Twisted Cable

I am having trouble telling whether that phone cable in my house is
twisited. Could somebody leave some links to Twisted and untwisted
phone cable. Also what problems i could have with a Untwisted cable.

 

Most telephone wiring is twisted. Just look to the individual wires and if
it's twisted, then there will be pairs of wires twisted round each other.

An untwisted cable is just that, untwisted.

 

Also what is the correct way that a 3 way IDC junction box should be
wired

 

Not quite - there is the earlier telephone Quad, 4-wires, usually
in a thin grey or cream sheath, all 4 have a long pitch twist, as
a bundle. In this case the insulation of the wires is commonly
solid colour.

Then there is twisted pair,
comprising an even number of individual wires, where
two wires make a pair, with each pair twisted together.
Colour coding is commonly solid colour + same colour
with stripe to distinguish both the individual pairs and which
wire is which in each pair.

So you can have 4-wires made up as two twisted pairs,
or 200 wires, laid up as pairs, to make the 100-pair,
commonly used street or underground distribution
cable between exchange and street cabinets.
You can get cables with greater than 100-pairs
but the world is gradually moving to fibre.

For phone use there isn't much difference in
performance between quad and twisted pairs
the phone still rings and voice quality is
adequate.
..
In a high noise environment (microwaves,
energy saving lamps, boiler ignition systems,
Dect and mobile phones, fluorescent lamps,
power tools) the twist in twisted pair will help,
but may nor completely eliminate BB interference
from the above sources.
The same applies to rwisted pair Ethernet.

 

The rate of twist is quite low. It's not readily visible froma casual galnce. In
fact you'd have to stipa piece of acbelt to bu sure.

I was under the impression that the cable with the solid colours ( orange blue
green and white ? ) is untwisted.

Graham

 

it is twisted but not as tightly as the newer cables

 

Right, so it'll have poorer rejection of RF especially.

Graham

 

The old GPO cable contained blue/orange/green/brown wires.
The twist/lay of this cable was quite poor and particularly, the
unbalanced nature made it susceptable to interference and one could not
be sure the twist was continued up to the joins/sockets.

I recently cut out a length of this for someone and it made a huge speed
improvement.

Mike