Heidelberg Historical Society

Electric Light Scheme for Heidelberg, 1914.

Substantial technical detail was made public when Heidelberg's electricity supply was being planned. Perhaps Heidelberg (or "Banyule") citizens would not see so much information in the press today. Perhaps they would not want to read it. Here is a detailed article on a projected electric light scheme for the shire. Note that Fairfield was a significant centre within the municipality in 1914.

ELECTRIC LIGHT SCHEME. SECOND EXPERT'S REPORT.
ADOPTED BY HEIDELBERG COUNCIL—LOAN OF £10,000 TO BE EXPENDED.

Published in Heidelberg News and Greensborough and Diamond Creek Chronicle, Saturday 3 January 1914. Acknowledgement to TROVE and the State Library of Victoria. Acknowledgement to Museum Victoria for photograph.

Sub Stations,—Under this present scheme four brick sub-stations were provided for. These will be small structures of good appearance placed in the streets, or reserves, in suitable situations. To these sub-stations the high tension mains will run to supply the transformers housed in them. These transformers will be of size and number suitable for the load to be supplied in the particular locality in which they are situated. The pressure, will, by means of these transformers be converted from the 4000 volts primary to the 300-400 volts secondary, which will be the voltage supplied to the low tension network from which the current for the consumers will be drawn.

Street Lighting.—Without making a thorough and detailed survey of the shire, and actually designing the complete secondary network and fixing the electric street lamps at suitable positions on this network, it is only possible to approximate the number of these lamps required.

If the work was proceeded with, he suggested having them where electric cables for supplying ordinary consumers are convenient, and gas lamps in the street where gas mains and not electric are laid. Where there is neither of the supplies he suggested connecting whichever one is the more easily and economically available. For the electric street lighting he allowed for 200 brackets, each fitted with two lamps. The reason for having two lamps at each lighting point is that one lamp may be switched off automatically at, say, eleven o'clock or midnight, and the other at, say, one o'clock, or day- light, or whatever times the council so decides. These automtic switches will be placed in the substations, each controlling the particular area in which situated. This arrangement does not involve a great deal of extra cost, and if it is desirable to have lights burning all night, as in some municipalities, it can be done with smaller lamps after, say, eleven o'clock and so economise current. He designed this arrangement recently for a country town lighting scheme and it works admirably and efficiently.

Low Tension Network.—This will be entirely of bare copper cables on poles. The sub-stations will each act as centres of supply from which these low tension or secondary mains will radiate. The system of distribution will be three wire 200-400 volts.

Cost of Installation.—In going into this important feature of the undertaking, he provided for the primary mains to be placed underground in parts where they would become a hazard if placed on poles, and on poles where they could be so placed with safety such as along streets sparsely populated. As such places became settled upon, then can the mains be placed underground. By placing some on poles now will relieve the first burden of cost materially, and he estimated upon half the primary mains being underground. Upon this point he had the concurrence of Mr. Chambers, electric inspector to the Public Works Department. The size of main cables, transformers etc., is fixed by what will be the load in two years plus 100 per centum. From experience gained in other districts similar to Heidelberg, he is of the opinion that the number of consumers in two years will be 550. The average maximum load of each customer will be approximately .174 kilo watts. Therefore, the total maximum load of 550 consumers will be 96 kilo watts. Add to this the current consumed by the 200 street brackets, each taking 100 watts, and the average working load will be 116 kilo watts. In making my calculations I have not taken into consideration more than in a usual way the motor load that is likely to come on, this branch of the supply being regarded as small, compared with the lighting. As at least 90 per cent. of a motor load runs only in the day time, when practically no lighting is being used, the system will carry over 200 horse power without any additional expenditure. His estimate of the work is as follows:— (1) 3 Miles high tension underground cable laid in wooden troughs, £1890; (2) 3 Miles high tension overhead cable on poles complete with 120 poles, insulators, arms, cradles etc., £860; (3) 20 miles low tension net- work with 800 poles, 60 miles copper cable, insulators, sectional fuses, etc., £3192; (4) 550 services, meters, service fuses, etc., £1940; (5) 4 sub-stations, 1 measuring station, with buildings and complete equipment for 232 kilo watts, 1500; (6) 600 street brackets each for two lamps with all wire, cable, insulators, automatic time switches, fuses etc., £975

(7) legal and other expenses and contingencies, say £200—making a total of £10,557. By providing the high tension network for three sub-stations, reducing the secondary network to 15 miles, the number of consumers to 400 and the sub-stations to 3 instead of four, the total cost of the work would be £8700. He was of opinion that the price of current should be 3d per unit for power and heating, and 6d per unit for lighting.

Revenue.—He estimated the revenue at the end of two years to be as follows:—550 consumers each using, say, .75 units per day—273 units per year; total consumption. 150,150 units per year; 150,150 units at 6d. £3753; meter rent, 550 meters at 6s. per annum, £165; total, £3818.

Mr. Clements, manager of the Melbourne Electrical Supply Co., has informed him that the company's charge for selling current in bulk is 10 6 Kilo Watt of maximum demand and ¾d. per unit of current consumed. The demand indicator to be set every month. The expenditure per annum therefore will be:—Purchase of current: 116 kilo watt maximum demand, plus 15 per cent for conversion and transmission losses—132 kilo watts, at 10/10 per month per annum, £852; 150.150 unit plus 15 per cent. for conversion and transmission losses. 172,672 units at ¾d per unit per annum. £539; total, £1391. Labor—Clerk £150; meter reader, £150; outside foreman, £208; assistant foreman, £104; total, £612.

Capital charges—5 per cent on £10,557, £527; Depreciation—5 per cent on poles £1380 £69; 5 per cent on buildings £500, £25; 5 per cent on equipment, £1000, £50; 10 per cent on meters, £1100, £110; total, £254; grand total, £3634.

As will be noticed, he had not included in the above statement any revenue derived from the street lighting, although it is included in the purchase of current, assuming that the council merely makes this a book entry and credits the electric supply department with the current consumed by each of these street lighting points burning, 100 watts for four hours and 25 watts for three hours per night for 250 nights per annum, then the amount credited at 6d per unit would be £625, making the total credit balance derived from the undertaking £909. In conclusion he desired he desired to state that he had treated the subject in a general way.

Owing to many of his figures having been actually realised in other parts of the metropolitan area, whilst others, such as, cost and erection of poles, cables, street brackets, are actually contract prices of some work he was doing in one of the country towns in Victoria, they are as accurate as it is possible to get them, although, of course, conditions are slightly altered. Taking the load of the consumers at .174 kilo watts, as he had done, will be on the low side, and it will be found that with the various large hospitals using the light, that this average consumption will be higher, so improving the revenue."

We do not know if Heidelberg is a municipality where "it is desirable to have lights burning all night," and if so, what is supposed to happen "after, say, 11 o'clock" that the "smaller lamps" might reveal to the proper authorities. See, for example, *this link*.

Interesting too is the expectation that most wires would be placed underground, except "in streets sparsely populated". Clearly most private streets now have overhead wires, except in some recent developments. Unfortunate.

Historical Scraps