I would like to run an underground cable (5x6 mm²) outside. To do this, I need to drill a 2 cm wide hole in the basement wall to run it outside.
This will all be done below ground level. All I know so far is that I need to drill from the inside to the outside downward, so that water doesn't get into the cellar every time it rains.
Now the question is how best to seal the hole with the cable running through it so it doesn't draw moisture into the walls. I would not want to drill a 10 cm diameter hole to seal it with an O-ring seal. There would be no soil in front of the hole, but a gravel pit.