Drifting from the topic (as is often the way) it is interesting you should mention DC supply. Was this commonplace in the UK (I know it was in New York - battle of the currents) and if so when did this change?
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 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..
You won't get a adequate fault current through too many cascaded leads, but fitting all extension leads with 3A fuses in case someone may cascade them seems a bit self defeating.
Prior to the national grid there were significant local variations in generation - so some areas would have had DC generation. (ISTR recall that London alone had 24 different standards of voltage / frequency etc).
No, it wasn't, but ISTR being t0old about 205V DC or thereabouts way back when.
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suugests it hung on into the 60's in some areas.
Remember the CEGB wqas created post WWI, and the 'national grid' grew out of that.
Prior to that time you got whatever voltage and frequency, including DC, the local power company gave you.
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 original standard was 100-110v ac or dc. This is around the ideal voltage for filament lamps. Most moved on to anything in the 200-250v region ac, but 100/110v dc areas remained into the 1950s.
To make matters worse there were negative and positive earth dc supplies. Radios need mods to work with positive earth. One of my radios is 110v positive earth dc.
How do you chose the "correct" fuse for an extension lead (assuming the lead is designed for a 13A load)?
Are you proposing changing the fuse in the plug depending on what you have plugged into the far end?
(and for most people the choice of fuse is 3, 5 and 13A - while non standard options are available from more specialist places, they are not commonly found in most shops)
Fault protection is what prevents fires. Modern kit built to recognised standards will be adequately protected by a 13A fuse in the vast majority of cases.
Ancient kit may require lower fusing, however I would not expect most modern users to to be able to identify it.
Substandard imported tat is another matter - plenty of it does not even have provision for fusing!
I can't imagine why you assume extension leads are all 13A rated. I assure you they're not. 10A leads get a 10A fuse, 5A leads get a 5A fuse etc. Hardly a challenge.
Have people not got internet now?
Hence why people should pick the fuse according to power consumption
Much does, and again the reason for a suitable fuse is obvious.
which at the turn of the century was typically about 100v
3v 100w lamps lose a great deal of heat from the filament ends, bad news fo r efficacy. It is not ideal.
You need to prevent touching of chassis, grub screws etc. You need a capaci tor on the earth connection. You need to suitably insulate anything connect ed to chassis. And running it through an RC filter with R on the -ve may be required to disconect the chassis from mains -ve at rf.
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
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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.
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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.
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.
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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 Pingfuckits 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
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.
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