How many extensions directly wired from the master socket?

[overlandrover]

Following on from my plans to use CAT5e wiring for all my phone extensions, I am about to connect my four extensions to the NTE5 box:
//www.diynot.com/forums/viewtopic.php?p=608172#608172

But before I do so, I plan to fit an ADSL faceplate
http://www.clarity.it/xcart/product.php?productid=16134&cat=262&page=1
to provide a dedicated RJ11 socket for the modem and centralised filtering for the extensions.

But the question I cannot seem to answer is how many extensions can I run from an ADSL faceplate? I'm planning to star wire the extensions from a single point (i.e. the NTE5) but is there a physical limitation to the number of wires you can fit into the IDC connectors?

Should I be using a junction box instead (like a BT78)?

Thanks again in advance for your responses.

 

[plugwash]

Generally you shouldn't try to punchdown more that two cables into one block, you'll probablly get away with a few more but the joints will get progressively less reliable. Also you shouldn't mix cable types in a block (e.g. don't try and punch down both BT spec cable and cat5 in the same block) and you shouldn't use stranded cables in punchdown blocks.

Personally i would use cat5, the tighter twists make it more immune to noise and the fact it has 4 pairs gives you a lot of flexibility.

any particular reason for going for a star wiring pattern?

 

[TicklyT]

There's no limitation on the number of extension sockets you can run, but there is a linit on the total number of devices (modems, phones etc.) you can plug into the sockets at one time.

Each device should have a REN number. The sum of all the REN numbers should not exceed 4. you may get away with a little bit more, but the system may behave erratically.

There is also the limitation of 2 wires connected in each individual IDC connector as pugwash has said.

You could run your star-wired cables to a junction box like
http://www.tlc-direct.co.uk/Main_Index/Telephones_and_Accessories_Index/Telephone_JB/index.html, and then take a single cable to the NTE5.

 

[overlandrover]

Thanks for your answers - it confirmed my suspicion that two extensions coming off the IDC connectors would be pushing it.

My choice for a star-wire configuration is because I am using an existing cupboard as my distribution hub for electricity, telecoms, TV and internet.
The broadband router and TV 'loftbox' will be located in this cupboard, and it seemed sensible to distrbute telecoms in the same way, seeing as I had the space and infrastructure to do it.

I also have a phobia about the number of connections between the intake point and the user device, so star-wire seemed the way to go!

As mentioned before, I am using CAT5e cable for BT extensions as well, so with a bit of butchery I could convert these to broadband cables in the future, which makes me wonder if installing a patch panel might be the way to go...
...but it means more connections!!!

 

[overlandrover]

OK, so I've got myself a BT77A junction box - only how do I wire the thing up??! I bought it off Ebay, but I have no instructions.

Option A
The numbers 1-6 correspond to the 6 potential connections you have in a standard extension socket, but I suspect this is not the case, especially when a BT78A has four pairs, numbered 1-8.
Would BT design a multi-extension junction box that relied on doubling-up on IDC connectors?

Option B
Am I to assume that the 1-1 pair represent wires 2 & 5 on the master socket, and the 2-2 pair represent 2 & 5 on the first extension, and so on? I'm guessing wires 3 & 4 aren't used, but I can't imagine BT desigining a unit not to use the orange 'bell' wire.

Option C
Each bank of three connectors is for wires 2, 4 and 5 only (3 not used)
But then why would didn't they number connectors 4, 5 & 6 also as 1, 2 & 3?

Are any of these correct?? Your help once again appreciated.

[/img]

 

[JOHNBOY42]

If your feeding from a nte5 to the block terminal,the only number you need to terminate will be 2,5 and 3........1,4 and 6 are only for system extensions.....anyhow all the numbers on the left hand side are only bridged to the corresponding numbers on the right( not sure where the diagrams come from?) but terminate the white/blue on no2,blue/white on number5 orange/white on number 3 in the nte5 ,then the same in bt78 then splice your extensions off this using the same numbers and colours in series.
Use a proper krona connection to punch down in the bt78 because if not punched down correctly you will have a hr dis causing endless adsl problems........what you are best using is a wireless router provided free with certain isp,s ,but if you want to go for wired use cat5 wiring and as for the bt78 connection,take out the terminal block and crimp or solder the wires together and just use this bt78 as a housing


" here endeth the lesson"

 

[JOHNBOY42]

overlander try this websire its full of info,but if you need snd more post it on here
www.adslnation.com

 

[bernardgreen]

Option A is the corrrect one.

Note that Star wiring can make fault finding more difficult when looking for a shorted pair.


Option B will short out the line

Option C will connect only extension 3 to the line

 

[overlandrover]

Thanks for your answers, guys.

...all the numbers on the left hand side are only bridged to the corresponding numbers on the right...

Hmm, just as I suspected. So this BT77A junction box isn't really suited for acting as a hub for star-wired extensions, especially as you shouldn't put more than one wire into an IDC slot. Maybe I should use a BT89A instead, wiring a bridge between points 1-4, 2-5 and 3-6. This should allow me to take five extensions off the junction.

Over the weekend I had a look at Homebase and B&Q for their BT junction boxes. Interestingly, they both use screw-down connections instead of IDC. Is there any advantage of this other than being able to dismantle it again later on?

...take out the terminal block and crimp or solder the wires together and just use this bt78 as a housing...

Intersting idea. I guess I should have mentioned that this BT77A junction box isn't actually going to be visible - it's going to be hidden in some trunking inside this cupboard. What's stopping me from using a simple terminal strip instead? Or perhaps a piece of Vero board?

...star wiring can make fault finding more difficult...

How is that, then? I would have thought all problems could be be traced back to the hub?

...you are best using is a wireless router...

These extensions are purely for BT - I have a separate set of CAT5e cables extending from a router located adjacent to the NTE5 socket. I've never had any luck with wireless routers, hence the cables!

One day I'd like to rig up all the BT, internet and TV distribution through a patch panel, but that's in a few years. Hopefully this CAT5e star wiring pattern will future proof me to some extent.

 

[Stozzer]

If you have the space why not terminal block/solder all the same coloured wires together at one end then have only one wire comming from it that you can punch into the IDC

After all your not using all the wires at the same time (unless you plan to have 4 people in 4 rooms all talk to the same person on the phone at once?

 

[bernardgreen]

...star wiring can make fault finding more difficult...

How is that, then? I would have thought all problems could be be traced back to the hub?

Its a case of personal preference. Looping from socket to socket, if I know the route, means one disconnection in the middle identifies in which half of the wiring the fault is located. The next disconnect brings it down to one quarter of the wiring. So a fault in an eight socket "radial" can be found with just three disconnects.

Star wiring can also introduce echos from un terminated cables which while not a problem on speech can disturb data signals.

And my experience id Murphy's law applies and when looking for a fault on a star plan it is always on the last circuit that I diss from the bus

 

[Sureitsoff?]

OK, so I've got myself a BT77A junction box - only how do I wire the thing up??! I bought it off Ebay, but I have no instructions.

Option A
The numbers 1-6 correspond to the 6 potential connections you have in a standard extension socket, but I suspect this is not the case, especially when a BT78A has four pairs, numbered 1-8.
Would BT design a multi-extension junction box that relied on doubling-up on IDC connectors?

Option B
Am I to assume that the 1-1 pair represent wires 2 & 5 on the master socket, and the 2-2 pair represent 2 & 5 on the first extension, and so on? I'm guessing wires 3 & 4 aren't used, but I can't imagine BT desigining a unit not to use the orange 'bell' wire.

Option C
Each bank of three connectors is for wires 2, 4 and 5 only (3 not used)
But then why would didn't they number connectors 4, 5 & 6 also as 1, 2 & 3?

Are any of these correct?? Your help once again appreciated.

[/img]

re option A you can also feed an extension or daisy chained extensions from the terminals that come in from the NTE5