Kitchen installation plumbing and electricity preparation
In the US the wiring just needs to be protected, normally by 1/2 inch plywood or Sheetrock. With that said the wiring is also required to be 1-1/4” back . If the wires are covered with conduit that would also work. ( not sure what you mean by tunnel). 

Added:
With a closer look at the outlet you are not in the us so this may be ok your location would be helpful.