According to the old, no longer valid standard, a non-metallic unbreakable pipe having a lightness (inside diameter) of min 29 mm had to be used for the hidden lightning rod.
This standard has not been valid for many years, but still many people demand pipes.
As a producer, we recommend using pipes with a medium mechanical resistance of 750N / 5cm.
The most suitable flexible wiring pipe is SUPER MONOFLEX 1240, which has an internal diameter of min. 31.2 mm.