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[NewtronStar]

Worth clarifying perhaps that neither  Cat 5 nor 5e are normally shielded or screened.

Screened/shielded versions are available however and I agree that these versions would not be best for this application.

Les's link mentions a cable diameter of 4mm, which I suspect rules out the possibility of screened or shielded.   Moreover, I feel sure, Les would have mentioned if it was.

I can say my old entension cable 2 pair cable has a diameter of 2mm and the cable from BT80 to NTE5 has a diameter of 4mm and thats CW1308 2 pair.

http://www.elandcables.com/documents/CW1308%20Cables.pdf

[sevenlayermuddle]

Useful data from a Beatie subsidiary, here...

https://www.btcables.com/our-products/data/

It was recently suggested in another thread that CW1308 is actually Cat 3.  I have no reason to doubt that supposition, so let's take it to be the case.

Now, according to that BT cabling data, Cat 3 is specified for data rates of 16Mbps.  Fine for ADSL1, even for ADSL2, but you can see why BT might want to discourage its use for VDSL, Cat 5 being the first that is specified for Infinity Data rates. 

According to the BT link, Cat 3 and 5 both have the same characteristic impedance, so no major problems there.  The main difference, as far as I know, is twist rate - which is probably what BT are referring to when they say

It provides much improved shielding from interference, helping you get the fastest broadband speed possible for your line.

Of course, using Cat 5e for extension wiring doesn't undo the damage of having Cat 3 from the cabinet.  But two wrongs do not make a right, so I can see why they'd want to encourage Cat 5/5e for any new wiring.  Especially in the end-users premisses where, arguably, most of the interference will be encountered.

[Dray]

I don't think digital data rates apply to analogue phone signals.

[sevenlayermuddle]

Post deleted.   

[burakkucat]

Useful data from a Beatie subsidiary, here...

https://www.btcables.com/our-products/data/

Interesting.    Thanks for the link 7LM.

[Dray]

Ah yes, I see CAT3 is rated up to 16MHz which makes it unsuitable for VDSL2 running at 17MHz. CAT5 is rated at 100MHz.

[sevenlayermuddle]

Ah yes, I see CAT3 is rated up to 16MHz which makes it unsuitable for VDSL2 running at 17MHz. CAT5 is rated at 100MHz.

I believe the association between analogue bandwidth and achievable data rates is a complex equation, predicted by

http://en.m.wikipedia.org/wiki/Shannon–Hartley_theorem

As said, it is complex.   Time was (circa early 70s) I could get my head around that stuff, these days I find it tough.

But in essence, just because a cable can carry a signal at 16MHz, or at 8MHz, one cannot assume that it will carry the two signals together at the same time.

[NewtronStar]

In that case i'll send back the CW1308 cable as not fit for purpose on any VDSL2 line and look for CAT5e 2 pair unshielded.

[sevenlayermuddle]

In that case i'll send back the CW1308 cable as not fit for purpose on any VDSL2 line and look for CAT5e 2 pair unshielded.

You can if you want, but perhaps don't cite this forum as supporting evidence - I don't think anybody intended to give that impression, least of all me.

[NewtronStar]

In that case i'll send back the CW1308 cable as not fit for purpose on any VDSL2 line and look for CAT5e 2 pair unshielded.

You can if you want, but perhaps don't cite this forum as supporting evidence - I don't think anybody intended to give that impression, least of all me.

No worrys I only intend to do this cabling DIY job once as it will require me to go up into the loft and pull back 20 inches of loft insulation and track the cable down to NTE5 and DATA socket.
So it's better me knowing the right cable for this job than find out later it was the wrong type.

[sevenlayermuddle]

You'll also struggle to find a supply of two pair Cat 5e, other than that BT extension kit, if it really is Cat 5e...

As you'll see in a different thread, I abandoned plans to extend by about 20metres using Cat 5 as the degradation was more than I could bear.   That did employ three different cable sections, linked by RJ11/45 connections, a single contiguous cable may be better but I wouldn't bank on it.

[les-70]

  The "Genuine BT Openreach Engineer's ADSL/VDSL extension kit" cable has no markings on it at all.  Its is 5mm outside diameter.

 Re the above discussion as far as I know all the cable from the Cabinet to the master socket will be CW1308, if so VDSL does go down it albeit with the usual attenuation.

[sevenlayermuddle]

  The "Genuine BT Openreach Engineer's ADSL/VDSL extension kit" cable has no markings on it at all.  Its is 5mm outside diameter.

Like yourself then I would be strongly tempted to think it is CW1308, despite being described as Cat 5e, and regardless of theoretical benefits of Cat 5.

One more think for NS to consider... if you're going to a lot of bother then using fully loaded (4 pair) cat 5 would leave you with the alternative option of pressing it into service as an ethernet at a later date, if that option has any value?

[burakkucat]

http://en.m.wikipedia.org/wiki/Shannon–Hartley_theorem

As the above link appears to be broken here is a complete, intact link. 

[JGO]

But in essence, just because a cable can carry a signal at 16MHz, or at 8MHz, one cannot assume that it will carry the two signals together at the same time.

AIUI xDSL divides the data stream into many independent tones, 4.3125 kHz wide, so that variation in cable delay between channels simply means there is an extra delay for the slower channels catch up before the data in all tones can be combined into a many bit word.   It isn't a wideband single channel signal, which would certainly be ruined by delay variation. 
If Ethernet is such a fast single digital channel, then cable which is OK for xDSL can be useless !