Voltage standardisation

[G6Tanuki]

Originally Posted by Richard_FM

Some early supplies seemed to be for industrial purposes & later used for housing in the area, even if it was non-standard

Yes, in industrial/mining/mill areas it was quite normal for the local coal-pit/steel-mill to supply electricity to the workers' houses, just as they'd given workers a 'coal allowance' [which workers often had to haul from the pithead] to heat their company-homes.

The voltage/frequency was distinctly local.

[hannahs radios]

A friend of my uncle's lived in Lambeth, the mains there was 100 Volts AC frequency not known. He had portable transformers all round his house to bring the voltage up to 240V for use by regular appliances. Of course lighting was by 100 Volt lamps.

[broadgage]

Originally Posted by hannahs radios

Heatercathodeshort re 440 Volts supply don't forget that 440V between phases would give 255V phase to earth so would have been suitable for domestic use. Even these days your local transformer gives 433 Volts phase to phase and 250 phase to neutral, so really not much has changed.

True, but it was reported as being 25 cycles, which is to low for domestic lighting. Lamp flicker would be obtrusive and unpleasant and would be particularly bad on the very low current lamps used domestically.

In the case of factories with a low frequency supply for machinery, lighting was achieved in various ways.
Retain gas lighting, zero capital cost if already existing.
Obtain a seperate DC lighting supply, either from DC mains or from a rotary converter.
Use very low voltage lamps such as 6 volt 36 watt vehicle lamps from transformers.
Use low voltage, high power lamps in series, such as 50 volt, 300 watt.

For very small scale localised lighting on a machine, a bicycle dynamo could be belt driven from some moving part of the machine, and light a 6 volt 3 watt cycle headlight bulb.
3 watts sounds paltry by todays standards but gave more light than a candle and could be placed and directed exactly where needed, unlike a candle and with negligable fire risk.

Also of course the 440 volt 3 phase supply might have been 3 phase, 3 wire, without a neutral. Several different systems existed including;
3 phase, 4 wire at the generator or transformer but with the neutral not distributed.
3 phase, 3 wire, floating with regard to earth. This had the advantage that any single earth fault would not disable the system.
3 phase, 3 wire, delta with one phase earthed. This had the advantage that only 2 wires needed switches or fuses rather than all 3.

All the above are still used today for special purposes, but not AFAIK for UK public supplies.

[hannahs radios]

The UK public supply is standard 4 wire on the LV side in the USA they use the 1 phase grounded arrangement think they call it high leg or something like that and yes the all 3 lines floating is used its called an IT system it's not allowed on public mains but some special private supplies use it though don't know what for.

[David Simpson]

Scott, regards the pre-privatisation records of SSEB/NOSHEB - right enough, we were all employed by the Scottish Office. So maybe some records are held at "New Register House" in Edinburgh. Just off Princess St behind Waverly Station. If they don't hold Scottish Office records, they would certainly put you on to whoever does.
Which Utility now supplies the former SSEB area ?

Regards, David

[Heatercathodeshort]

Hello BG,
Re post 16. I think you miss read it. The voltage listed was 1250v. J.

[broadgage]

Originally Posted by Heatercathodeshort

Hello BG,
Re post 16. I think you miss read it. The voltage listed was 1250v. J.

I was referring to post #4 in which a 6,500 volt DC supply is mentioned.
1,250 volts is indeed more reasonable for series arc circuits.

[broadgage]

Originally Posted by hannahs radios

The UK public supply is standard 4 wire on the LV side in the USA they use the 1 phase grounded arrangement think they call it high leg or something like that and yes the all 3 lines floating is used its called an IT system its not allowed on public mains but some special private supplys use it though dont know what for

Two different systems exist in the USA.
3 wire, 3 phase with one phase grounded, known as "corner grounded delta"

Also 3 phase, 4 wire, delta. Known as "high leg delta" this uses 3 single phase transformers with 240 volt secondaries delta connected.
One transformer has an earthed center tap which forms the neutral. This is the bottom winding as usually drawn.
Any phase to any other=240 volts.
Neutral to either of the "bottom" phases=120 volts.
Neutral to the "high phase" =208 volts.

[Croozer]

Scott37 - this is from memory and I don't have references - but I think that pre nationalisation much of Glasgow was supplied by the corporation - in particular the city centre was from the PS at Port Dundas, however I don't think the corporation had exclusivity. I think they had competition from The Clyde Valley company. On the other side of the country, Edinburgh was supplied by the corporation - despite my flat being wired in 1950 (after nationalisation) all of the hardware in the close is stamped Edinburgh corporation electricity supply, and the meter card is issued by the corporation rather than the then south east Scotland electricity board.

[hannahs radios]

Broadgage, thanks for that. I think I got my facts a little muddled. Despite the USA being the most technically advanced country theie electrical system is a real mess so many different systems, at least domestic supplies are standardized, that's one good thing.

[Scott37]

Croozer - thanks for this info. I'm going away for a few days but when I get back I will investigate further. I'll try Google more creatively, visit the Mitchell Library and speak to my friend recently retired from Scottish Power. We also have a local historian (who wrote a book), so I can contact her also.