ᐅ Sealing Sleeve Pipes in Garages: How to Properly Install Conduit Pipes with Annular Space Sealing

Hello everyone,

After searching, googling, and a lot of thinking, I still haven’t found a solution, so here is my question.

For our new build, a conduit sleeve (100mm (4 inches)) was embedded in the basement wall for the electrical installation to the garage. With the appropriate sealing ring, I could of course run the underground power cable and data cable directly through it. However, since I want to make it future-proof, I would like to install empty conduits (1x 50mm (2 inches), 2x 16mm (0.6 inches)) and later pull the cables through or make them replaceable. This is where the problem lies. I can’t find anything suitable to securely seal the (corrugated) empty conduits with the sealing ring. Yes, there are systems designed specifically for corrugated conduits, but I want to keep electrical and data cables in separate conduits.

Does anyone have experience with this kind of situation? Or should I just forget about the empty conduits and lay the cables directly underground?

Regards, Moritz

Hi Moritz,

Compression seals work reliably with smooth pipes, but only to a limited extent and often not permanently with corrugated conduit. Installing multiple conduits neatly and tightly through a 100mm (4 inch) sleeve is technically possible, but prone to errors, especially over the long term. The ability to replace underground cables through conduits is more theoretical in practice; after 10 years, hardly anyone will dig up again for that. Separating power and data cables makes sense, but does not necessarily require separate sealing systems. A multi-service installation would be the technically cleanest solution, even if it seems oversized at first glance. Direct burial is absolutely permitted, but it is permanent.

Good luck!

Thank you for the reply!
So your recommendation would be to install the cable directly underground?

To avoid the issue of “digging up later,” I was thinking of running a short piece of rigid conduit through the sealing ring, then connecting it to a corrugated conduit outside using a coupling. This way, at a later time, a new or different cable could be pulled through without digging. However, I can’t find any products in the sizes I need.

I have a proper multi-utility entry unit for the house connections: Doyma Secura Nova 1.
There is still one spare duct (for gas) available here. Since the representative from the utility company mentioned that protective conduits are also available as extensions, I looked into that.
The system from Doyma seems quite expensive at over €300 for 50m (165 feet) of corrugated pipe plus couplings, but it would probably cover the distance from the house wall to the street and also to the garage.
Would it work to use only the Doyma couplings and then switch to Kabuflex conduit? Or would that be risky in terms of proper sealing, making it better to invest the extra 100–200€ for the full system?

Also, would it be okay to use the gas duct for the electrical and data cables to the garage? Then simply close off the unused conduit with a blanking plug.

I’m surprised that there isn’t a system in common sizes (including smaller ones) that makes this process easy.

Thanks for your help!