Cabinets, Cross Connection No's 1, 2 and 3


Initially wiring was all overhead, but as more people went on the phone the number of aerial cables became obtrusive and congested.

Mutli-core cables then came on the market and the overhead wires were moved to an underground network of cables.  These cables were fed from the exchange and divided into smaller cables.  These cables provided no flexibility as each division was a joint.

From 1945 onwards a new method of distribution was adopted.  Cabinets were generally the first cross connection point from the exchange and they may also feed Pillars which in turn would have fed the Distribution Points (DP's).

The Cabinets and Pillars afforded flexibility in the network as any incoming wire could be connected to any outgoing wire.  The connection made by a piece of two wire called a "jumper wire".  Before the 1970's Cabinet terminations were actually screws which clamped the jumper wire or in the case of a through connection (i.e. wire 10 to wire 10) then two metal bridging pins were used (See picture further down page).  If the screws were over tightened the heads would shear off, to prevent damage.

Enclosed type connection Strip Connection strip components

Bridging Pins No. 1 - Used on open type assembly - obsolete.
Bridging Pins No. 2 - Used on all assemblies except PC/100 type - White plastic head.
Bridging Pins No. 4 - Used on PC/100 assemblies - Yellow plastic head.

When jumpering, 12.5lb 2 wire was used.

As telephone penetration rose, Pillars were not normally installed and the Cabinets feed the Distribution Points directly.

Pillars were painted dark green and made of cast iron.

Cables from the exchange are terminated on the 'E Side' of the terminating strip whilst the outgoing distribution cables were terminated on the 'D Side' of the strip.

In the early 1970's the screw style terminal blocks were replaced with plastic formers and the cable wires just pushed through numbered holes and left hanging.  Connection was made with grease filled crimps (See picture below).

The largest Cabinet can take 800 pairs in and out and the largest Pillar 200 pairs.

 

Open style connection strips
 

Pillar with crimped connections (Yorkshire Area)
The mounting is called a Strips Connection No. 1


Strips Connection No. 1 showing layout and numbering


Yorkshire style mounting showing wire routing
 


Pillar showing screwed connections
on enclosed type of strip


Close up of screw type blocks in a Cabinet with enclosed strips
The white dots are the through connection pins


Cabinet, Cross Connection No.2 with local footway joint box open to show cable joints.  The cabinet is immaculate
and has probably just been installed.
The oblong units on the door are metal cases with desiccant in them.  There is a small window in
the middle of the box to see when to change them, as the desiccant goes pink when saturated
with water (they would then be dried out in an oven).  They were used to stop the cabinets
from getting damp inside.

 

Midland Region layout in a Cabinet, Cross Connection No. 1 (single door).
The strips were parallel and they used white crimps to connect the wires.
The white crimps were later replaced by grease filled crimps, coloured blue.
The dial at the bottom of the picture is a pressure gauge.
Main cables between the cabinet and exchange were pressured to prevent ingress by water.
An alarm went off in the exchange if the pressure dropped beyond a pre-defined reading.
The Yorkshire area also tested an upright assembly, which was adopted as the standard.



 

 

 
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Last revised: May 04, 2020

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