Oval conduit

[Stephen H]

I'm doing first fix in a house that has plasterboards on thermalite blocks. I would like to use oval conduit between the TV/Satellite/Radio/Telephone/Network wall points up to the loft. This conduit would go in between the plasterboard and thermalite blocks. I will cut out access holes in the plasterboard to clear battens/noggins/dot'n'Dab patches etc, I have access to upstairs floorboards and loft.

I have already investigated

but I have two problems with it after buying a few pieces.

There are no end to end couplers available as they are only 2m long and also when pushing up between plasterboard and thermalite wall, its not sufficiently flexible enough, it is brittle and breaks when I bend it too far. This will be an issue if the socket is close to the floor and I'm pushing up towards the loft.

What I am trying to achieve is runs of continuous conduit from the pattress boxes in a straight run to the loft so I can use fish tape to thread the CT100, telephone and gigabit cabling through.

I want to use conduit so that if cable specs become updated for the next big thing, such as 10 gigabit or 100 gigabit cable or some successor to CT100 cable, I can then swap the cables out without upsetting SWMBO with damaged decor.

Any suggested ideas or products anyone?

Regards,

Stephen.

[Andrew Gabriel]

Sounds like it's gone a bit past first fix stage?

3m (or maybe longer) is available from electrical wholesalers. I certainly have lengths which are too long to stand up in a room. I think even B&Q have it longer than 2m (but they don't do all sizes).

I think your problem is the building is past first fix. If it's not far past it, it may be worth cutting out the plasterboard, putting in your straight conduit runs, and then having the plasterboard refitted or doing it yourself.

[ARWadsworth]

have never heard of the 3rd fix mentioned in this article.

Although most electricians I know, when rewiring a house would also refer to the removal of the plaster as part of the first fix. Assuming this is not a new house the term first fix would still apply.

[Brian Gaff]

How he gonna do that at this stage?

Brian

[NT]

Just one thing. When installing conduit, put your cat5, CT100 etc _outside_ of it. It might sound odd, but it results in greater cable capacity for a given amount of conduit. Cat5 etc will inevitably become outdated for computer uses, but it can always be used for other things then.

NT

[John Rumm]

investigated

I have two

You could actually extend that logic to any cable really. Twin & Earth etc is fine buried in plaster, so you could install empty conduit for future expansion capabilities.

[Terry Casey]

The oval conduit I've seen is quite small, so probably wouldn't support future cabling expansion anyway. In fact, I doubt you'd get the first three cables that you're planning through it unless, perhaps, you tape them together and run all of them in at the same time.

Find something stiff - your oval conduit, bamboo poles taped together, etc., to establish each run, then tie nylon rope to it and pull back through.

Now tie the rope to your cable AND another length of nylon rope and pull through to the outlet position. Repeat the process, using the nylon rope left in situ, to pull additional cables in the future.

Repeat until plasterboard/thermalite cavity is full

[Tim Watts]

20mm is a "medium" size in oval and will take 2 of almost any round cable (I have tried with aerial, Cat5e and phone cable). Aerial is a bit snug - you would not want any kinks or bits flattened by nails/clips. 20mm also drops through a 20mm knockout. However you can get bigger versions.

[Terry Casey]

But the OP wants future proofing built in. How do you expect to run new cables into your 'snugly' packed conduit?

As I said, it "probably wouldn't support future cabling expansion anyway". You seem to be reinforcing my point ...

[Tim Watts]

It is a little easier to feed 2 rounds in at once, but it is most certainly possible to pull a single down 2m of oval with a cable already in. For this I push a plastic "fish tape" up, tie the cabel to that and pull down.

Sometimes, if one or the other cable are small, eg phone wiring, the larger cable can snag - but it's usually fixable with a bit of back-pull and wiggling.

And of course you would lay 2 drops of oval to a single box ideally and 4 to a double so you'll generally have an empty one available (as making a chase is a PITA but making a 2-3" wider chase is hardly a lot of extra work unless you end up chiselling brick if the plaster is not thick enough).