Electrical conduit blocked - Page 1
Forum section: electronics / beginners

author: tszaboo
author_rank: Super Contributor
timestamp: October 11, 2020, 09:33:18 pm
content: Hi. I was doing some work on the house. I was going to replace the old telephone line with Cat6. So I did what any electrician does, taped the two cable together, and started pulling on the old cable. It went well, up to the ~90% of the way, when the telephone cable just snapped. I started investigating, so the conduit is filled with concrete. The conduit is poured in concrete, and somehow it is very much filled up just below the surface. The blockade starts at around 50mm below the surface, and I have no way of telling where does it end.Otherwise the conduit is smooth, I have no trouble whatsoever pushing that CAT6 cable through up to the point where the blockade starts.So any tips? I dont think I can chisel it out, it is at an awkward angle, close to the wall, angled the opposite direction of the wall. How did concrete get there is beyond me, or how they pulled the phone line through in the first place.

author: piku
author_rank: Contributor
timestamp: October 11, 2020, 09:43:25 pm
content: How can you tell there is concrete in the conduit. Can you see it? If so, perhaps a long masonry drill bit to break it up.

author: TimFox
author_rank: Super Contributor
timestamp: October 11, 2020, 09:44:15 pm
content: My guess is that the concrete leaked into the piping after the original phone line was pulled.We used to have that problem with radiation-shielded concrete cells, where all the wires had to go through conduits in the floor between the equipment and the operators' room, and the contractors were sloppy with the concrete pours.

author: tszaboo
author_rank: Super Contributor
timestamp: October 11, 2020, 10:06:40 pm
content: Quote from: piku on October 11, 2020, 09:43:25 pmI used a borescope. And I can reach it with a wire, it makes scratch-y noises like concrete.I cannot fit a drill at that angle. The drill would be where the wall is.The conduit goes into the floor, not the wall. It's below the distribution box, utility closet. I have water pipes and 230V in the way.Quote from: TimFox on October 11, 2020, 09:44:15 pmYou mean they pulled the wire in before pouring the concrete? That would make sense. Today that is probably a building code violation, but 30 years ago when the house was built probably not.What pisses me off, I had electricians redo the wiring in the house last year. It didnt have earthing upstairs, and the distribution box was with melting fuses. And I dont remember them swearing that any of the conduits were fubar. Then I try finishing the job and I run into this.

author: rhodges
author_rank: Frequent Contributor
timestamp: October 11, 2020, 10:11:12 pm
content: Maybe break up the concrete with acid? Push a tube in the conduit so the tube touches the concrete, then pour acid in the tube?Hydrochloric acid may be fastest, but it will also attack the zinc on the conduit. Maybe acetic (vinegar) or phosphoric acid?

author: tszaboo
author_rank: Super Contributor
timestamp: October 11, 2020, 10:20:18 pm
content: Quote from: rhodges on October 11, 2020, 10:11:12 pmThe conduit is plastic, I'm guessing it is PVC, though it is not written on it. At least not on the part that sticks out from the floor.

author: andy3055
author_rank: Super Contributor
timestamp: October 12, 2020, 02:27:08 am
content: Try a flexible impact bit holder like this and use a masonry drill bit.https://www.amazon.com/Makita-B-51873-Flexible-Impact-Holder/dp/B01FHTWKPQ

author: Zeyneb
author_rank: Regular Contributor
timestamp: October 12, 2020, 06:49:36 pm
content: Hi,There might be a situation where a electrician or more likely a builder did a bad job. So, for example a previous owner asked some contractor to create some electrical socket at a desired location. They simply put a angle grinder in the wall and made a cut. Then they realize they cut through some other wire (like telephone) that crossed the one where the cut was made. Then instead of cutting deeper to have each wire in their own PVC pipe they improvise by not having PVC there and crossing both wires in bare stone/concrete or whatever the wall is made of. That was the case in my apartment. I know because I decided to kick of the ordeal of fixing it myself with putting an angle grinder in the wall. It is unimaginable the amount of dust this create.So if you have a "stalen trekveer" (dutch), which is flexible you might be able to probe around to get an idea what might be hidden below your floor or inside your walls. Maybe you would be able to do this from both ends.There is also a dutch forum called klusidee.www.klusidee.nl. People there do usually know about dutch regulations like NEN 1010 and maybe recognize things specific for your house if you're willing to share some photo's on that forum.

author: tszaboo
author_rank: Super Contributor
timestamp: October 12, 2020, 09:47:14 pm
content: Quote from: Zeyneb on October 12, 2020, 06:49:36 pmI think what happened is this: originally there were tiles near the entrance. The previous owner layed (quite nice) wooden floor. The tiles were removed from the electrical cabinet, and they poured concrete in it's place to make it even. There is concrete over the MDF panel at the back and heat isolation. It is a shoddy job.stalen trekveer is called fish tape. I dont have one unfortunately, but I have a borescope, so I can see the concrete. Its in the bend of the PVC pipe, probably it was bent too steep. I cannot push dont the camera more, the hole is too small. A fish tape wouldn't fit, nor the ethernet cable.Thank you for the advice, unfortunately my dutch is not that good yet...

author: Zeyneb
author_rank: Regular Contributor
timestamp: October 12, 2020, 10:54:13 pm
content: Alright, I wish you luck with any attempt of fixing it somehow. Or maybe you find some different route to get ethernet where you want it.Stuff like this would really bother me and I will always look for a fundamental solution.andbut I'm not that stupid to use my head, a chisel would be a better tool for that.