Duct size from cabinet to plant room

[Thorfun]

Hi all. a few questions on duct sizes please.

 

1. What size ducting should I run from the cabinet on the boundary that houses our 3-phase head to the plant room in the basement?

2. is twinwall ducting ok for this job?

3. I want to be able to run Cat6/6a cable back to the electricity cabinet on the boundary and from there I can run it to the driveway gates or other locations if required. can I run that in the same ducting as the electricity cables or should I run a separate ducting just for the network cable? if so, I assume the standard BT ducting will suffice for that?