What is the correct sealant to use to make a seal between a polyethylene-sheathed ethernet cable and a sandstone brick will for exterior applications?

I will drill a 10mm hole between the inside and outside of a sandstone brick wall for a 6.5mm ethernet cable which is 'PE' sheathed according to the cable marking. I assume this is polyethylene. I want to seal the exterior wall side of the cable from water etc.

What type of sealant is weatherproof, and interfaces with both the polyethylene and sandstone brick?

I have looked at available products in the UK, but it is not clear to me what is optimal. Would, for example, https://www.screwfix.com/p/no-nonsense-all-weather-sealant-clear-310ml/7876d be acceptable for this application?

  • 2
    Cleaning the two surfaces is the main thing. Any dirt/oil/dust and the caulking/sealant will stick to it instead of the surfaces and will peel off.
    – crip659
    Commented Jul 8, 2023 at 20:18
  • I would strongly consider running the ethernet inside conduit on the outside at least, to avoid UV degradation at a minimum, and to facilitate replacement. As for a sealant, "metal safe" silicone sealant is always a good first thing to try.
    – Armand
    Commented Jul 8, 2023 at 22:28
  • You can get Ethernet cable with a UV jacket...
    – Huesmann
    Commented Jul 9, 2023 at 12:36


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