I'm setting up a home ethernet network in a spare bedroom. I envision running up to two dozen ethernet cables out of a patch panel in this room to the rest of the house. I'll likely bundle these cables, punch through an interior wall and down into our crawl space.

How do folks recommend getting this many cables out of the room and down to the crawl space?

When I've previously run single ethernet cables between rooms, I've drilled small holes in bottom plates and sealed up these holes with caulk.

But, to make a hole large enough for 24 cables, I'm picturing having to make a much bigger hole. Sealing a hole this big with caulk seems like a mess, particularly if I have to run new cables in the future. But, if I don't seal the hole, I worry we'll get vermin coming up from the crawl space into the house (we've got a mouse problem).

I've also seen recommendations to place the cables in a pipe or conduit running down to the crawl space. But, it seems you'd have the same problem at the end -- how do you seal the end of the conduit where the cables come out?

  • 1
    In many jurisdictions, there is a code requirement that all holes through the floor plate be sealed with fire resistant foam. This is to prevent fire from moving from floor to floor, similar to requirements for fire block framing.
    – bib
    Jan 26 '19 at 17:22
  • I imagine, on the end of a conduit through the floor, you could put a piece of rubber, like a balloon, that you can seal against the conduit, but will allow for stretch and expansion as needed. Or a plastic hole grommet that has a flexible out like a j-box clamp.
    – Jeff Cates
    Jan 26 '19 at 20:29
  • Thanks both for these informative responses. I particularly like idea of flexible clamp at the end of the conduit!
    – Stinkpot
    Jan 28 '19 at 3:46

Conduit & Patch Panel

If you're patch panel is embedded in the wall, you might need some additional structural support around it. I would make 2 runs of 2" conduit down to your crawl out of the patch panel. The reason for using conduit rather than just plain wires is that it makes a more finished result and will be easier to add new wires/remove wires in the future. It'll also be easier to seal it with fire resistant caulk. Once you get into your crawl, you can just put a bushing on the end to terminate the conduit and run your Ethernet freely. Ethernet is low voltage which allows you to run it how you see fit. However, my recommendation would be to use zip-tie tags to group the cables together by room and use the label to notate which room the cables lead to. You can keep the cables up off the ground with zip-ties with screw mounts. However, it's critical not to over tighten the zip ties as it can damage the cable.

Fire Block

Most places require that all holes between levels of a building be sealed with some fire block. There are several different methods for this, but probably the easiest with fire-resistant caulk. Basically, the job of the caulk is to seal off the cavity so that the fire in one area cannot use the small holes in the cavity to pull air from to fuel itself. When the caulk is heated up, it expands in the hole working to keep a consistent seal. Another purpose is to prevent the fire from spreading up the wire.

  • 1
    Just saw this is a 6 month old question. Sorry for being late to the party Aug 19 '19 at 16:41
  • 2
    No worries and this is still super-helpful! I haven't started the job and will take this into account!
    – Stinkpot
    Aug 20 '19 at 17:37

I would use Conduit with cable management grommet on the living space end and stuff steel wool in the end in the crawl space.

Easy to take out the steel wool if new cable is needed, keeps out mice and voles.

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