On Tue, 29 Sep 2020 20:58:34 +0100, No Name wrote:

3kw immersion heater = 12.5amps !

you are using 240 V in your I = P/V calculation.

Due to EU hamronisation, system voltage is now closer to 220 V so that
makes I = 13.63A......

Except that it wouldn't as the resistance of the element doesn't
change.

240 V and P = 3000 R = V^2/P = 19.2 ohms

220 V and 19.2 ohms I = V/R = 11.45 A and P has also dropped to
2520 W

--
Cheers
Dave.