Why Do I Have 3 Master Phone Sockets?

[Rossua]

I am about to get two new interior doors fitted in my living room plus skirtings, and I had to remove telephone cabling passing through the old door frames. As it is very scruffy I will install new solid copper cabling after the new doors go up.

However on disconnecting I realised I have THREE master phone sockets - one front lobbie, one living room, one kitchen - all with old pre-1991 BT Phone 'T' logo. The latter is just a spare for now.

Plus the main Virgin Media phone socket in living room, that comes from the outside.

I wonder why have I got 3 master sockets? Should I replace them with 2 slave sockets, leaving only one? What are the correct slave sockets to buy? I see them on EBAY - are these fairly straightforward?

In the photo you see a master socket in front lobbie has 3 sets of wires on the IDC's - a VM, an extension run, and a unused old BT landline leading via loft to a telegraph pole.

Kitchen socket has two, with one to upstairs (unchanged). Living room is the end of the line, with only one set of wires to it.

I am confident in replacing like for like, but have always read that only one master is needed, all others should be slaves - I am confused - multiple masters appear to work! But could it cause problems in future eg if I switched to ADSL broadband ?

Please advise thanks!


VM Socket:-

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• Rossua
• 2 Dec 2014
• 1

Front lobbie :-

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• Rossua
• 2 Dec 2014
• 1

Living Room :-

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• Rossua
• 2 Dec 2014
• 1

Kitchen :-

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• Rossua
• 2 Dec 2014
• 1

 

[sparkymarka]

You could just cut out the capacitor , but others may disagree. To be honest most people have a dect phone with slaves so only one socket is required depending on your broadband service/ location.

 

[steve1976]

You could just cut out the capacitor , but others may disagree. To be honest most people have a dect phone with slaves so only one socket is required depending on your broadband service/ location.

in the old days it mattered if you had too many master sockets because you were only allowed a ren of 4(ringing equivalent number.these days it`s not so much of a issue so I would leave the master sockets in then you only need 2 wires between each socket

 

[bernardgreen]

Too many master sockets with capacitors can appear to line testing as being a fault.

The REN ( Ringer Equivalence Number ) determines how much AC current flows when the bells are being rung. Too much AC current through too many ringers ( REN greater than 4 ) can result in the exchange thinking the phone has been picked up when it hasn't been picked up and this results in "ring trip"

 

[cajar]

too much REN doesn't seem to cause ring trip, just makes the ringing very faint, sometimes imperceptible. maybe it goes faint first then if you add an outrageous number of phones to the line it would maybe start showing ring trip? but I've never seen that. not sure if it will actually trip unless it sees less than 1k ohm resistance a-b down the line.

 

[Rossua]

I am wondering if the main master socket (the one the VM engineer connected the incoming VM phone socket to - ie in my front lobbie) being very old (pre 1991) would work OK with 2 new slave sockets - there might be some compatibility problem? Maybe 3 masters were put in for a reason - or did they only have masters back in pre-1991 era ?

My researches have taught me these are the following connections for phone line on the 6 pin IDC connector block :-

1 N/A - No connection
2 Blue with White Bands - Speech and Ringing
3 Orange with White Bands - Ringing
4 White with Orange Bands - Not used but usually connected for neatness
5 White with Blue Bands - Speech and Ringing
6 N/A - No connection

And I plan to connect pins 2,3,4,5 each time.

I decided to get Solid Copper phone cable (2 pair) rather than the cheaper CCA (Copper Clad Aluminium) or CCS (Copper Clad Steel), as it is recommended (by EBay seller denismiley) for broadband use, as opposed to purely for phone/fax/etc, for which the cheaper cables types are OK.

 

[Spark123]

You only really need one master socket, last time I used CW1308 (solid copper twisted pair) cable to interconnect the slave sockets and get a reasonable speed 18mb/s.
When used for broadband adsl I was told only to connect cores 2 and 5 but as you don't have that 2,3,4 and 5 would be a good idea with 2 pair cable.

 

[cajar]

they're line jack units 2/1, ie small extension sockets that come with a capacitor. most of us had limited space in our van so carried limited stock, so it made sense to choose these from the stores, because they would still work even if you only had 2 wires available, whereas the ones without the capacitor would not ring without the 3rd wire carried through, meaning sometimes running a new cable.

most bang for your buck would be to remove the ringer wire from terminal 3 on all sockets. don't think you'd see much benefit recabling and running as master/slave tbh.

 

[Spark123]

The op wants to replace it for aesthetic reasons

 

[Rossua]

Yes that's right the cabling especially is very scruffy and ancient looking, all flaky paint over it - a nice new white cable will be in order