Unblocking SWA conduit

[DIY_Doctor]

Does anyone have any ideas about unblocking a conduit thats blocked with some concrete?

I have a 150cm twin-walled PVC conduit under porcelain slabs with a SWA cable running through it that has been clogged up with concrete near one end when the patio was being laid. I could do with passing another cable through the same conduit, so does anyone know any tips for unblocking the conduit? One end is open so I can get the cable about 95% of the way through before it hits a roadblock.

Cola to dissolve the concrete? Some other substance that would at least soften it, but wouldn't damage the conduit or the SWA sheathing?

 

[flameport]

Brick acid may dissolve some of it, certainly the cement part.

Bostik Concentrated Mortar & Brick Cleaner 5L | Toolstation

Hydrochloric acid-based cleaner for trade use only. Removes heavy cement and mortar stains from brick, concrete, paving, scaffolding and tools. For exterior use.

www.toolstation.com

however be warned, this is a dangerous product as it's basically just a bottle of hydrochloric acid.
It won't damage the plastic cable covering, but most certainly will attack any metal.

 

[oldbutnotdead]

150cm duct? Send the kids down
150mm is probably more realistic.
If you have any slack in the existing cable try pulling that to and fro.
Is it a straight shove through the duct to the blockage- if yes you could have a careful go with a scaff pole but there's always the risk of damaging the SWA.

 

[DIY_Doctor]

Sorry I meant 150cm length! Its about an inch diameter.

Unfortunately isn't straight as it goes under one part of the patio and comes up the other.

Been thinking about the Bostik stuff. Just wasn't sure if it would damage the SWA. I guess if the cable is covered then there shouldn't be any metal exposed?

 

[oldbutnotdead]

Ah ok. Try waggling the existing. Then try a cable fish (think machine mart sell them). Hope you're not planning anything too chunky extra cable wise, there won't be much of a gap. Also hope you still have the draw wire in, pushing cable through is so boring

 

[DIY_Doctor]

Its just an armoured CAT6e cable that I wanted to push through. Will fishing cable find its own hole to go through (if there is one)? And something like this will do?

 

[oldbutnotdead]

The machine mart one I bought years ago is metal so you can get a bit more grr behind it. It's flat and quite stiff. Similar to this Fish tape.
Or this one

 

[conny]

If the concrete infill is just near the end, you may be able to chip away at it with a small chisel/screwdriver. Break small bits off at a time and vacuum them away. After a while you may be able to see how far back it goes and then try some form of hook to pull it away.

 

[oldbutnotdead]

If the concrete infill is just near the end, you may be able to chip away at it with a small chisel/screwdriver. Break small bits off at a time and vacuum them away. After a while you may be able to see how far back it goes and then try some form of hook to pull it away.

Mmm, hadn't thought of that- yes if the blockage is at/near the surface and visible that'll be a much easier way to attack it.

 

[Sureitsoff?]

If you can see the blockage, could you simply drill a hole through it?

 

[Taylortwocities]

SWA doesnt need to be inside conduit.
Any chance you can jiggle a space under the slabs, maybe alongside the twin-wall conduit?

 

[DIY_Doctor]

SWA doesn't need a conduit correct, but I laid the conduit when the patio was being put in place knowing I'd need to run a SWA through it to power the outbuilding in the garden. Also useful if I ever needed to replace the cable as I won't be able to lift a porcelain patio - shame my patio guys were so careless.

Im dealing with something akin to this, except the patio is above the conduit, which comes up in the gravel border between the patio and a brick wall. The blockage is about 6 inches past the 90 degree bend. SWA is already in the conduit, but I now thought to run an ethernet cable in the same conduit.

 

[Sureitsoff?]

looks like that conduit would just pull out of that trench, and make it easier to find and clear the blockage. as has been said swa doesnt need conduit anyway and if you are going to put in armoured cat 5 that doesnt need conduit either

 

[JohnW2]

looks like that conduit would just pull out of that trench, and make it easier to find and clear the blockage ...

That would be true for whoever is the own of that patio in the photo of, but, if I understand correctly, as for the OP's situation ...

o<picture>
Im dealing with something akin to this, except the patio is above the conduit ...

Kind Regards, John