Wire WAS preinstalled in the tube - I have photos. And one electrical
engineer in the field told me that this is wrong - tubes should be
laid empty and only later filled with wires. But firms here in
Slovenia often ignore customers in hope that since it takes several
years to get your way in the court people won't put charges against
them. Also corruption is high and they could bribe construction
inspector not to give me right.

John Grabowski je napisal:
I am only familiar with construction codes and practices in the USA. Do you
have a building inspector in your town that you can consult? It is possible
that the wire was preinstalled in the tubes and you might not be able to
pull additional wires into them.

Something else you could do is stop by construction projects similar to
yours and try to see how the wiring is installed or talk to the construction
workers.