Thanks for the inputs.
1) It will be protected in plastic isolation like this:
Must be the cable itself double isolated also inside this?
If not inside that, the cable will be inside the wall and not accessible by normal humans.
When you run a live in anything other than earthed metal containment, you MUST use a cable with an integral CPC (this applies to fixed wiring, not flexes). In practice this is normally 1.5mm2 for single brown and earth, can't say as I've seen bigger.
If you're running it in anything other than earthed metal containment, it must also be double insulated.
Usually it's a good idea to have the neutral along for the ride, to avoid swapping neutrals between circuits by accident, as this will affect the performance of the safety devices in your distribution board/consumer unit..[/color][/b]
2) All neutral wires are blue and live wires are brown. Thank God it is like this is also in this apartment. I will pick a 2,5mm² brown wire for this patch. If you swap a blue wire with a brown one.. well
3) The donor plug and the plug to be patch are behind the same fuse.
I still can't imagine a dangerous situation coming up from this patch, anyway I am here to learn.