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ilp archive : journals

public lighting no. 19 vol. 5
October 1940

Editorial p73
Street Lighting During Air Raids
The installation of "star light" street lighting, which was proceeding steadily until about the end of August, has stopped. There is a disinclination to go ahead with schemes, and in some areas the lighting has been turned off - either intentionally by the Local Authority or maliciously by the public. The fear is that the lighting attracts enemy bombers and the action taken by the Local Authority has been in deference to public opinion.
If bombs fall on, or near, a lighted street, the uninformed layman may think that the street lighting is to blame. But there is no evidence that the ligthing is an aid to objective bombing. It is up to each Local Authority to decide for itself whether it will pander to the uniformed public opinion, or whether it will maintain this great public amenity and endeavour to educate the public.
The argument is that if the Ministry Of Home Security consider the installation of war-time street ligthing within 12 miles of the coast dangerous, then why should the lighting be any less dangerous in other parts of the country? The fact is that enemy bombers flying low over the sea might be able to see the coast thanks to the contrast between the blackness of the sea and the street lighting. It is the height which is key: at higher flying heights, the lighting is invisible. This is the probable reason.
Instances have occurred where lighting fittings, installed on a roadway on a hill, can be seen fron a considerible distance, perhaps several miles, at lower altitude. The public consequently can't believe that an enemy airmain cannot also see the lights from a distance. The lighting fittings are specially designed and rigidly tested to ensure that no direct light is emitted at angles 5° ablove the horizontal. Therefore light from the fitting may be seen at the bottom of the hill, but won't be seen from above. The writer has demonstated this several times to his neighbours, who have expressed alarm at the existance of a lighting fitting in their immediate vicinity. The fitting is mounted at 12' but from a first floor window it is quite invisible.
Householders often remark: "If we showed a light liek that from our windows we would soon get a visit from an air raid warden or a summons from the police. Why are these street lights allowed to remain alight during an air raid?" There are two answers: (1) Owing to the design of the fitting, no direct light is visible from above, wherease the light from a window could be seen from a considerable height; (2) street lighting uses a 15 or 25W lamp and only 5% of the light emerges from the fitting. The light from a window is probably due to a 100W lamp which is not shielded to the same extent. Consequently, the intensity of a chink of light from a winder may be considerably greater than the beams from a street lighting fitting. Even if this light from the window is not visible from above, it may light up the roadway or buildings opposite, to a much greater intenstiy than would a street lighting fitting.
The use of motor-car headlamps also frequently gives rise to comment. Headlamps must be extinguished on receipt of a "purple" warning. Why should street lamps be allowed to remain in operation. The headlamp masks are specially designed to prevent emission of light above the horizontal, and so it may be argued that it's no more dangerous than the street light. However, (1) many headlight masks are improperly adjusted with light emitted above the horizontal; (2) even if the headlight is properly adjusted, direct light may be emitted upwards when the vehicle is ascending a steep hill; (3) the patch of light on the road is enormously brighter than the illumination due to the street lighting.
As far as the official attribute towards street lighting is concerned, no indication of a change of policy has been given. This is qualified by a reminder that the Prime Minister in his speech in the House Of Commons on September 5th referred to "this business of lighting the streets." He expressed the hope that we were not going through all the gloomy business that we went through last year and he had set up a committee: "To see in what way we can make more light and cheer in the winter months, and at the same time subserve the purposes of alert and alarm."
It is possible that some Local Authorities are holding their hand until a further official pronoucement is made, but the official policy will probably be towards more light, not less. However, the fact remains that the present standard represents what the Ministry considers the maximum safe illumination from the point of view of visibility from the air. (Whilst these two statements may be contradictory, keep in mind that the present standard is intended to keep the lighting on during air raids. Any additional lighting would probably be treated in the same way as the lighting at railway sidings - the lighting here is substantially higher than street lighting, but is extinguished on recipt of a "purple" warning.
Whether any higher standard of street lgihting is permitted in London and other large towns subjected to almost continuous aerial bombardment remains to be seen.
Lighting: ARP

Wartime Street Lighting Cannot Be Seen In The Black-Out p74
From a letter sent by J. F. Colquhoun, Lighting Engineer of Sheffield: "I have now 25,000 street lamps in use in Sheffield. Aeriel observations were taken on the 8th, 9th and 10th October, and I have now received a copy of the Flight Lieutenant's report: 'Street lighting at Sheffield was extremely well blacked out, and great care must have been taken, as I was unable to observe an illumination from this cause.'"
Lighting: ARP

Air Raid Shelter Lighting p74
Now that Air Raid Shelters are being occupied for lengthy periods, the matter of safe lighting becomes of great importance. Crompton Parkinson Ltd in association with The British Electric Transformer Company Ltd offer low voltage lighting units. These units are designed and manufactured to BSS/794 (for indoor use in a fixed location) and are particularly suitable for shelter lighting as stipulated in BS/ARP 6 and BS/ARP 20. The lighting unit consists of a double-wound air-cooled transformer, a double-pole supply switch, double pole re-wirable supply fuses and a single pole cartridge fuse. This apparatus is contained in a two-part cast-iron case with hinged front, the switch handle being interlocked with the case in such a manner as to prevent the opening of the case when the switch is in the "ON" positon. The cast-iron case is arranged for conduit entry for the supply of the bottom. Conduit exists for the low voltage leads are porvided at the top and bottom of the case. The unit is designed to accommodate transformers of 50, 75, 100, 150 or 250 VA, but it is possible under certain conditions to design suitable transformers up to 500 VA. The standard secondary voltage should be 12, 25, 32 or 50V. For units in accordance with BS/ARP 6, the standard transformer output for lighting purposes is 150VA and the secondary voltage is 12V at half-load, unity power factor 15°.
Lighting: ARP

The "Portsmouth" Blended Lighting Unit p74
Seeing that lighting by electric discharge lamps has now taken a foremost place in modern illumination practice, Lighting Engineers will be intereted in the Crompton Portsmouth Blended Lighting Unit. Being of the omni-choke type, ensures a satisfactory blending of mercury and tunsten filament lighting, affording illumination with remarkably good colour characteristics, and has successfully solved the problem of providing this kind of lighting for various applications.
Lighting: Other

The Lighting Of Road Obstructions by H. H. Ballin, B.Sc. (Econ.) and W. F. S. Debenham (Members of the Exterior Lighting Department of the GEC) p75
In the times of peace-time streetlighting, the task of the illuminating engineer was to provide an adequate degree of even brightness over the road surface for the benefit of all users of the public highway. The lighting now permitted under black-out conditions, with an illumination of about 1/1000th of the peace-time values, serves the purpose of assisting the pedestrian, and creates an amenity value doubly welcome during air raids, when torches must be extinguished. The motorist derives practically no assistance from "Starlighting" and is entirely dependent on his severly obscured headlight and sidelights. It is extremely difficult for him to notice obstacles in the road, especially as the masked headlight may have to be extinguished when raiders are overhead, and the side lights now permitted are insufficient as driving lights. As surface shelters are being erected everywhere, neither street nor car ligths are sufficiently strong.
Legislative Position: The installation of warning lights is governed by the Lighting (Restrictions) Order 1940, Part II. However Clause 3 of Part I makes it lawful for the chief officer of the police to authorise the display of other lights - a number of new developments have taken place by this clause. Recently the London Regional Technical Advisers Branch of the Air Raid Precautiosn Department of the Ministry Of Home Security have issued a Memorandium where recommendations were made for the lighting of surface shelters, but many local authorities, with the approval of the police, have designed their own warning lights.
General Symbols: It is important to distingush between two types of obstructions: those dividing the road into two separate lanes with one-way traffic (i.e. pedestrian refuge/centre island/roundabout), and those which narrow the roadway. In accordance with Clause 6 (d) of the Lighting order, the warning light for the first case must be a white St. Andrew's Cross. (These effectively replace "Keep Left" signs). The driver is entitled to assume that he passes these signs on the right. On islands which don't have one-way traffic around them, red lights of no particular shape are used. Any symbol can be used but specical care must be taken to prevent them from looking like the rear lights of stationary cars. For shelters, red arrows have been suggested - the purpose of such arrows is to warn traffic to drive to the right or left.
Intensties: Any increase in the intensity of warning lights above that necessary for their legiblity not only impairs the black-out but defeats its own object by creating glare and thus hindering visibility. The permitted candle power of red warning lights is 1 candle - which is quite high - and 0.013 candle power would be more suitable. As warning lights are not placed at regular intervals, there is less danger of light patterns being formed which could be read from the air, but a cluster of such lights may indicate an important junction to the enemy. The majority of surface shelters are not erected in roads with a great deal of fast moving traffic and red shelter warning lights need not be as bright as other traffic warning lights. It is therefore possible to go well below the maximum values.
Warning Lights On Surface Shelters: The recommendations regarding the installation of warning lights on surface shelters are based on the lighting of road obstructions. All units should be erected at a height of 3'6" to give maximum visibility to road users. (Those at ground level cannot be seen from certain types of cars and reflect a high proportion of light up into the air. Those mounted too high are screened by the projecting hoods of cars.)
Shelters On The Side Of Roads: If a shelter is entirely on the footpath, it forms no obstacle for traffic, and the Memorandum of the Ministry of Home Security makes no suggestion as to its lighting. It is felt advisable to provide a red warning light for pedestrians although "Starlight" street ligthing will help. if a shelter extends into the roadway, it is necessary to indicate it by a red light on the outer edge. If it takes the form of a red arrow leading the traffic past the shelter then it will be of additional assistance. If a shelter protrudes more than 6', a furtehr warning light, preferably a red arrow pointing away from the footpath, should be erected over the kerb edge. Red lights at right handles to the traffic flow on the outer corners are useful for indicating the obstruction to pedestrians across the road - these are optional. If the shelter is more than 50' long, additional red warning lights are specified for every 50' of length.
Shelters In The Centre Of Roads: When shelters are in the centre of roadways dividing the traffic into two opposing streams, the St. Andrew's Cross sign, is essential for the left-hand corner. If the shelter exceeds 10', then different units are required, namely a St. Andrews Cross on the left, a red warning light on the right, and an additional red unit midway.
Characteristics Of The Warning Lights: The type of unit is not closely specified. As the light is mounted at 3'6", then it's advisable to have it recessed into the shelter wall whenever possible. Other factors to be watched are mechanical strengh, assurance of correct light output, ease of erection and maintenance. Thin glass panels are not suitable for shelter warning lights unless the limitation of the light output is independent of them (with metal screens or baffles). Otherwise, if the glass was shattered by a blast, light of excessive brightness would be emitted and would be such a menace as to necessitate swiching off. Wired glass is preferable. The choice of materials is governed by the conditions of supply: fittings have to be designed with the minimum of metal. A weatherproof sheet steel box unit, taking the place of one brick only, has been designed to meet these requirements. As for supply, some shelters have been equipped with batteries and/or step-down transformers: one unit has been designed for use with 24V 6W bus lamps running off a 12V supply so the consumption is 2W. Where mains supplies are available 15W sign type lights are recommended, the supply being taken from neighbouring street lights using overhead wires, and the timeswitch could be used.
Lighting: ARP, Lighting: Luminaries

War Lighting Difficulties by E. J. Stewart, M.A., B.Sc. (President Association of Public Lighting Engineers) p77
When agreement had been reached on a safe means of street lighting, there was some excessive optimism about the rate of installation throughout the country. Slowness was due: to the tendency of many authorities to give only small trial orders and wait for the beginning of next winter "to see how things were going"; and on delays obtaining fittings ordered. This was caused partly by the rush of orders from various towns at the same time, partly by the time required for approval, due to the makers' difficulty in obtaining material and due to slow transport.
Some towns arranged to light central streets or all main routes, and in some cities such as Sheffield and Bristol, the Council approved the ARP lighting of all of the streets at an early date so could get big orders and get quick delivery. Generally police and drivers, as well as pedestrians, have expressed appreciation of the lighting on really dark nights. The only question is how much one is prepared to pay for the comfort and safety.
Some towns which normally extinguish in summer darkened their ARP lighting for that period without question, or delayed to light until after summer; but some all-the-year-round towns decided that 0.0002fc could not compete with most June nights lit by sky, moon or star.
There hass been no general shortage of gas or electricity. Prices have risen but in some areas not so seriously as feared.
As regards finance, 1939-1940 was a year of loss for gas and electricity undertakings by drop in the sale for street lighting; and for the same reason there were large savings on the expenditure of Lighting Departments. The Government, after its hesitation, gave not merely its sanction but its blessing to star-lighting and offered loan-terms for purchase of fittings; but the cost is still on local authorities and some still fear that they will be left with an installation and no staff to maintain it.
There have been no shortage in mantles or lamps, but glass offers difficulty. Uniforms will have to last longer. Officials needing metals or timber know about priority and certificates and triplicates. The lighting of shelters and dangers in out-of-the-way places has raised problems in supply of gas or electricity. Some Departments have learned how oil lamps burn.
The effect of shortage of labour was not felt in last winter or spring. Not it is serious where lighting activities are going on. As was expected the calling away of men has become more irresistible. Lamplighters, and other "unskilled" maintenance men are not only being called to the Amry but released, in the national interest, for wok at the skilled trades from which they came in years of depression. Desirable and life-saving as is street lighting, in the last resort the nation can exist without it, but not without aeroplanes. Some departments have already started women as lamplighters, others are considering.
Decision not to light as all has not removed all problems. Many lighting authorities have been at variance with their suppliers of gas and electricity. Lighting engineers, as well as tradesmen and lamplighters, went to ARP duties under teh same local authority. There is also preparation to defend premises and plant against damage or interference in the case of air raid or invasion. We have been constructing shelters, aquiring steel helments for our repair squads, training in first aid and bomb disposal.
Where erection and maintenance of street lighting is quiet, some departments would gladly use the opportunity to overhaul plant, to paint and preserve, to extend central control apparatus. But the scarcity of men has hindered these works. Renewals and cleaning previously done at night have had to be concentrated into daylight.
Lighting Departments with experimental sections have had to almost abandon work on the the "improvement" of lighting. At the same time there has been abundant work for them in the adaptation of lighting to war conditions.
Two or three years ahead, by the second official estimate, lie the lighting problems of the Second Great Peace: (1) The problems of labour; (2) The more personal problems of the men who come back and the men who don't' (3) The problems of material and cost and, once again, of everyone wanting everything at the same time; (4) the problems of the revised Street Lighting Specification and no ARP about it.
Lighting: ARP, Lighting: Funding, Lighting: Management , Lighting: Users

A Small Lamp For Illuminating Fluorescent Signs p78
Of lamps that have come into prominence during the war, the Philips 5W argon must be considered the most important. It is not new, but in peace-time its uses were strictly limited. When war came, its great versatility for lighting shop windows and directional signs became apparent.
It provides a host of practical new applications for fluorescent effects with ultra-violet radiation which were not practical in the past. The points that commend the new lamp are:
(1) Its small size (85mm long x 45 mm diameter)
(2) Its low emission of ultra-violet rays which can be used to excite useful fluorescene at at a distance of 2" to 12".
(3) It can be plugged direct into the mains without condensers or transformer.
(4) It has no filament, the internal construction being the same as the 5W neon with spiral electrodes. This means immunity to vibration - very important when used in bollards. The generation of heat is practically nil - antoher important point when being used in a confined or enclosed space.
It will find a use for low illumination in shelters, entrances, bollards, street signs etc.
Bollards: Paint the message on the glass in fluorescent paint and then black out around the lettering. The lamp is then placed inside the bollard, so that the message fluoresces from inside and gives excellent definition without undue brilliance.
Directional Signs: All manner of street signs such as ARP directions, police and telephone boxes, traffic directions etc., can be treated with fluorescent paint and irradiated from the front by the 5W Argon lamp in a trough above or below the sign.
Lighting: ARP, Lighting: Lamps

Holophane Illumination Gauge p79
Details of the gauge which has been made in accordance with the draft Specification BS/ARP 30 for measuring values of 0.2 to 0.001 foot candles.
Lighting: ARP, Lighting: Equipment

Signs For Wartime p79
Details of an illustrated booklet by Gowshall Ltd which sets out all types of road signs and road lamps.
Lighting: ARP, Lighting: Signs

High Standard Bridge Lighting In India p80
Details of an installation on the Jamalpur Bridge, Ahmedabad in India. Directional Difractor lanterns mounted at 25' on steel columns were installed. A staggered arrangements with 250W Osira high pressure mercury lamps were used, spaced at 140' apart. The lamps and auxiliary gear were provided by the GEC.
Lighting: Installations, Lighting: Luminaries

The Late Mr. Thoams Roles p80
Obituary of Thomas Roles who was City Electrical Engineer and Manager of the Bradford Corporation.
Lighting: Personnel

17th Annual General Meeting Of The APLE p80
Details of the Annual General Meeting to be held at St. Ermin's Hotel, Westminster on the 21st November. At 2:30PM a general meeting was held for dicussing various difficulties that presented themselves during the war. Also the APLE has moved to a new address at 68 Victoria Street, London.
APLE: Organisation

A Method Of Illuminating Street Signs And Bollards Under Black-Out Conditions by R. C. Bicknell p81
The Air Raid Precautions Department of the Home Office in Memorandum On Aids To The Movement Of Traffic To Be Installed In Roads And Streets In The Absence of Street Lighting has defined clearly the measures to be adopted for screening upward rays from certain types of signal and sign.
However, the lighting of warning and obstruction signs to the low order of intensity called for in the above-mentioned memorandum presents certain difficulties. This method has been developed after extensive experimental work by Siemens Lighting Engineers working with officials of an important Borough Council.
The requirements are: (1) The signs be legible to drivers at 100' (2) Be inconspicuous at 250' (3) Brightness of the letters to be reduced to 0.1 candles per square foot (4) Colour of light must be white.
Therefore must use incandescent lamps, and the one with the loweset consumption is the 15W Pearl Lamp. This gives 118 lumens, or 9 mean spherical candle power, which must be reduced very considerably by absorption or ther means if to be used. There are objections to absorbing the excess light by overall spraying of the lamp bulb - it reduces heat dissipation, shortens the life of the lamp, and many also distort the colour of the emitted light.
The system evolved by Siemens Electric Lamps & Supplies Ltd is based on the two following fundamental facts: (1) If a lamp rated on a particular supply voltage is installed on a lower voltage, the light output, wattage consumption and operating temperature will be reduced (2) Lamps are manufactured to conform to the appropiate BSI specification in every respect, and if the bulbs of any number of lamps of equal ratings have exactly the same portions of their surfaces completely obscured, the untreated part or parts of each will radiate the same amount of light. A suitable black heat resisting pigment is used.
In order to obtain as even a flashing as possible of the lighting portion of internally illuminated signs or bollards, the portion of the bulbsurface lying directly between the filament and the surface to be illuminated should always be obscured. The best results would be obtained if all but reflected light were cut off. The lampholder would have to be moved as the relative positon of the lampholder slots with respect to the sign are not fixed.
The surface treatment will reduce heat dissipation and result in thermal increases in the lamps which will have an effect on life performance, but will be offset by the reduction of the operating temperature due to the electrical underrunning.
It should be understood that the absorption of glass panels, conditions of reflecting surfaces etc., will not be the same as those used in the experiments and it may be desirable or necessary to alter the amunt of lamp surface that is obscured in order to obtain similar results.
The necessity these days for the excercising of every economy coupled with reductions in staff due to war demands etc., may lead to less attention being paid to maintenance than would normally be the case, whereas existing conditions demand that greater care than usual be taken to enure these units be maintained.
Lighting: ARP, Lighting: Distribution, Lighting: Levels, Lighting: Maintenance, APLE: Lamps

Philplug Jointing Material p83
This has been produced to replace lead in ingot or fibrous forms in all classes of caulking and packing. It has already been accepted by the War Office and Air Ministry. Applications include joints between flanged pipes, making joints between electric light standards and cast iron bases etc., where lead is normally employed. Compared with lead a saving of about 45% can be effected. It does not require fire to make it ready for jointing.
Lighting: Personnel

Leeds Decides Upon ARP Lighting p83
Description of the new ARP Lighting to be installed in Leeds.
Lighting: ARP, Lighting: Installations

War-Time Street Lighting by Gas p84
The Ministry of Home Security is encouraging lighting authorities to install ARP street lighting fittings. War-time "starlight" lighting has proved its value in towns where it was installed last winter. "Starlight" lightign allows motorists and pedestrians to pass through the streets in greater safety, while there is a definite pyschological effect on public morale.
"When air raids disturb the public on a dark night, the light from the permitted street lamps may prove of incalculable value, as it is sufficient to facilitate movement and helps to diminish fear. Furthermore the ARP Services will greatly benefit by the assistance given by the lighting." wrote Mr. P. Good, Chairman of the Ministry of Home Security and Illuminating Engineering Joint Lighting Committee.
Among the many towns endorsing the benefits of war-time lighting are Sheffield, Bristol and Belfast. Sheffield's Lighting Engineer has expressed the view that limited tests may give the idea that the lighting is of little practical use; when, however, the lighting is installed on a large scale, the appreciation of the public is very real. This winter Sheffield will have 24,000 gas and electric lamps fitted for "starlight" lighting. Bristol, after early doubts on the subject, has converted the whole of its street lighting (there are over 6,000 gas lamps). Residents and police have both expressed their appreciation of the lighting. In Belfast, the new lighting has proved popular with the public.
With 800,000 gas lamps normally in commission, it's not surprising that large quantities of these untis have been ordered. Authorities who are still delaying are advised to make their wants known without delay. Manufacturers cannot risk the accumulation of large stocks and difficulties may be experienced in obtaining material. A sudden rush of orders may lead to delays in delivery, although the makers are in a position to satisfy orders at reasonably short notice.
Lighting: ARP, Lighting: Installations

To A Lamp Post by Kathleen Partridge p84
Short lament about the state of street lighting under war conditions. Repreoduced from The Daily Sketch
Lighting: ARP, Lighting: Social Comment

War-Time Damage To Public Lamps p85
Experience of bombing so far shows that damage to lamps and columns does occur, but it is not widespread and may be confined to one lamp in the immediate vicinity of the blast. It can be said that the effect of the blast is almost negligible as the column offers little resistence becuase the area per unit of length is small.
Even with the square type lantern, which has a relatively large superficial area with flat surfaces, the main damage by blast is broken glass, the interior fittings mostly remaining intact.
Where the bomb burst throws up a great amount of debris, damage may be considerable to adjacent lamps and columns. Masonry, bricks, etc., crash into and penetrate lamp casting and break cast-iron columns, while bomb splinters literally pepper columns and come out through the other side.
Where the bomb burst forms a crater in which a column is situated, then the column is completely uprooted, and possibly flung some distance away. Lamps in this case, can me completely destroyed.
Some people have advocated that all glass from street lamps should be removed. Experience has shown that often not even a pane of glass or a lamp globe is broken or cracked after a bomb blast.
"The explosion has brought down a large building but the column and lamp outside still stand as stolid as England herself, unflinching from the effect of Nazi barbarism."
It will be seen that damage to public lamps is not necessarily so great as had been expected.
Lighting: ARP

Crompton Parkinson A.R.P. Geared Ventilating Units p87
Details of ventilating units made by Crompton Parkinson. Home Office regulations allow approximately three to five times more people in a ventilated shelter than in an unventilated shelter of the same size.

Street Lighting Notes p88
Brief description of the installations at: Cheltenham, Chester, Colne, Edinburgh, Huddersfield, Kettering, Leamington, Lincoln, Lisburn, Northallerton, Paisley, Stretford, Tyneside and Wandsworth.
Lighting: Installations

APLE Annual Report p88
This has now been published and contains lots of useful statistics. "Miles Lighted - BS/ARP 37" notes that apart from London, Sheffield leads with a mileage of 600, representing 24,317 lamps. Leceister is another city that has shown enterprise with its war-time "Comfort" lighting: 241 miles have been installed, numbering 8750.
Lighting: Statistics

The Late Mr. James Lappin p88
Short obituary for Mr. James Lappin, for over 40 years a member of the staff of Glagow Lighting Deparment.
Lighting: Personnel

B.S.I. Specification 161 p88
The revised issue of the British Standard Specifications No. 161 relating to Tungsten Filament General Service Electric Lamps has now been issued. There are very few minor alterations.
Lighting: Specifications

Adverts: The General Electric Co., Ltd, APLE, Public Lighting, William Sugg And Co., Ltd., Siemens Electric Lamps And Supplies Ltd., Metropolitan Vickers Electrical Co. Ltd, Standard Telephones And Cables Ltd., The British Thomson-Houston Co. Ltd., Crompton Parkinson Ltd., Holophane Ltd., Ferranti Ltd. and The General Electric Co., Ltd.