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ilp archive : journals

public lighting no. 40 vol. 11
January-March 1946

Editorial p9
Cities of Light p9
Mr. Alden W. Welch urges Local Authorities to be more "night light minded", encouraging them to make street lighting a subject of real popular interest. In the enforced "black-out", the lighting of streets has been a matter of general discussion everywhere. It is often controversial: some think it too bright, some think it too dark. But there should be no going backwards by reducing street lighting from any cause whatever. Fuel economy is definitely a matter of grave concern, but it is now urged, for the authorities to keep 'hands off' street lighting as a means of conserving coal. The comparatively small saving from any restrictive measures in Public Lighting is far outweighed by the damage caused by street accidents, increased crime and general public discomfort.
Lighting: Energy, Lighting: Safety

Keep All Lamps Burning p9
Expericent over the past few months have taught some authorities that cutting down of street lighting does not pay. The general desire is for more light. The existing method of cutting out a lamp in odd places is far from satisfactory.
Lighting: Energy, Lighting: Safety

The Next A.P.L.E. Conference p9
It's now 11 years since the A.P.L.E. met in London for a Conference. This year, the first after victory, appears suitable for the Conference to be held in the Capital so the Conference will be in London. The dates are 9th-13th September.
APLE: Conference

Refresher Course In Lighting p9
A series of weekly lectures is being given at the Lighting Service Bureau. It is to bring people up to date with knowledge in the latest development of electric lighting.
Lighting: Education

The City of Tomorrow Night by Alden W. Welch p10
From the American publication "The Magazine Of Light"

For America, the City of Tomorrow i.e. of 1950-1960, will be modern with plenty of automobiles, television, convenient kitchens, more sewage treatment plants "and adequate street lighting." Most progress comes from convincing public spirited citizens that a thing is good for the town. The activating element of this group are the city officials.
Post-war action will be based on three factors: (1) How well America's streets are lit now; (2) When the installations were made and; (3) What improvements in the street light facilities cities now forsee and intend to make after the war.
The American City asked questioned designed to determine the relative importance of these factors and obtained answers from 100 cities. The oldest street lighting system was installed in 1914 in Anderson, Indiana, and an entirely new installation is planned. There were 26 systems installed in the 1920s; 18 between 1930 and 1936; and 38 between 1937 and 1944.
It appears that cities which have made recent improvements evidence greater interest in further inpromovements than do those cities with 1922 to 1927 installations. Individual analysis gave the impression that the improvements projected are more or less matter-of-course and not the result of an awakening to the fact that the upsurge of the automotive era has produced a new concept of street lighting.
How with the influencial group of city officials be made constructively conscious of the necessity of having a modern street lighting system? First having a story and proposal so definite that is will be accepted as Gospel Truth - because it is true and because its acceptance will create a town asset.
Lighting: Future

B.S.I. Specification for Street Lighting by Dr. J. W. T. Walsh p11
Given at the Glasgow Conference on the 12th September 1945.

Summary of the work of the drafting sub-committee responsible for the B.S.I. specification on street lighting to implement the M.O.T. Report of 1937. Copies of the draft specification were distributed at the meeting.

The draft was produced by a sub-committee of five. They were Mr. Elford of Wandsworth and Mr. Colquhoun of Sheffield (Borough Engineers), Mr. F. C. Smith (The Gas Light and Coke Company) and Mr. J. M. Waldram (The General Electric Company Limted) (researchers from the point of view of gas and electricity), and Mr. E. Stroud (President of the Illuminating Engineering Society).

The first attept to devise a specification was made many years ago by a Committee of the Illuminating Engineering Society, one of the members which was A. P. Trotter, who was the doyen of lighting engineering. Some years later the B.S.I. took the matter up and issued B.S.S. No. 307 in 1927 - this was amended and a revised edition issued in 1931. Nothing was said in that specification about the total flux from the lamps or the total flux reaching the roadway.

Some years later the Ministry of Transport appointed a Departmental Committee on Street Lighting. It made a drastic change in the situation because it recommended that all streets should be divided into two classes i.e. a static group called Group A and a non-static group called Group B. It was recommended that for all streets in Group A the mounting height should be a minimum of 25' - this made B.S.S. No. 307 out of date. Classification according to the illumination on the road went by the board and classification was to be entirely according to the nature of the road.

A B.S.I. Committee under the Chairmanshop of Dr. C. C. Paterson pushed on with the preparation of a new specification to implement the M.O.T. Report. Considerable progress was made before the war and a large number of comments were received. The most contentious point was the basis of the specification: was it on a horizontal illumination basis or the illumination on the vertical surface, or the candle power distribution or the distibution from the lamp.

Before the end of hostilities, the main Committee under Dr. Paterson instructed the drafting sub-committee to try and get on with the work again and their first meeting was held in 1944. In the meantime, a very strong opinion had been expressed that it was not desirable to go ahead with the preparation of a standard specification. The view was held that street lighting was not a suitable subject for a specification, and they suggested there should be of Code of Practice setting forth the general aims to be achieved and leaving the designer and user to go as far as possible in the direction pointed out in the Code. It was suggested that the Code might be supplemented by the specification of a street lamp. The position was debated at one very long meeting of the main Committee and it was decided by a quite substantial majority opinion that a specification should be proceeded with.

The various details of the draft specification were then gone through by Dr. Walsh. [These were not included in the summary]

Dr. S. English: What was the acceptance number? It was not regarded as a figure of merit then what was it? He was told it was to ensure the correct fittings were used for any particular installation and that the fittings were correctly installed. He wondered if it would achieve that object. [He showed an example where the wrong fitting gave a better acceptance number than the correct one; and an example where the right fitting incorrectly installed gave a better acceptance number.] No doubt the reply would be that this was not a figure of merit: but the test point illumination of the previous specification was regarded by practically everybody as a figure of merit and was used as such.

Mr. L. P. Minchin (Gas Light and Coke Co.): He agreed with some extent with Dr. English. The chief point he wanted to criticise was due to the 1937 MOT Report. The point was that the light output of lanterns should be on the basis of so many lumens per 100 feet of road. The specification clearly stated the lumen output of the lantern but still referred to the total light output of the lamp, and allowed 30% of the light to go into the upper hemisphere. This meant that two alternative schemes: one of 5,000 lumens per 100 ft. of road (with 30% loss of light to the upper hemisphere); and one of 3,500 lumens per 100 ft. of road (expressing light in the lower hemisphere only) were the same - but the first scheme would be judged better. He felt the figures should be scaled down somewhat and made to refer to the lumens in the lower hemisphere per 100 foot of road. Nevertheless, he felt that this specification, with one or two modifications, would be a very practical bassi for work in the future.

Mr. E. Stroud: The acceptance figure was based on the sum of at least three or four lanterns, with 62% from the first unit and the remainder from the other units. At the request of the Surveyor of Southwick in Sussex, he took tests of a sodium lamp installation put in 1939 but never put into use. He thought it would be a good opportunity to test out this new form of acceptance figure to get a guide for comment on the specification. The roadway was a main coach road with 51 140W sodium lanterns. The posts were 25' high and the overhang from the kerb was about 4', with average spacing of 135'. The acceptance figure should have been 1700 (as per the draft specification) but there was an average acceptance figure of 2400.

Mr. J. M. Waldram (G.E.C.): If people were asked if they would like a specification or a Code of Practice then everybody would say they would like a specification - but a specification for street lighting was not an easy matter. There was the greatest difficulty in getting a specification which was definite and watertight, and at the same time, simple. There were two main sources of energy which had their own specific characteristics and which altered the whole approach to the way the job was carried out. There were also several different natural aspects of light sources which resulted in quite different light distributions. There were also two different types of road laid down by the M.O.T. Report. And there were four parties to the whole affair: the local authority, the people who supplied the energy, the people who did the maintenance and the people who manufacturered the gear. Therefore, it would be appreciated how difficult it was to draft a specification which was simple and watertight and beyond criticism. Therefore it was necessary to take the specification as a whole and see if it was something which was not too bad. Personally he felt they would be bound to have a specification plus a Code of Practice because the nature of the case demanded it and because they could not help themselves.

Mr. F. C. Smith (Gas Light and Coke Company): What was the objective to be achieved? It was to make visible the people who appeared on the roadway and to make the general installation suitable for pedestrians. There had been many attempts to assess an installation from its revealing power but they were very complex and could not be applied in practice. What wwere the factors which determined whether a street lighting installation was good or bad, and what were the variables. They were: (1) mounting height; (2) spacing; (3) Siting of lamps; (4) The distribution characteristics. But, a very important factor not under control of the lighting engineer was the character of the road surface and here it was necessary to have the help and guidance of surveyors. These five factors determined the value of a lighting installation. What was the relationship between the acceptance number and the aim to be achieved? It had a technical background having regard to the difficulties of the situation and it was believed this was the best that could be done at the moment. As for the M.O.T. Report, after many practical assessments, the last word had not been said, but an advance had been made by the M.O.T. Report. There was a link between the acceptance number and the factors which controlled the situation - it had the merit of showing whether an installation came up to a certain standard. The specification enabled the surveyor a great deal of guidance on how an installation should be sited, how the spacing should be arranged and so on. It should also be borne in mind that the specification only applied to Type 1 distribution and to staggered spacing.
Lighting: Specifications

Engineering Principles In Street Lighting Design by J. G. Christopher and J. S. Smith B.Sc. (Eng.) p13
A full reproduction of the conference paper is included.

Dr. S. English: Spoke of the importance of the aesthetic outlook and said he considered this paper, and his own the previous year, to be complementary. There could be really good and well designed lanterns from the mechanical point of view and they could be attractive from the aesthetic point of view. Corrosion in aluminium lanterns was due to electrolytic corrosion which could be prevented by the use of metals which were similar in the electrochemical field. The use of 'horns' to bring in the wires in such a way to leave the water outside was horrible and provision for bringing in the wires should be made an integral part of the lantern.

Mr. W. J. Jones (E.L.M.A.): The Association would be wise to have a paper like this at future conferences, as they were of value not only to engineers but to Councillors. Preventing water dripping on lamps was very important. The general life of the 250 and 400W mercury discharge lamps had increased from 1,500 to 3,000 hours - this halved lamp costs and facilitated and reduced maintenance. The longer life of the lamps renabled re-lamping to take palce before the bad weather came on, and the lamps would last until the return of fine weather in May or June. This Conference would go down in the annals of the A.P.L.E. as the one where a remarkable new range of clean, new designs were shown at the Exhibition, not only as regards lanterns, but in the attempts to deal with street lighting furniure as a whole. These clean designs got rid of some of the Victorian 'pub' brackets. He urged that Councillors should take a keen interest in the clean or architectural design of street lighting furniture.

Mr. J. F. Colquhoun (Lighting Engineer, Sheffield): Urged the need for the greatest co-operation between lamp fittings designers and makers, and the users. Very often the people who had to maintain the fittings were presented with some weird contraptions which involved the use of little bolts and nuts at considerable height in bad weather. Perhaps the B.S.I. was the most appropiate body to deal with this matter?

Mr. E. Gardner Thorpe (Borough Engineer, Slough) Would mercury vapour lamps be available in sizes below 80W in the near future? They would be very suitable for side street lighting. Could the control gear be turned out as a complete unit ready to be fixed to the board in the base of the pole where it would be much more protected from condensation and moisture - and only four terminals would be necessary. Also, what developments in small gas lanterns for side street work be expected? Pre-war lanterns had various snags: the light source was too large for optical control, the light control was poor and the optical systems were crude; and frequent attention was needed for the cleaning of burners.
Mr. G. E. Hill (Borough Engineer, Gravesend: The electric lamps in his area remained in-situ during the war, but were not used. They were of clean design and when taken down and examined less than 10% showed any serious defect and in that 10% the defect was the anodised aluminium reflectors.

Mr. E. C. Lennox (North Eastern Electricity Supply Co.): Expressed the hope that larger bolts and nuts would be continued in preference to a large number of small bolts and nuts which, on a high pole, were a great trouble to maintain. He was also pleased to see side entry and wondered why this hadn't been done before.

Mr. Smyth: He expressed agreement to the need of co-operation among designers and users of street lighting fittings. He was not sufficiently familiar with the machinery of the B.S.I. to whether it was the appropriate body. He thoroughly disiked top entry of wires into the lanterns. The suggestion that control gear be a separate unit was an excellent one. He did not know whether a mercury vapour lamp below 80W was on the stocks.
Lighting: Design, Lighting: Luminaires, Lighting: Maintenance, Lighting: Materials

The Commercial Aspect of Street Lighting by E. S. Harris (Public Lighting Superintendent, The Gas Light and Coke Company p21
A full reproduction of the conference paper is included.

Mr. H. W. Lodge (Lighting Engineer, Halifax): In the old days, there was only gas for street lighting, and now electricity was expected to take a fair share. Electricity was being dealt with along the right lines, for there was a specification for the rate of flow of energy compared with the candle power of the lamps for each fitting. As a lighting engineer, he was still waiting patiently for the gas industry to come forward with a similar specification for different sized mantles. 70% of the street lamps in London were gas, and he asked the gas industry and the manufacturers to work together to give a burner which had a known value. He asked for a gas burner with an attachment in the form of a constant pressure governor with a fixed nipple and a fixed air supply. If the gas industry then gave a pressure which was above the minimum, the lighting engineer could reduce to give a standard calorific value. In that way the lighting engineer would be saved arguing with the gas engineer as to the rate of flow per burner.

Mr. Crawford Sugg said that prior to the war, gas manufacturers had developed fittings for side streets which entirely departed from the traditional rectangular lantern. These fittings were not just merely different in design and shape; they made a serious attempt to overcome the disabilities, particularly with regard to maintenance. The result was that the reflectors and re-directing devices employed were totally modern in conception and each lamp repeated the performance of the prototype. The burner used a nipple which passed a fixed amount of gas in conjunction with a constant pressure governor. The design had been so simplified that in some cases the whole burner could be stripped and put together again without in any way imparing the adjustment. There had been a radical breaking away from the sheet metal age in their construction.

Mr E. C. Lennox (North Eastern Electric Supply Company) thought the title of the paper was misleading as it dealt solely with gas whereas equally good service was available from electric supply authorities. The paper was also misleading in the paragraph listing popular streets lit by gas - there were many similar installations which gave good lighting by other means. There were also references to new contracts by gas lighting, when there had been many by electric lighting. However, the paper was a valuable contribution because it showed to lighting authorities what could be otained from a public company. There were many lighting authorities in the country which did not have their own lighting departments but could obtain the services from such companies as that of the author. The 'excessive lighting' of main roads was referring to lighting of a particular type which was fashionable in some quarters but if he intended to suggest it was wasteful of fuel then he was quite wrong. The figures of fuel consumption for gas and electricity per lumen output was 1 unit of fuel for electricity to 6 units for gas and in the case of side street lighting there was 20 times the fuel consumption for coal for gas as compared with electricity for the same light output. Therefore the excessive electric street lighting cost less.

Mr. L. P. Minchin (Gas Light and Coke Co.) referred to the table relating road surface to light distribution adn suggested this was suomething upon which there might well be collaboration. The Draft British Standard Specification described three types of distribution, but only dealt with Type 1, which had the light emitted at a high angle - about 80°. The next thing to know was where these types of distribution should be used, and some sort of schedule or code of practice would have to be devised to tell people under what conditions these different types should be used. The table was a very tentative beginning. Many roads were far from straight and having the light at a high angle was very small.

Mr. F. C. Smith (Gas Light and Coke Co.) stated that the street lighting specification was for the lighting of streets (not just by electricity) - it was a joint effort with the gas industry. Secondly, there would shortly be received from the British Standards Institution another specification in which the gas burner was specified.

Mr. Harris His company was very keen on governors and fixed nipples and something definite would be done in that matter. He had not intended to imply that good service was not rendered by electricity with regard to street lighting.
Lighting: Comparisons, Lighting: Distribution, Lighting: Energy, Lighting: Luminaires, Lighting: Management, Lighting: Specifications, Lighting: Theory

Closing Words At The Conference p25
A suggestion was made for the Conference to be held in Paris in 1947.
Votes of thanks.
APLE: Conference

Correspondence p26
Further discussion of the "acceptance number" in the draft British Standards Specification. Letters from L. T. Minchin and E. Stroud (BLEECO)
Lighting: Specifications

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