2nd phone line wiring to NTE5a.

Can someone help with what the wiring to a NTE5a master socket on a second phone line would be?
There are 2 phone lines into the property. The main telephone line and a second line that goes into a different room. The second line is wired from the main line. It uses green/white and white/green wires. I presume the green/white white/green is because it is a second line.
The master socket on the 2nd line is not a NTE5, It is a LJU2a. The connections on the LJU2a are:

1-green/white
2-blue/white
3-orange/white
4-white/green
5-white/blue
6-white/orange

There are also red/white white/red wires but these are not connected to anything.
From reading around the internet the orange combination wires are the ring/bell wires and do not need to be connected.
On the back of the NTE5a box there are only 2 IDC connectors. A and B. These would be for the blue/white white/blue wires i presume. There is nowhere to connect the green/white white/green wires. So connecting just the blue and white combinations means the line would not be connected.
On the back of the faceplate there are connections for an extension to be run from it. This has 3 IDC connectors numbered 2, 3 and 5. In the LJU2 that is there now the green combination are connected to 1 and 6. (There will not be an extension run though)
Now if a BT engineer was to connect a NTE5a how would they connect the blue/white white/blue and the green/white white/green wires?

In my 2-line installation the property is supplied by 2 pairs. Both pairs arrive at the 1st NTE5a where 1 pair is connected to its A&B terminals while the other pair just passes straight thro' onto the 2nd NTE5a for its A&B terminals. I don't know their colours.

On the LJU2 connectors, only 2 & 5 are needed as the A&B terminals and so can move to the back of an NTE5a.

Hello XRaySpex.

There are 2 lines in the property. They are 2 different telephone lines. Different phone numbers and different accounts with BT. Even though they share the same drop cable entering the property they are independent of each other.
The drop cable has a small box attached to it. There are 2 cables exiting from this box.
The first cable runs to a NTE5. This is the main phone line. It is connected to the NTE5 with just the 2 blue/white wires going to the A & B terminals.
The second cable is for the 2nd line. It runs to the LJU2 master and is connected with the blue/white combination wires and green/white combination wires. Both orange/white wires were connected but have been disconnected and everything still works fine.
From reading up it seems that the green/white combination wires are what separate the 2 different lines making them independent of each other.
On the second line if the blue/white wires were to be disconnected from the LJU2 and connected to a new NTE5 the line will not work for telephone or broadband and there are no other terminals on the NTE to connect the green/white combination wire.
I was wondering how a BT engineer would wire the NTE on the second line. Would the engineer use just the green/white combination wires and connect the to the A & B terminals or would they connect both the blue/white & green/white wires combination wires to the A B terminals.

In reply to a post by funkydan:

There are 2 lines in the property. They are 2 different telephone lines. Different phone numbers

Yes, I know! That's what I'm talking about.

The 2 cables are independent of each other. Only 2 wires from each are needed to feed a socket's A/B.

OK, settign aside the slight iffyness of working on the wiring beyond the NTE, you might be over-thinking this.

The drop wire contains two colour-coded "pairs".

Each pair is two wires, which are what end up, eventually, at the A and B terminals on each NTE.

So, go back to the drop wire, and just follow each wire through to the A and B on each line - the colours may not be consistent, there may be wires connected to terminals that don't have to be, etc. You only need two wires on the back of an NTE - the LJU in the middle sounds like it's confusing matters.

Top tip - you will find approx. 50v across each "pair" - don't be a klutz and try and measure across pairs, and definitely don't use any sort of Megger-type device, a basic multimeter is all you need.

Have a look at http://www.telephonesuk.co.uk/wiring_info.htm for info on colour codes and the like.

In reply to a post by shtu:

OK, settign aside the slight iffyness of working on the wiring beyond the NTE,

It is illegal to work on BT property. The wire entering the property and the master socket are classed as BT property and i would not attempt to fiddle with these. As i said i was just wondering how a BT engineer would wire a NTE.
It is permissible for a homeowner to run an extension from the master socket as any wiring or equipment after the master socket is not BT property.
A BT engineer has told me that the green/white pair could have been wired as the blue/white pair and he would try wiring both to the A/B terminals to see which one works.

Now if a BT engineer was to connect a NTE5a how would they connect the blue/white white/blue and the green/white white/green wires?

I'd suppose that there was a junction box somewhere between the main line and the 2nd line LJU.

The 'greens' are spares also. The 2nd line leaves the main line NTE on greens and in the LJU 5 and 2 are terminated with blue/white white/blue, right ?

So just terminate blue/white and white/blue to the terminals on the back of the NTE you're theoretically fitting. Problem solved.

The BT engineer has assured me that your solutions are correct. Only the blue/white pairs terminate at the A/B terminals. That is exactly how he would do it and the it would work.
Many thanks for your suggestions and help.