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How long is the internal cable for full fibre? (installation options)

boonjj — Sat, 29 Mar 2025 11:39:52 GMT

Hi, I'm getting fibre installed and I have a question about the length of the internal cable and how close things need to be. I have included a picture to make the visual easier.

So: I would like to have the external box placed besiden my front door, on the front wall of my house (9 inch thick wall). Then I would like the internal box on the opposite side of this front wall. Then I would like the cabling run either 7 metres or 4 metres (depending on whether the box is installed at ground level or not, as if it is then the cable will be need to ran up and down the inside door) to reach the near double power socket.

Is this a viable set-up? I don't know how long the internal cable can be ran. Is having it run for 7 metres total around a door viable? Is having the nearest power socket be 7 metres inside the house okay?

Thanks for your help.

Re: How long is the internal cable for full fibre? (installation options)

licquorice — Sat, 29 Mar 2025 11:51:23 GMT

Your question doesn't make sense. The 'internal box' as you call it is the ONT which requires power. Not sure what cable you are talking about.

Re: How long is the internal cable for full fibre? (installation options)

imjolly — Sat, 29 Mar 2025 12:17:43 GMT

if the 'internal box' the ONT is placed as in diagram then you are going to have to run a power cable from the ONT to power outlet the cable that comes with ONT will not reach

you are going to need to discuss siting of ONT with installer

Re: How long is the internal cable for full fibre? (installation options)

boonjj — Sat, 29 Mar 2025 12:35:34 GMT

@imjolly

I only placed the ONT there because I thought I read that the External and Internal box will be placed on the opposite side of the same wall.

If that is not the case, then the external box can remain where it is, and the cable will be run to the power socket and ONT which will now be beside each other. (if you look at the picture, just move the internal box to now be beside the power socket)

Does that set-up sound viable?

Re: How long is the internal cable for full fibre? (installation options)

licquorice — Sat, 29 Mar 2025 12:53:09 GMT

As said, you will need to discuss it with the installer.

Re: How long is the internal cable for full fibre? (installation options)

36ULW — Sat, 29 Mar 2025 17:53:33 GMT

Openreach use what’s called an Inside-Out Cable. They come in pre cut lengths of 5, 10, 20, 30 and 50m.

The outer sheathing can be striped back where it goes from the outside to inside.

When I did FTTP Installs there were two Installs Types, Basic and Premium.

On a Basic the Engineer can run up to 10m Internally and on a Premium 50m.

That was a few years ago though, rules may have changed since.

Re: How long is the internal cable for full fibre? (installation options)

pddco — Mon, 31 Mar 2025 07:36:12 GMT

@boonjj If you’re like me I try to think about options before being put on the spot when the installer arrives. Trouble is, unless you’re an installer you don’t really know what’s possible. All you have to go on is that the internal ONT has to be powered, connected by fibre to external box and connected with an Ethernet cable to the hub. It has a I think about a 1m power lead. The cable from the External box (Customer Service - or is it Splicing? Point) CSP to the ONT is a a thin fibre cable. Which - from others here comes in various lengths. But before the installer arrives you don’t really know how far they would be prepared to run it. Anyway, something to think about - fibre cable doesn’t like sharp bands. So going round a door frame with sharp 90 degree bends, like you do with copper, is not possible. The minimum bend radius from what I gathered on this forum is that of a £2 coin. So wouldn’t look very neat around a door.
Of course the BT hub has to be connected to the ONT with an Ethernet cable. Now being copper you can be far more flexible how and where the cable runs. And in practice can be any length from ONT to hub ( well in theory upto 100m but we’re talking a house situation here). The downside to the Ethernet is that the Installer is unlikely to play ball and you’d have to provide and route the cable yourself. Saying that, at least you could put a temporary cable in place ( a long Ethernet patch lead or whatever) just so the install gets done. And then get someone in to make a neater more permanent job?

Could the External box (CSP) be put somewhere else that would make your internal route / setup easier? But at the same time still be straightforward ( least time/ trouble/ cost) for the OR external works?

Re: How long is the internal cable for full fibre? (installation options)

iniltous — Mon, 31 Mar 2025 08:46:42 GMT

No doubt there will be many thousands of FTTP installations every week , maybe thousands per day , and the vast majority are completed without any drama , there obviously will be some customers who are somewhat ‘precious’ about where the CSP is sited , not happy about surface wiring and have unrealistic expectations around a domestic installation entails as far as amount of cabling , unsuitable or ‘unsafe’ locations for the ONT etc .( an installation that is usually a ‘free’ to the customer ….think of it as expecting a £10 ‘car wash’ to be the same standard as a £500 car detailing ) but most are satisfied and the customer and engineer both agree to the way the installation is completed.

The customer has the final say , if you can’t agree the way the installation can be done in conjunction with the engineer , simply refuse …..the order is cancelled and everybody moves on .

Re: How long is the internal cable for full fibre? (installation options)

GarethPrice — Mon, 31 Mar 2025 11:00:28 GMT

@boonjj Worth bearing in mind that the ONT doesn’t have to be plugged directly into the power socket, but can run off a power extension block., which might be easier to route the cable alongside the bottom sill of the door, and if covered, would be more resilient than having the internal ONT cable routed that way

Re: How long is the internal cable for full fibre? (installation options)

chrisjp — Mon, 31 Mar 2025 13:34:40 GMT

"The customer has the final say , if you can’t agree the way the installation can be done in conjunction with the engineer , simply refuse …..the order is cancelled and everybody moves on."

The trouble with that scenario is that BT will very likely go ahead and shut down your previous FTTC service anyway, because they'll assume that the FTTP installation has gone ahead. Communication between BT and Openreach is very patchy.
So, if you refuse the FTTP installation, you have a quite high risk of being without any broadband service at all, and facing a mammoth telephone session with BT trying to get it re-instated.

Re: How long is the internal cable for full fibre? (installation options)

david39ni — Mon, 31 Mar 2025 15:53:59 GMT

BT Was really accommodating to me as to where I wanted the hole inserted in the wall if u make them a cupa its amazing what gets done lol

Re: How long is the internal cable for full fibre? (installation options)

iniltous — Mon, 31 Mar 2025 16:50:00 GMT

Things can go wrong , but if the FTTP installation is not completed (and eventually cancelled) that should leave any existing copper pair service unaffected, is it possible that the existing service is unwitting ceased in thus situation , it happens, but as with most things , a few examples on forums like this are not indicative of a general failure, the majority will have their existing service unaffected by cancellation of the FTTP order .

Re: How long is the internal cable for full fibre? (installation options)

boonjj — Thu, 03 Apr 2025 17:57:27 GMT

Quick update: Installation all went well. No hassle about the length of the cable. The cable from the External box went up, around, and down the inside doorframe and then fitted into the ONT beside the power socket. So that was all fine.

The only issue I had was that the man said it would take 30 minutes for the internet to get up and running but it ended up taking about 2 hours. I got emails and texts after 30 minutes saying the internet was up so it was supposed to be going, but it wasn't working despite me trying to reset the router and turning on FTTP in the router settings etc. The router just stayed on a solid orange light. What seemed to ultimately fix it was just turning off the ONT at the plug and turning it back on. All has been well since.

Thanks for the help everybody.

@36ULW Thanks for info. I did do some digging and found some information about the length of the cables they use and how they apparently have 10/30/50 metre cables and there is a Premium price where you can pay to get longer cables or something (I needed a sub 10 metre cable so maybe that helped me not run into any issues). The only thing I'd say is I don't know why this info isn't included in the information they sent me in the emails - they directed me to BT website but those webpages had very basic information about the installation and I had to dig around myself to find information about the cables.

Re: How long is the internal cable for full fibre? (installation options)

pddco — Thu, 03 Apr 2025 18:42:13 GMT

@boonjj The fibre cable went up and around the door frame. Just wondered how it looked. Is the white inner so thin you don’t really notice it in practice? Also, is a cover or something put over the hole on the inside where the internal fibre cable comes in from the external box ( CSP)?

Re: How long is the internal cable for full fibre? (installation options)

boonjj — Thu, 03 Apr 2025 18:52:33 GMT

@pddcoIn practice I don't notice it, no. But it probably helps that I have a white door frame for it to blend in with. If you have different a different background, say black, it would probably stand out.

Another very minor thing is that the wire is not flush with my waist height skirting, so it sticks out a tiny bit there at that junction. Not sure if that can be installed better or if the cable just shouldn't be bent that much. But it's a small thing, I'm not bothered about it.

There is no covering on the hole of the inside of wall, no. The hole is bit bigger than the wire, you can definitely tell if you look at it. But I'm never looking. It's actually covered by the bottom of front door curtains anyway.