>>44910
>Thanks for your help.
Ofc.
>it was related to moisture.
Needed more time to dry.
>Old wall sockets have no ground at all
Jesus. With lights it's not much of a problem me thinks, but with household appliances... I've a pal who - long time ago - run his pc from a socket without ground. The frame always shocked on touch.
>everything must be broken, from parts of walls to ceiling
Yup. In certain cases they can tie the new wires to the old ones, and when they pull out the old ones they pull the new in with same motion. But considering the condition of old cables, they can tear, and who knows if they are in tubes, or what's the condition of the tubes.
Maybe the simplest is to cut old wires at the connections, seal them off and leave them in the walls and ceilings, and screw plastic channels outside the walls and ceilings where the new cables can run.
A more elegant solution: leave the old cables in like above, and cut new channels into the walls, where new tubes can be put for the new wires. This however a dirty work with dust and debris. So best be done while renovating, as you mentioned.