Overhead Wiring


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In the early days of  the telephone all cabling, once it had left the subscribers premises, went overhead back to the exchange.  Originally this would have gone straight back to the exchange but as telephone numbers grew, so did the number of wires.  Each line consisted of two wires and these were run to poles and tied to insulators.

The wires became a spiders nest on top of the exchange buildings and was unsightly.  Poles in towns soon became over laden and wires could come into contact with trolley bus wires.  So the wiring from the exchange to a local or distant distribution point went underground.  Helped by technology the wires were reduced in size and underground cables became cheaper and more reliable.

Today the overhead distribution is generally fed from a local pole to a building.  Pole routes are a thing of the past in most places, but where the route is long it may still be cost beneficial to run the wires overhead.  Open copper/cadmium wires are no longer used as a twin wire cable called dropwire took over.  This was replaced in the 1980's with a 4 wire cable that also consisted of steel strengthening wires.

Smallish wire derrick on the roof of an Exchange building
 

Large wire derrick on the roof of Avenue Exchange, Lime Street, London (1909)
These have been known to collapse!
 

Another roof top wire derrick - what a mess!
 

Pole top distribution - picture probably dated early 1960's as this pole is well loaded
as the subscriber base rose significantly.
Note that each customer is fed by two open copper wires.
The pole is finished at the top with an aluminium finial
 

Mid 1960's with the older style ring but with new type drop wire

 

The above is two core overhead cable - called Dropwire  No.1 and No. 2 were
the original Dropwire, which were superseded by Dropwire No. 3 and No. 4.
Dropwire No. 3 comprised of steel wire coated with copper.  One nick in the copper
coating and corrosion set in.
 

Dropwire was supported by clamps.  The curly No. 3 is all you will see today.
 

Ring type distribution (2 rings in situ) on a pole that once had wooden arms (note cut outs in pole).
Points to note are the bass bag for holding tools and the leather safety belt
 

Late 1960's ring type pole distribution with drop wire radiating.
Points to note are the use of the man made pole belt, goggles and safety
hats instead of a flat cap!

 

 

 

 
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Last revised: March 21, 2021

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