PCP Wiring changes for FTTC/VDSL

I now have a very clear picture of what happens in terms of the local phone wiring, when going over to VDSL.

I noted a Kelly Technician opening up the existing, local PCP, where the Exchange Lines (E-Side) connect to the individual phone lines in each house, the D-side.

I spoke to him then watched as he carried out the operation for another house on the estate, describing each action as he did it.

He confirmed that there was no need to open the FTTC Cabinet - and that he was not authorised to do so.

His van contained what appeared to be a similar range of equipment, connectors etc as an OPENREACH van.

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In the PCP, he first identified the existing line and its E-to-D connections, by gel crimping (actually IDC) on extra wires to make temporary connection in to the existing circuit, ringing the Test Number 17070 to confirm that identification.

If I saw correctly, the D-side pair to the house were Blue and Yellow, whilst the E-side pair to the Exchange were Red and Black.

That existing E-D joint was at the left of the PCP, whilst the links to the FTTC were at the right, about 1 Metre apart.

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The "links" from the FTTC cabinet were in fact double links (4 wires), similarly coloured, ie Blue-Yellow and Red-Black.

He apparently checked that he had found the FTTC set/s powered up for the neighbour, unless all are.

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Using new wires, appropriately coloured, from reels, he extended those "FTTC" cabinet links (all 4 wires) over to the left side of the PCP, about 1 metre for each wire and using "gel crimps".

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He cut the four wires of the existing D-E Joint, far enough back to also remove his temporary links.

He then connected the existing D-side wires to the corresponding extension wires by colour; and similarly with the E-side pair.

Thus the interruption to the basic phone service was about 1 minute, out of about 10 minutes from Arrival to Departure.

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The working effect is to move the D-E joints from inside the PCP to inside the FTTC cabinet, thus extending the phone circuit by 2 times the link length, ie in this case by 2 times 50 Metres = 100 Metres; and with extra joints in each wire.

So my original Exchange copper distance is now 1,286 Metres (existing) + 2 times 50 Metres (new Double Link to pick up the VDSL at the FTTC Cabinet), coming to 1,386 Metres, whilst the D-Side has been effectively extended from 250 Metres originally to 350 Metres. (Edit ~ 300 Metres)

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The one thing that I could not establish is whether there is a VDSL HF Rejection Filter built in to the FTTC cabinet, to prevent that VDSL signal going back along the combined new short extension and old E-side to the Exchange.

Generally, I think there must be such a filter in the FTTC. Perhaps someone with direct knowledge of the FTTC Cabinets can clarify.

The overall arrangement appears to be to minimise the "on-site" work and avoid opening the FTTC Cabinet, with its DSLAMs, Mains Power Supplies, Back-up Batteries etc.

Edited by deleted (Sun 31-Aug-14 13:43:56)

I suspect there are plug in filters within the fttc cabinet that also act as connectors for the in- out pairs

No need to suspect all pictured on http://www.coolwebhome.co.uk/fibre-cornwall/ (really should go back again now I have a better camera)

"So my original Exchange copper distance is now 1,286 Metres (existing) + 2 times 50 Metres (new Double Link to pick up the VDSL at the FTTC Cabinet), coming to 1,386 Metres, whilst the D-Side has been effectively extended from 250 Metres originally to 350 Metre


Yep but as you pick up the VDSL at the DSLAM the 50M to it does not matter its only the 50M comming back that counts so effectively as far as BB goes your d side is now 300M.

Thanks, BTBert.

300 Metres was my intention; but ...

Afternoon Andrew

Can you or anyone else identify the major sectors and units in this photo?

In the PCP, he first identified the existing line and its E-to-D connections, by gel crimping (actually IDC) on extra wires to make temporary connection in to the existing circuit, ringing the Test Number 17070 to confirm that identification.

If I saw correctly, the D-side pair to the house were Blue and Yellow, whilst the E-side pair to the Exchange were Red and Black.

The blue yellow wire you saw was in fact probably a jumper wire.

That existing E-D joint was at the left of the PCP, whilst the links to the FTTC were at the right, about 1 Metre apart.

Unless the E side and D side pairs are on the same bunch, then there should be 2 existing E-D joints - one at either end of the piece of jumper wire which links them. They may or may not be on the left depending on which bunches the E side and D side pairs are on.

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The "links" from the FTTC cabinet were in fact double links (4 wires), similarly coloured, ie Blue-Yellow and Red-Black.

The "double links" you mention are the E side and D side pairs to the FTTC cabinet. The D side pair is basically an input for the dial tone. The E side pair then provides the dial tone and VDSL signal out.

Those colours you mentioned are not used. The blue-yellow is jumper wire, the red-black is not used for VDSL tie pairs so not sure what you saw.

Using new wires, appropriately coloured, from reels, he extended those "FTTC" cabinet links (all 4 wires) over to the left side of the PCP, about 1 metre for each wire and using "gel crimps".

-----------------------------

He cut the four wires of the existing D-E Joint, far enough back to also remove his temporary links.

He then connected the existing D-side wires to the corresponding extension wires by colour; and similarly with the E-side pair.

He has done that wrong and would get a critical defect for that if it was audited. He should have removed that jumper wire going to the copper D side and ran a new jumper from the FTTC E side to the copper D side. Instead he has been lazy and left it in place, then just connected another jumper wire to the end of the jumper wire.

Thus the interruption to the basic phone service was about 1 minute, out of about 10 minutes from Arrival to Departure.

--------------------------

The working effect is to move the D-E joints from inside the PCP to inside the FTTC cabinet, thus extending the phone circuit by 2 times the link length, ie in this case by 2 times 50 Metres = 100 Metres; and with extra joints in each wire.

So my original Exchange copper distance is now 1,286 Metres (existing) + 2 times 50 Metres (new Double Link to pick up the VDSL at the FTTC Cabinet), coming to 1,386 Metres, whilst the D-Side has been effectively extended from 250 Metres originally to 350 Metres. (Edit ~ 300 Metres)

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The one thing that I could not establish is whether there is a VDSL HF Rejection Filter built in to the FTTC cabinet, to prevent that VDSL signal going back along the combined new short extension and old E-side to the Exchange.

It doesn't go back to the exchange as the signal only comes out of one of the pairs coming from the FTTC cabinet. The other tie pair is input only (for the dial tone).

Generally, I think there must be such a filter in the FTTC. Perhaps someone with direct knowledge of the FTTC Cabinets can clarify.

There is a filter which filters out ADSL in case the ADSL has not been removed at the exchange. No idea what the other stuff does.

Edited by troublegum (Sun 31-Aug-14 21:40:06)

In reply to a post by eckiedoo:

The working effect is to move the D-E joints from inside the PCP to inside the FTTC cabinet, thus extending the phone circuit by 2 times the link length, ie in this case by 2 times 50 Metres = 100 Metres; and with extra joints in each wire.

So my original Exchange copper distance is now 1,286 Metres (existing) + 2 times 50 Metres (new Double Link to pick up the VDSL at the FTTC Cabinet), coming to 1,386 Metres, whilst the D-Side has been effectively extended from 250 Metres originally to 350 Metres. (Edit ~ 300 Metres).

So from these two paragraphs, I take it your PCP and FTTC twin are 50m apart?

Great post by the way. Very informative!

Paul

Almost correct, Paul.

The FTTC and PCP are about 40 Metres Geographically.

Basically the E-Side locally passes the corner of my house, carrying on "northwards" by about 45 Metres to the PCP.

My D-Side leaves the PCP and heads eastwards about 125 Metres to a very small, pavement junction box (inverted elongated U, also similar used for some electrical distribution), to return 125 Metres "westwards" to my house.

At that corner of my house, there is a 1986 3 section underground chamber (replacing original 1967 single section U/G chamber); and another 3 section U./G cahamber close to the PCP.

The FTTC has been placed about 5 Metres "north" of that corner U/G chamber, with a smal new duct connecting them, so this new duct runs back, towards the Exchange.

Thus the two pairs of new links, have to head "south" for 5 Metres to access the corner U/G, to then turn "north" into the main duct, to get to the PCP - a geographic distance of about 40 metres; but needing 50 Metres of wire each, because of the ducting.

The corner U/G chamber is about 5 Metres from my front door, where the phone line apparently comes in.

All underground and installed when the estate was built, hence my not being 100% certain, but the wire at the ancient NTE seems to arrive at the cupboard from that direction.

In reply to a post by troublegum:

The "double links" you mention are the E side and D side pairs to the FTTC cabinet. The D side pair is basically an input for the dial tone. The E side pair then provides the dial tone and VDSL signal out.

He has done that wrong and would get a critical defect for that if it was audited. He should have removed that jumper wire going to the copper D side and ran a new jumper from the FTTC E side to the copper D side. Instead he has been lazy and left it in place, then just connected another jumper wire to the end of the jumper wire.

Very informative post, thank you.
I am still a little unclear on the voice side of the connection;

Assuming the engineer does the following
1. Connects the E side (exchange) pair in PCP to DSLAM in FTTC.
2. Connects the D side (premises) pair from DSLAM in FTTC to D side in PCP.

Does the voice side continue to use the E side copper pair from the PCP back to the exchange?
i.e. it there is a fault or poor connection on the E side copper pair to the exchange, this will this affect voice side, but not data.

I have a incredible stable DSL connection (200m from PCP/FTTC cabinet), in fact the line rate went up after the 10 day training period, but since activation, I have a noisy voice line, and am trying to pinpoint the possible cause before raising it with BT.

Thank you