Does anyone know why slave sockets are daisy chained rather than star wired. Does it make any difference? (BTW, without being funny because I know people are just trying to help, I'm not looking for educated guesswork but definitive answers.)

your primary scoket will have a capasitor in it the secondary should not , its daisy changed so the capasitor in the main socket makes the slave phone ring

Although most phones these days, being designed for the international market, will ring even if the master capacitor has blown (mine was blown by a nearby lightning strike and I didn't find out for a year).

Sorry if this sounds horrid, it is not meant to, BUT I did ask for a proper answer not an inspired guess.

The expression is "daisy chained" - not changed - and refers to a wiring topology. Second the capacitor (capasitor?) is still across the master socket pair even when the slaves are star wired. Finally the capictor does not "makes the slave phone ring".

I know people like to be helpful but I'm trying to fix a real problem.
Last edited by beerhunter2 : 11-12-2006 at 21:55

There is no reason why phones are 'daisy-chained'. It's usually done that way because that's the result that the BT sanctioned 'user-wiring' tends to lead to.

I have wired three socket systems as a star. Electrically the topology is identical because even a daisy-chained system is, in reality, topologically, a star since each actual phone is on its own spur.

Plus the most you can get in a star configuration using standard pushdown terminals will be two wires. If you try anymore then they start to fall out. Aesthetically a star configuration looks messy, and since these would tend to be used for residential applications, people won't put up with a mess - particularly if you're talking 3+ extensions all coming out of one master socket.

Businesses would tend to be taken out of this equation since they tend to use PBX's more, where the CCU is the one terminating point and spurs are not used.

You say you're trying to fix a problem but don't say what the problem is?

For reference, on a standard service you need legs A+B to activate a line, terminating in a master socket. The capacitor isn't essential itself for the first phone these days other than to allow your telco to test the line. The capacitor comes far more into play for extensions, and an extension will operate a phone if legs 2 and 5 are connected, but for it to ring you need leg 3 connected also. You'll tend to find if you're having ringing problems that it's either a disconnected leg 3 (such as a break in the cable) or a capacitor issue. If this is the problem you're having but you still have a dial tone, you can try using the wire normally used in leg 4 as this isn't used on residential lines.
Last edited by CitySlicker : 14-12-2006 at 19:51

most adsl filters have an in built capacitor that will make the phone ring so doing away with bell wire.

The problem is a customer with star wiring which I need to validate.

I'm afraid that you are very out of date with the ring circuit bit. As I said at the begining I'm not trying to be funny but I am looking for real life answers not stuff out of an old book. (Which I've read BTW.) Are you in the trade of just quoting from the old book?

The facts about the topology of the circuit are a mathematical certainty.

In reality phones are never daisy-chained since, as I said above, each phone is on its own local spur (the lead from the socket to the phone), so all multi-phone systems are, actually, star systems.

Thus a system which just happens to 'look' more like a star is just as 'valid' (electrically) as one which appears to be a daisy chain (but which is actually no such thing).

Thanks for that. I've been over it with my O level Physics, OU electronics and Systems Engineer experience and could not find any valid reason for daisy chaining over star wiring. Anyway I've told my customer 'not to worry' - something SEs are schooled from birth not to say.

Just to add, the "bell" circuit on the current BT phone wiring system are wired in Parallel, it used to be in Series, as long as terminals 2-5-3 in the "face plate" of the NTE5 and beyond are connected ( no reversals) it matters not how the actual physical wiring is therefore run, be it radial or daisychained, you can spur off anywhere, but only 3 wires per insulation displacement terminal.. hope this helps

I am far from out of date as this is common in many systems.

You are incredibly arrogant and rude in that response, and I don't feel I want to waste anymore time replying to someone who is so derogatory to a person assisting them.

I hope others who are thinking about helping may think twice that you may be pushed into a rude response like this!

I am really sorry cityslicker. I really did not mean to offend you - or any one else for that matter. I did make it clear that I was looking for help with a real situation and did not need guesswork or old stuff even if people were trying to be helpful - which I am sure was the case in your post.

Having said that I felt that I should point out that some of the posts contained errors (however helpful people are trying to be) in order that others who read this do not get mislead.

For example connector three has not been needed for years because modern phones in a domestic environment do not need it. In fact it causes problems with ADSL circuits.

My applogies again. My only defence is that written English is not as good as verbal. (80% or which is NVC.)

As a telephone engineer with almost 30 years experience including earned a living working on this installation & this type of equipment perhaps I should have a go at answering your question!

It doesn't matter if you daisy chain or star connect your LJUs together. The key points are these:

The first LJU should be the master, the LJU fitted with the capacitor & resister and it should have the incoming exchange line connected onto it. (But only because its good practice not a technical reason) The incoming exchange line will be connected on to terminals 2 & 5. This LJU forms the NTP. The network terminating point for the PTO.

From then on you can connect onwards as you wish.

Star out from the master LJU if you wish to secondary LJUs.

Daisy chain from the master onto a secondary and then star out, the choice is yours.

Just a point you have to take care with is the number of wires that you can IDC on a terminal - 3 is about the max.

And you MUST, as it is good practice between all secondary LJU and the master connect all the terminal "2"s together, all "3"s together, all "4" together and all "5" together.

2 & 5 being the line and 3 & 4 being the ring and earth (if connected) wires. The ring wire being needed so as to ensure that those phones without internal bell capacitors will ring.

And just one final point remember that the MAX REN is suppost to be 4 after which bells and sounders may not operate. But the REN is controlled by the type of device that you plug in to a LJU and not the number of LJUs on a circuit.

try this link

& this one

I hope my post has been of use
Last edited by mrfreeview : 27-12-2006 at 17:55

Mrfreeview - I'm betting you're still going to be picked up on lots of things. Both of us know 3 and 5 should be connected, yet I was told I'm very out of date and I'm in the habit of quoting from the old book!

Despite all this, the OP keeps prattling on about having to 'validate' a 'problem', and in reality we still haven't been told what exactly the problem is. Bit too rude replies for me to give any further advice.

I think OP is quite happy now. It was a particular wiring system that he wanted to check, rather than a problem, so the replies based on topologically identical wiring were probably, actually, more useful than those based on telephone technology explanations (although I've learned something from those, so thanks to those who did so for posting).