ᐅ Chasing walls for wall lights

Hello everyone,

I hope this is the right place to ask.

I have purchased a house built in 1992. The exterior walls are 17.5cm (7 inches) hollow bricks, the red ones.

Now I want to install two wall lights on a wall in the living room (an exterior wall). For this, I planned to chase a horizontal groove about 15cm (6 inches) below the ceiling, approximately 4 meters (13 feet) long.

I recently came across some guidelines online regarding chasing grooves in walls. This has raised some concerns for me.

Is it safe to execute the groove as planned? What alternatives are there? The ceiling and floor are finished and should not be damaged.

Thank you in advance.

Alternative: Flush conduit directly under plaster, not chiseled in, only glued or nailed

The plaster thickness might be sufficient for the building year. I would do it that way as well. But use standard NYM cable instead of a flat cable.

I can't fit the standard NYM cables inside the plaster. What are the disadvantages of using flat cables?

If you can maintain the required 10mm (0.4 inches) plaster coverage for the conduit, then you might as well just install NYM cable.

Why the 10mm (0.4 inches) plaster coverage?