Can someone please clarify the position with regard to the bell wire in domestic telephone cabling.
Some web sources imply that it is no longer necessary with modern phones. Other web sites show each extension connected with three wires
- the third being the bell wire.
I am about to install additional extension sockets - primarily to allow connections for a Sky digibox and I want to get by on one pair, if that will work.
Some sites suggest that getting rid of all the bell wires helps improve one's broadband speed.
The truth is that some phones will not ring unless provided with a ring signal on Pin 3. Some phones (probably most modern ones) have their own ring capacitor, and will ring quite happily on a 2-wire circuit - with only 2 and
5 connected.
All is not lost though because you can get away with only using 2 wires as long as you provide a ring capacitor at the point where the phone plugs in. The easiest way to do this is to use a plug-in ADSL filter, all of which have ring capacitors on their phone socket. If you're using broadband over the telephone wire without a faceplate filter on the master socket, you'll need a plug-in filter on each extension socket anyway. Even if you *are* using a faceplate filter, it will do no harm to use an additional plug-in filter for any phones which refuse to ring without one.
And yes, getting rid of the unbalanced bell wire may well improve broadband speed by reducing noise pick-up.
3 core extensions will work all phones, but can indeed affect broadband data.
2 core extensions with no added ring capacitor will work some phones, not all.
2 core extensions with an added ring capacitor at the end effectievly recreate the 3rd wire, and work perfectly with all phones, and don't affect broadband.
Two wires will be fine in 99.99% of cases - occasionally you will find a phone that requires a bell wire - however inserting an ADSL filter in the phone cord will usually solve this. However when you do install your wiring ensure that you use the correct telephone specification cable (twisted pair); some people will suggest using CAT5 instead of telephone cable, that's also fine, - but personally I've always found CAT5 to be a bit obtrusive in a domestic environment if you can only put it around the skirting. Some extension kits from the likes of Been & Queued provide a flat cable that isn't twisted and that can/may play havoc with your broadband.
The bottom line is that a properly installed phone line and extensions should not cause problems - but in the case of all deregulated services there are now lots and lots of bits and pieces for the consumer to use and they may not all be compatible or of equal quality. Long gone are the days when the Post Office would test anything new for so long that it was obsolete by the time it came out to the customer :-)
An IPlate is NOT an ADSL filter!. It is designed only to reduce the=20 level of any interference signal picked up on the "pin-3" ring wire.=20 Hence, when this is coupled, via the ring capacitor, to one of the=20 signal pairs, the interference signal will, hopefully, be low enough not=20 to cause a problem for the ADSL modem.=20
If you install and ADSL filter in place of the removable faceplate of=20 the NTE5 master socket, e.g.
formatting link
then installing the pin-3 ring wire in the phone extension cables (and=20 never in an ADSL carrying extension cable) from the connectors on the=20 back of the faceplate will be OK in 99.999% of cases.
Even better, If you decide not to install the pin-3 ring wire in the=20 phone extension cables, then a UK sourced plug-in ADSL filter inserted=20 into the slave socket used by a non-ringing telephone should restore the=20 ringing. In this case, this filter isn't doing its normal job of=20 removing the ADSL signal from getting into the telephones. All it does=20 is restore the ringing signal on pin-3 of its output socket for the=20 local telephone.
--=20 John W I you really want to mail me, replace the obvious with co.uk twice
Not necessarily - and certainly not for the reasons which you assume.
Firstly, an I-Plate *isn't* an ADSL filter per-se - it simply filters the bell wire. If you're only using 2-conductor extension wiring - with no bell wire - an I-Plate is pretty much a waste of space. However, because an I-Plate isn't an ADSL filter, you *still* need plug-in filters at each extension socket. So *they* will provide you with a ring signal on Pin 3 regardless of whether you have 2-wire or 3-wire extensions.
Now, if you have a *proper* filter at the NTE5 - i.e. a filtered faceplate which splits the analog and digital signals at the point of entry - you still have the choice of 2-wire or 3-wire analog extension wiring. You no longer need plug-in filters to make ADSL work *but*, if using only using 2 wires, you may *still* need one or two plug-in filters to make your extension phones ring, if you have any without their own ring capacitors.
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