Which type of conduit to place in wet concrete?

[OBone]

I need to rerun an internal telephone cable in flexible conduit that will be set into a concrete floor which will be laid soon. Looking at the screwfix website there are two types.

20 and 25mm. Crush-resistant, self-extinguishing, LSF / Zero Halogen Polpropylene. Rated IP55. Use with 'Industrial' and 'Metal Clad' ranges. EN 50086 BS 4607.

and

20mm. Crush-resistant, PVC-coated Galvanised Steel Conduit and 10 nickel plated brass locknuts. Rated IP55. BS 50086.

Do I need to use the PVC coated Galvanised Steel version or can I use the cheaper version?

thanks

[Dave Liquorice]

IMHO you'd only *need* the steel version if mains was involved and it was going to be buried less than 50mm below the floor surface.

On the basis that there is no mains involved and steel will rust (even galvanised eventually) I'd use the plastic. Note it can be "fun" pulling cables through plastic corrogated conduit unless the run is dead straight, don't forget the bends at each end to bring the duct above the floor and always fit the biggest size you can. More space makes it a bit easier to add cables later and most of the "cost" (labour, time, ease) is putting the conduit in not materials.

[.]

do you /need/ to rerun the cable ? can't you use DECT ?

if not, plastic is ok but as you've been advised already, put the cable in the conduit before setting it in the concrete.

[OBone]

Thanks for the replies. I have to run a cable as it will be used for broadband. I will also place the cable in the conduit before laying it in place.

[meow2222]

Both are a bit OTT for phone wire. Steel is liable to cause concrete faliure through rusting at some pont, so I'd say no to that one.

Why do you need to conduit the stuff at all?

I dont know where the wire is going from and to, but when burying LV wiring I'd always consider putting in a good deal more cores than wanted immediately, as the cost is close to zero and the possible future uses many.

NT

[.]

cables ? what are these cables of which you speak ?

go wi-fi ;-)

[Harry Bloomfield]

OBone wrote on 30/12/2006 :

Ordinary plastic conduit will be more than adequate for the job and cheaper/easier to use - no need for steel at all.

[Dave Liquorice]

Cables? Reliable, secure, faster...

[Andy Wade]

It might be more practical to put in a draw-string (use polypropylene twine) and temporarily plug the ends of the tube to prevent concrete entering. Then pull your cable through later, when the site conditions are more amenable to delicate operations.

[gort]

Leave a lenght of cord in the conduit as well because there WILL come a time when you need to pull another cable through.

Dave

[.]

yah, I can see you know a /lot/ about it.

[Phil L]

Don't pay ridiculous prices for plastic tube, get overflow pipe from B&Q, it's bendable too, so you don't need as many elbows

[meow2222]

Mechanical protection is not needed, the concrete will be prettty good for that already. A plastic pipe sure wont add any strength. Why is the cable ok to clip to the wall, yet when buried in concrete you want conduit?

NT

[OBone]

To answer points raised in some of your replies the cable will be a CAT 5 internal computer cable that will be used to push the incoming feed to my computer room. Three pairs will be used. One pair will be used for the main line, which will be terminated on a master line jack with a built in filter. Pair 2 will push the line back to where it started to connect up with the rest of the existing house wiring. Pair 3 will be used for a second business line leaving pair 4 spare. I already have this arrangement up and running but the wiring runs across a porch that is about to be built so I need to bury the cable.

The reason for not laying the cable direct in concrete is that I have a fear that over the years the concrete could have a detrimental affect on the cable and as the underground bit will be only around 4ft until it enters the garage I prefer to play safe and run it in conduit.

Many thanks everyone for your input.

[Dave Liquorice]

Are there any WiFi systems that'll run at 100Mbps throughput? Are there any WiFi systems that have physical only access? Are there any WiFi systems that "just work"?

[.]

yes. though quite why anyone would resort to a slow network when the modern equivalent of floppynet is much faster and far more secure.

don't be silly, if the "hax0r" wants it enough they will simply steal the box.

yes. all the ones I set up do.

now I /really/ know how much you know, ta ;-)

[Geronimo W. Christ Esq]

Wireless routers are cheap ?

[Geronimo W. Christ Esq]

There are, but this hasn't been standardized yet. They run at 108Mbps.

However, given that the broadband connection under ideal conditions will run at 8Mbps max (24Mbps max w/ADSL2/+) what's the point in having a LAN which is faster ? Pretty silly idea. Even then, in an office LAN I've seldom seen a serious need for high bandwidth.

I'm not sure what this requirement means.

Mine did, right out of the box.

[Geronimo W. Christ Esq]

Oh, you mean for managing it.

Yup, my router has a configuration setting so that it cannot be managed over the wireless connection.

[.]

shhhhh :-)