[Solved] Choosing the Right Drill Bit Size for Running 7 UTP Cables Through Wall with PVC Pipe

Hello

I need to run 7 utp cables through the wall, I need to drill a hole in the wall.
Into the drilled hole I would like to insert a pvc pipe first so that the cables do not come in contact with the wall.
What width of drill bit should I choose?
I did a quick calculation, the cable is 5mm in diameter and so:
2.5mm*2.5mm*3.14*7=137.4mm^2 - area of 7 cables => diameter of the hole(drill bit)
must be at least 13.2mm ie drill fi 14
Knowing that the cables will not perfectly adhere, so let's give 20% allowance.
It comes out drill bit 17.
Theory is theory and practice is practice, so I turn to more experienced colleagues.
If I make a hole fi 20 is enough? I need to buy a drill for 600mm and I would not like to buy another larger one later or drill next to the hole because it is an additional cost no and unnecessary drilling.

Greetings

Hello
A peszel is e.g. 16mm/20mm/22mm as protection from touching the wall of your wires and a twisted pair is not such a thick cable even in the screen,It is probably 8x,12x and I do not know if not more.
PS.The drill has a diameter (fi)

Twisted-pair cable 8x, classic, diameters of 5mm I gave as the whole cable(from the manufacturer's website).
What cover is better to insert a flexible peszel or rigid electrical conduit?

Hello.What you will want,but I think the peszel because it is more flexible and corrugated surface to avoid stresses.

Thank you for the hint, I know it's a simple job but it's better to ask and not correct after yourself later
Greetings