2.5km line

Does anyone have actual experience of a 2.5km line? What speeds are actually achieved?

About to do an upgrade on a friends line - currently around 1Mb ADSL with around 9km to the exchange - which suggests reasonable quality .

The cabinet is 2.5km and the fibre cabinet right next to it. Estimates are: 7.9 to 4.5 Clean and 5.9 to 3 Impacted. So, I am wondering how realistic those actually are especially as most of the run is overhead and on shared power/BT poles.

No actual experience to add, but...

IIRC, the model that BT uses for the access network means that no line is longer than 6.5km of cable equivalent to 0.5mm copper.

What this means in reality is that the resistance of the cable actually used must be no higher than the resistance of 6.5km of 0.5mm copper (1km of a pair would be 180 ohms). The same stands for attenuation values.

If a cable is actually physically longer than that, then it must be formed of thicker copper, at least partially.

IIRC correctly again, 0.7mm copper is half the resistance of 0.5mm copper, while 0.9mm copper is around one third.

We know the total line length here is 9km, so some of it must be thick ... but which bit? Somewhere in the D-side or the E-side?

That means there is most certainly a chance that the estimate is plausible, but the issue with thickness is that almost no-one knows it - so you cannot make any reasonable comparisons with other 2.5km lines.

I'm pretty sure the only way to find out is to order it...

I would have thought the E side would be fibre.

Exactly ... that is why I said "reasonable quality".

I also know several hundred metres were replaced recently - cable theft! on the E-side.


The real pain, is that the house is around 1km straight line, and under 2km by road from the exchange!

In reply to a post by BatBoy:

I would have thought the E side would be fibre.

Not yet! He is talking about the current line and gauge of copper in use in the various parts.

I would imagine that heavier poundage cables are towards the end of a run on local main cables. Duct space at the exchange is at a premium.

I doubt you would find a 0.7mm cable anywhere in the UK.

The only thing leaving the exchange at 0.9mm is likely to be a junction which may drop off and feed punters in remote areas but is highly likely to have loading pots on.

Edited by deleted (Mon 01-Dec-14 21:36:43)

Some time in January I might be able to order FTTC on my mum's line which is 2.57KM from the cabinet by road so could easily be 3KM long! Really doesn't sound promising for FTTC

So I'm very interested to hear what your experience is like.

Shame her property doesn't connect to the same cabinet as all other properties in the post code, which is just 800 meters in the other direction.

I'll likely try and order a BT line for the field next to the BT pole that delivers the overhead line to the neighbours that connect to the nearer cabinet and then run Ethernet back to the house ~85 meters away. Might be an opportunity to connect other neighbours via a little wireless network also...

I live in a tiny village in rural Suffolk. According to the BT Openreach engineer, I am 2.9km from the cabinet (which is in the next village) with a 'near perfect line' (engineer's own words)

I have had Fibre installed for just over 3 weeks and I've gone from 1.9Mbps down 0.25 up on DSL to 2.9Mbps down 0.6up on FTTC... not much of an improvement... my ping is around 30-40ms

When the engineer came out following my complaint to ISP (I use Timico and have done for many years as they always gave me the best speed locally) he was unable to even get his test kit to sync although my modem connects pretty quickly)

My next door neighbour just had FTTC installed yesterday. He is less than 100m closer to the cabinet. He used to get 0.9 down and 0.4 up (suggesting that his line was not as good as mine?) but he is now getting 7Mbps down and 0.4up with a ping of about 75ms.

I thought that the line speed would drop off in a near linear manner at this sort of range so I have a couple of questions...

1. Is it possible that the bit of line that comes after his house has a problem (although the BT engineer seemed to think not)?
2. He is with BT - is it possible that BT prioritises speed for their own customers?

Any thoughts would be welcome.

Even 2.9Mbps is faster than almost everyone else in the village but as I'm paying for a service which promised 4.5 - 8Mbps it would be good to get it!

This is what I was hoping to hear - that people are getting service at over 2.5km - albeit with variable speeds and that the higher clean figures are attainable.

In reply to a post by RuralFibre14:

I thought that the line speed would drop off in a near linear manner at this sort of range so I have a couple of questions...

1. Is it possible that the bit of line that comes after his house has a problem (although the BT engineer seemed to think not)?
2. He is with BT - is it possible that BT prioritises speed for their own customers?

What you might be finding is that a large number of tones or bins are using just one or two bits rather than the maximum so any small change in noise or attenuation of those could result in the loss of the remaining ones and what looks to be a disproportionate effect.

The latency figures do suggest he has a greater level of interleaving on.

You could have localised noise in your house, or the modem has slightly different termination characteristics resulting which can effect the sync speed - even on a good line.

And NO, BT would not be prioritising speed for their own customers.

Make sure your modem is located at the master socket and there is a minimal amount of electrical or electronic equipment close by. Does the cable enter the house and immediately terminated in teh master or is there a large amount of internal wiring?

Promised? Or estimated? If it was a promise then feel free to complain but given broadband is not a guaranteed service their remedy may be a choice of cancelling and just going back to ADSL. The 2 Mbps USC seems to be being met which is a big tick for the politicians involved.

Beyond 1.5km the variables around individuals situations are such that you cannot accurately predict the speed and the drop off is a long way from linear.