Oops, it looks as though I goofed a little -- Sorry! I was working from memory, and it's several months ago I read the book. Anyway, the 5-wire wasn't right back to the generating station but just within each building, and it was in Vienna, not London.

I like my humble pie served nice and warm please..... [Linked Image]

Anyway, here's the appropriate section, from the book "R.E.B. Crompton, Pioneer Electrical Engineer," HMSO 1969:

{Quote]

Crompton spent much of the years 1885 to 1889 in Vienna lighting the Opera House, theatres and public buildings. The Ring Theatre, previously lit by gas, was destroyed by fire in 1883 with great loss of life. Emperor Franz Joseph decided that, for greater safety, electric lighting should be introduced. The Imperial and Continental Gas Company, who retained the contract for lighting the theatres, engaged Crompton to design and supervise the work and to manufacture some of the equipment.

A single central generating station supplied all the buildings, which were up to one mile away - a far more widespread system than any previously attempted anywhere in the world.

The highest voltage filament lamps then available required 100 volts. To obtain the advantages of high-voltage distribution (lower current and therefore cheaper cables) he devised the 'five-wire system' of supply with batteries at each load point (figure 20). The generating station operated at about 440 volts d.c. and charged a Crompton-Howell battery of 200 cells at each theatre or other consumer. The theatre lighting was divided between four circuits each supplied at 100 volts from one quarter of the battery. In the generating station six Willans 150 horsepower steam engines were each directly coupled to a Crompton generator. The generating capacity was over 700 kilowatts, and for special effects at the Opera 1000 kilowatts could be utilised, with the batteries discharging at their maximum rate.

The Opera House was the first large theatre to be lighted electrically. Bracket lamps were put on the fronts of the balconies and boxes, which was impossible with gas lighting because of the rising fumes and hot air. On the stage Crompton introduced coloured lights, separately controlled by resistance dimmers in which resistance coils were short-circuited by being lowered into a vessel of mercury. Several operas and ballets were put on to test the scenic possibilities, and Viennese society flocked to see what could be done with the 'electric gas.'

[End quote]

* Fig. 20 shows a 2-w supply to each bldg. to four series-connected 100V batteries, and a 5-w distribution from batteries to lights.