A friend of mine has an unknown device fitted to the BT wiring outside his house, and wants to know what it does. It's a long cylinder shape and is made by 3M corporation. Image linked below:

http://www.peterbaran.com/misc/device.jpg

it just seals the join in the cable and keeps water out

Interesting. Why is it so large if that's all it does?

I think it's a joint for a larger number of lines than the normal line that goes to a property. This is the sort of thing that you would expect to see in a block of flats or the like, though I have seen it linking up a row of houses where the cable runs along the building from one end to the other rather than all coming off a pole.

Yep! Waterproof junction box, as said.

Standard phone wiring uses 6 wires, There are 6 pins on the rj11 jack, 2 currently not used, 4 used for distributed wiring .........

http://www.wppltd.demon.co.uk/WPP/Wi...telephone.html

I think that you are little confused between the external stuff and Internal wiring "Standard phone wiring" does not use six wires, The external telephone wiring to premises is generally a two pair cable although only one pair is actually used; the other pair being a spare. Even in large junction boxes each circuit is only carried on a single pair.

BTW, even Internal wiring only needs one pair. The ring circuit hasn't actually been needed for donkey's years and the other three wires have never been used.

Only a sinlge pair from exchange. No recall. We don;t now have party lines (listening to neighbours used to be fun).

I believe any BT installed extensions after the master socket still use all 6 wires.

Nope. Not that I have ever seen. 2, 3 & 5 are usually connected even though 3 is unnecessary. Some say that BT have connected 4 for neatness in the past but I haven't come cross it. The only time I have found all six connected was when the work was carried out by the householder or sparkies and the like. ('Cos it's wrong.)

The only time I have seen more than 2,3 & 5 connected is for office PABX systems. Very often 4 is also connected as an earth for extra features like recall and the like. For example when you want to forward a call to a different extension.

I have also seen systems which use 1 and 6. These would be specialised systems that have clever extension phones with loads of non-standard features. The extra pair is used for data signalling back to the PABX unit.

"Although pin 4 has no function in a domestic installation it is usually connected for the sake of neatness. The quality of wiring carried out by many older BT wiremen is often approaching art in its perfection."

http://www.wppltd.demon.co.uk/WPP/Wi...telephone.html

Phone cable is 6 core. You're adding an rj connector, Y not all 6 wires?

I know about that statement on that site and I do not agree with it. Posting something on a web sites doesn't make it true.

I'm not sure what you mean by: "Phone cable is 6 core. You're adding an rj connector, Y not all 6 wires?"