FTTP internal fibre size

Openreach have been doing lots of work around my area (weekends, late at night), installing their FTTP infrastructure and appear to now have some light on it as they were around checking light levels today.

There is an 8-way Optisheath Multiport in the pavement chamber that's about 3ft from my front path. I'm on a new (well, newish) estate so have tube from the pavement chamber to my front wall.

I'm trying to understand the installation process as my current copper NTE is just inside the front door and isn't an ideal location for the ONT (there's no power there for starters).

I'd like to have the ONT in my "computer room" which is upstairs. I've run some fibre tube from the master socket to the computer room (2 x 3.5mm tubes) but am trying to find out whether this is big enough for the fibre to fit through - if not, I can replace it but would prefer to do that sooner rather than later so it's all in place for the installation

This leaves me with the following questions:

Do Openreach still have an external splice point?

What's the diameter of the internal fibre?

If anyone knows the answers it would be greatly appreciated. I've made some enquiries with some Openreach colleagues who I deal with through work. If they come up trumps then I'll post the answers here, however they're mostly dealing with leased lines so don't have knowledge of the FTTP kit.

Many thanks,


Neil.

External splice point is preferred choice these days.

The fibre ran from inside to the outside has two diameters

white indoor part measures at 3mm diameter
with black outer sheath 5mm diameter

3.5mm tube seems far too small, if it was a piece of blown fibre which is much thinner then would be fine, but connectorised stuff is designed to cope with some push/pull so has tougher outer.

That's great information Andrew. Many thanks. Good job I checked!

I know that the fibre tails that Openreach use for leased lines fit through it (which would be 3mm) but if it's with the outer sheath then I'll have to sort out something else for it to run through.

I'm able to get some Copex but thought that may be a little tricky to pull it through!

Thanks once again.

https://www.openreach.com/content/dam/openreach/open...

Goes through what is expected in new builds.

whatever you put in put a draw rope in as well. i used 20mm flexi conduit

The internal fibre is usually about the same size as internal 2 or 3 pair copper cable. Your 2 x 3.5 tube sounds like what is used for blown fibre in commercial buildings for leased lines, etc.

If you’ve managed to get the fibre tube in place you could probably also get some 20mm flexible electrical conduit in its place (Screwfix sell it). I’d get a strong nylon cord threaded through it so it makes it easy for the engineer to pull the fibre cable through it on the day.

It seems most installs are now using an external CSP again.

Many thanks. I'll have a good read of that. I've had a quick flick through it already.

Thanks for the advice. I can use the tube that I've installed (I couldn't possibly confirm nor deny that it's blown fibre tube) to pull anything else through!

The tightest bit will be where it heads upstairs - there's a small gap beneath the plasterboard, between the floor boards and wall - that may take a bit of work to get a bigger tube through!

Many thanks once again.

Pulling a 3mm cable through a 3.5mm tube (assuming that's the inner diameter!) is an extreme ask. That's unless you're talking about blown fibre, and even then it's not just any old tube you need.

I provided 20mm round pipe, and that made for an easy install. I think you should be safe enough with 16x10mm (outside dimensions) oval electrical duct, which is cheap, low profile, and can be chased into plaster if needed: e.g. https://www.tlc-direct.co.uk/Products/MTOV16.html

Make sure you have a draw string in it in advance, and keep any bends as gentle as possible (no right-angled connectors).

Good luck with the installation!

Edited by candlerb (Tue 29-Sep-20 17:09:36)

I think you can also get 16mm flexible conduit but you’d need to check how easy that would be to pull through.

Is your tube black (with yellow stripe, for external duct use) or white? Think the designation for the white internal tube is ‘CW1803’, would be printed along it. The black stuff is also extremely stiff!