Recess electrical wiring in old plank wall

[Processengine]

But then TS will get a fragile single-layer plaster with all its disadvantages.

OSB and rotgips maybe?

 

[Dublin]

I would use ROT boxes, tubing, and fish. Go horizontally as much as possible and choose a few well-chosen places where you need to go vertically over the nogging by removing a board. Note that you need to loosen 3-4 boards so as not to break the tongue. Not that it may matter much if you're going to plaster anyway.

I would probably go with that method. It should be the easiest. What might complicate things a bit is if the walls are filled with sawdust, then it gets a little trickier to get the tubing through. At the same time, I'm confused by the picture where you test-drilled with the hole saw; inside there is modern insulation. But maybe that wall is newer than the rest?

 

[Dr spikskalle]

I would probably use that method. It should be the easiest. The thing that might complicate matters is if the walls are filled with sawdust, which would make it a bit trickier to get the hose through. At the same time, I can't make sense of the picture where you test-drilled with the hole saw; inside there's modern insulation. But maybe that wall is newer than the rest?

The house has been extended and remodeled several times over the years, but that wall is supposed to be original according to the previous owner. I hadn't even thought about the fact that the insulation is of a more modern type. Maybe they insulated it afterward by removing planks and filling the wall.

I've probably settled on trying to fish with a hole and maybe remove a single plank if it gets stuck somewhere.