A different explanation is that this is a outdated code from when people started using tumble dryers on the same sockets and therefore they "prescribed" 4mm2. On all new installations the practice is to have 2 sockets with 2 seperate 2.5mm2 cables.
You mean that 4 mm2 is intended to supply both washer and dryer, whereas 2.5 mm2 is enough if you have separate circuits? Then it makes sense.
The new instal. are single phase and therefore 6mm2. We do have also 3 phase installations and then it is allowed 4mm2 for stoves.
New installs are single phase whereas old are 3-phase?
How large are the supplies for 1) a flat, 2) a single family house ? (I.e., the rating of the main fuse)
