ᐅ Use of empty conduit from basement to ground floor / flush-mounted electrical box clogged

Hello everyone,

I have to start right away with a question.

Recently, we got fiber optic internet installed for our single-family house, built in 1972. The network termination point (NTP) is located in the basement; I would like to have the router with built-in optical network terminal (ONT) on the ground floor.

The good news: there is an empty conduit from the basement to the ground floor where copper cables used to run for the telephone connection (which I have used rather poorly for DSL).

My plan: to pull a fiber optic cable through the empty conduit from the basement to the ground floor. So far, so good.

Unfortunately, after opening the outlet box, it turns out that the conduit going downwards is filled with sand and small stones.

Does anyone have an idea how I could still use it? The pictures are attached.

Best regards,
Dennis

If there really is an empty conduit leading to the basement, it should also be visible at the basement ceiling. From there, try to clear the conduit using a wire.
In the switch box, only the stub of this conduit is visible, but no actual pipe.

Knöpfchen schrieb:

If there really is an empty conduit leading to the basement, it should also be visible at the basement ceiling.
From there, try to clear the conduit using a wire.

Hello, thanks for the reply! Unfortunately, the conduit is likely quite long, as it runs from the corner in the basement up to the first floor, ending at the junction box. I will try that approach anyway, but it’s probably about 5 to 6 meters (16 to 20 feet).

Any other ideas? Chiseling open and removing the junction box? 😱

Best regards

Vacuum from above using the upholstery nozzle while simultaneously loosening 2.5 m² (27 sq ft) of material with a wire rod.
If nothing else comes out, try to clear the blockage from above and below using a small electric drain snake.
Breaking open the surface can be a last resort.

You can simply borrow a cable puller; they are designed exactly for this purpose.
Copper wire with a cross-section of 2.5mm² (0.0039 inches²) may seem sturdy at first, but that’s both misleading and problematic. The tip is sharp-edged and can easily get stuck inside the conduit. It doesn’t follow the conduit well because it’s not flexible enough, yet it’s soft enough that eventually it can’t be pushed any further and just bunches up.

A drain cleaning spiral is also a bad idea because it can damage the conduit. In-wall conduit is made from thinner plastic, not from HT or KG pipes. Also, conduit tubing is not smooth but ribbed, which makes it easy for the spiral to snag and then cause serious damage. That’s what drain cleaning spirals are meant for—they’re designed to grind down hard deposits inside pipes. Depending on the type of brick in your wall, you might end up crumbling that, too.

That’s why you should get or borrow a cable puller. Nothing else will work.

MachsSelbst schrieb:

That’s why you should get a cable snake or borrow one. Nothing else will work.

Good points; honestly, I wasn’t aware of that before. I’ll do it and report back here, unless the vacuum cleaner method works first!

Thanks and best regards
Dennis