On Sun, 20 Nov 2016 01:35:41 +0000, The Natural Philosopher
wrote:

On 19/11/16 22:15, Scott wrote:

Drifting from the topic (as is often the way) it is interesting you
should mention DC supply. Was this commonplace in the UK

No, it wasn't, but ISTR being t0old about 205V DC or thereabouts way
back when.

It was very common in the early days when a "Power Station " could be
little more than shed with a small engine and a dynamo in it
or a converted water mill with a turbine serving just a few customers.
I can't work out how to link directly but under the heading
Gen.Stations in the Menu on this site
http://www.swehs.co.uk/tactive/sparkhome.php
there is a list of many of the known plants in the South West Counties
and for a good number of entries the current produced.

The pattern appears to be 1900's to 1920's DC after that AC as some of
the early stations were closed or modernised as areas served got
bigger often accompanied by a takeover by a bigger group such as the
Chelmsford based Christy Brothers who beyond the reach of the 1947
act that nationalised the industry still ran the power station on
Alderney till 1979.
http://emep.worldonline.co.uk/SWEHS/docs/news15su.html


http://www.vintage-radio.net/forum/s...ad.php?t=41380

suugests it hung on into the 60's in some areas.

Into the 1970's in a couple of places ,
Reading was one of the last ,and I remember reading in the regional
paper that Exeter finally had its last enclave around the canal basin
converted around 1970.
In a book I have "called" Southern Electric , A History" they still
had 39 Customers being served by DC in the Bournemouth area in 1974
though that was more down to the customers choice by then , The last
ones had the DC supply terminated in 1979.according to the book in
1974 it cost over £2000 a year to provide the DC service against an
income of £136.30.
When the Southern Electric Board took over 25 separate power stations
in 1948 they had over 40,000 on DC 20,000 of which were still
unconverted in the late 50's .
If that was similar in other boards then DC was hardly uncommon even
at that stage.

Remember the CEGB wqas created post WWI, and the 'national grid' grew
out of that.

Drew a lot on the expertise NESCO who had already built a grid
around the North East out from Newcastle from the early 1900's.
ISTR their network used 45 Hz till it was standardised.
https://en.wikipedia.org/wiki/North_...Supply_Company



In our old house some of the sockets had very heavy springs and I
remember being told at a young age this was because they were designed
for DC (to prevent arcing).
I lived on a boat for a few years that had 220 DC equipped with the
correct light switches , basically the spring mechanism would not let
the contacts be moved gently but a lot of pressure till when they
actually sprung they moved quickly.
its a while ago so memory has faded but I think they had two sets of
contacts as well. Externally they looked just like old fashioned round
light switches and many house that had DC would have used the same .
There would be no problem using them after AC conversion and being
robustly constructed would last for years giving away to fashion
rather than faults.
We had another type that had a big side lever sticking out of a metal
box like a miniature old fashioned mains isolator never took one
apart as it obviously contained Ping****its and getting spares for a
switch that had embossed it on MFGRD by the Parker Pen Company seemed
unlikely.


I have Googled many times since and been
unable to find anything on any 'AC switchover'. I was also told it
was related to the closure of the municipal generating station (for
the trams) and introduction of the National Grid but again I can find
no support for this..

It almost certainly was. The rollout of 2540V A/C 50Hz as the 'standard'
happened post War, and was intimately connected to the construction of
the 'national grid'
The 1st grid was fairy well established by the end of the thirties
and it was the 1926 act that created the Central Electricity Board
that set the std for 50Hz, whether that act also set the domestic
voltage at 240 AC as well it seems it took the nationlisation of the
electricity industry and the boards taking over in 1948 to really get
standardisation under way. And adding to the workload was the rural
electrification programme which the boards had to undertake bringing
supplies to areas that the previous private generators could not make
a commercial case for.

So about 20 ish years to convert most with a few pockets a tad longer.


G.Harman