban-all-sheds]

It is officially allowed to rise to 253V.

I know, but you don't use it for design purpose, you would use 230V.

Never mind that - what about the answers to my questions, or have you got the point?

But I do think my point about the 253V is valid.

Let us assume that a manufacturer produced a shower rated at 11.25kW at 230V.

That's 48.9A.

You might quite reasonably put that on a 50A breaker.

If the voltage should legitimately rise to 253V, that shower would draw 53.8A.

Problem? Maybe not.

Ideal? Certainly not.

Should you design for it? All I'm saying is that there may be cases where the 230V calculation puts you so close to the edge that a within-regulations voltage rise pushes you over, and it's worth a quick check, and a bit of thought about whether you should back off a bit.