Early examples included decorative spigot caps, finials and scrollwork. They were often fashioned into a curved shape known as a swan neck.

They are often revised and updated. The current standards (2003) are:

BS 5489 Part 1: Lighting of roads and public amenity areas.
BS 5489 Part 2: Tunnels.
BS EN 13201 Part 2: Performance requirements.
BS EN 13201 Part 3: Calculation of performance.
BS EN 13201 Part 4: Methods of measuring lighting performance

BS EN 13201 Part 1 will no longer appear as a standard, and will probably appear as a guideline document.


Previous standards were:

• BS 307/1931: Street Lighting. Published in 1927.

  It specified a test point and minimum illumination values (as foot candle classes):

  Class	Minium Illumination	Minimum Height Of Source	Spacing Recommended	Spacing Height Ratio
  A	2.0 foot candles	30 feet	90 feet	3
  B	1.0 foot candles	25 feet	100 feet	4
  C	0.5 foot candles	21 feet	105 feet	5
  D	0.2 foot candles	18 feet	108 feet	6
  E	0.1 foot candles	15 feet	105 feet	7
  F	0.05 foot candles	13 feet	104 feet	8
  G	0.02 foot candles	13 feet	130 feet	10
  H	0.01 foot candles	13 feet	130 feet	10

  It allowed a simple way to order and check the work of contractors and give general guidance in the planning of new work.
  
  
  

• BS 398/1930: ???. Publication date: 1927-1935

  This documented specified the symmetrical light distribution from light fittings. Street lighting was part of the "Direct" class, and not less than 90% of the flux was in the lower hemisphere. The polar curves were divided into five classes:-

  1. Extra Narrow

  2. Narrow

  3. Intermediate

  4. Wide

  5. Extra Wide

  By the 1930s it was realised that both these reports were unsuitable, and had lead to some very highly directional reflectors and refractors giving narrow beams of high intensity, leading to glare and streakiness on the road.

  They set a fashion for high peak intensity.

  They were quickly succeeded by the MOT report in 1937 and subsequently obsoleted.
  
  
  

• BS 1308: Reinforced Concrete Street Lighting Columns. Published in 1946.
  
  
  
• BS 1249: Cast Iron Street Lighting Columns. Published in 1951.
  
  
  
• BS 1788: Street Lighting Lanterns. Published in 1951.

  This document covered the mechanical and constructional features of lanterns, with regard to safety, durability and easy of maintainance.

  It did not cover photometric requirements.
  
  
  

• BS Code Of Practise (BSCP) 1004 Part One: Street Lighting - Traffic Routes. Published in 1952.

  This refined the MOT Report of 1937 on Group 'A' roads and was supplimented by BS 1788 which was published the previous year.

  The total downward light the now the most important.
  
  
  

• BS 1840: Tubular Steel Columns for Street Lighting. Published in 1952.
  
  
  
• BS Code Of Practise (BSCP) 1004 Part Two: Street Lighting - Roads other than Traffic Routes. Published in 1956.

  Light distribution in plan should be suited to environment.

Left: The BTH Urban Enclosed (SM278) - available as both side and top entry.

Left: The DAVIS GR100 - originally an ELECO design.

Left: The Eleco Lunar (PT 1006) - an example of a striking design.

The first incandescent bulbs used carbon filaments in a vacuum; these were then replaced by tungsten filaments in a vaccum; to be finally superceeded by gas filed tungsten filament bulbs. (An inert gas was pumped into the bulb to slow down the loss of tungsten atoms from the filament).

The original bulbs used a coiled filament, whilst coiled coil tungsten filament lamps started appearing in the 1930s: these became the standard. Old 1930s open GLS lanterns (such as ESLA Bi-Multis or BLEECO open dome refractor lanterns) should be fitted with clear single coil bulbs.

Typical wattages are: 40W, 60W, 75W, 100W and 150W (for Group B roads); 200, 300, 500 and 1000W (for Group A roads).

Variations of the GLS source are:

Clear Lamps: These are clear glass bulbs.

Pearl Lamps: Are the most common types of incandescent lamp. These are internally etched to produce a diffusing finish and usually have a grey unlit appearance.

Opal Lamps: Are less common, being sprayed inside with a diffusing coating. They have a white unlit appearance (similar to a coated elliptical MBF or SON).

1. The brightness of the lamps.
2. Position relative to the observer.
3. A factor which takes account of the relative movement of observer and lamp.

This became the standard.

1. Spinning
   1. Steel
   2. Copper
2. Fabricated Box
3. Casting
   1. Iron
   2. Silicon Aluminium
      1. Gravity Die
      2. Pressure Die
   3. Plastic Moulding

1. Reflector
   1. Vitreous Enamel
   2. Glass Or Plastics
      1. Silvered
      2. Aluminised
      3. Prismatic
   3. Anodised Aluminium
2. Reflector-Refractor
3. Refractor
   1. Single Piece
   2. Sealed Two Piece
   3. Glass
      1. Soda-Lime
      2. Heat Resisting
   4. Plastic
      1. Processed Sheets
      2. Injection Moulding
4. Diffuser

1. Incandescent Filament (GLS)
2. Discharage Lamp
   1. Low pressure sodium (SO/H)
   2. Mercury
      1. Discharge MA/V, MA/H, MB/U
      2. Blended MBT/V
      3. Bulb Fluorescent MBF/U
      4. Tubular Fluorescent MCF/U
3. Gas
   1. Low pressure
   2. High pressure
4. Arc Lamp

1. Prestige And Display
2. BS Code Of Practise
   1. Group A
      1. High Angle
      2. Medium Angle (including Aeroscreened)
      3. Cut-Off
      4. Uni-Directional
   2. Group B
      1. Narrow B1
      2. Wide B2
      3. Tree Lined

400W bulbs were first available, quickly followed by 250W units. A 150W version was launched in 1936, but, due to the medium pressure of the mercury vapour, suffered from efficacy problems. Therefore the race was on to develop a high pressure version of the bulb which could operate well at lower wattages.

The orientation of lamp burning was also important, and several designations were used:

/V Vertical cap up

/D Vertical cap down

/H Horizonal

/U Universal

Mazda (BTH) sold the lanterns under their Mercra name. The GEC could only use the Osram name for tungsten filament lamps, so sold their mercury lanterns as Osira up until the second world war. Philips used Philora, whilst Siemens used Sieray.

Siemens were advertising the Sieray-Dual Lamp in 1936 as a combination of mercury discharge lamp and tungsten filament. The light quality was considered better from this bulb, and it didn't require any gear (the tungsten filament acting as ballast with its fixed resistance). The designation for this bulb became MAT and was also known as Blended Mercury.

There were a couple of variants (which extended the lamp's code):

T With a tungsten filament. See above.

F Coated with a fluorescent power to improve the light quality.

1. Hand operated (both individual and group)
2. Time clock operated (both individual and group)
3. Centralised control using high frequency impulse or DC Bias.
4. Contactors in cascade.

They published their first report in 1937 (with an interim report in 1935 which covered main roads only) which superceeded and obsoleted the British Standards 307 report of 1927. The amount of light from a lantern was just one criterion (it was the principle subject of BS 307). Definite spacial arrangements of lanterns in terms of height and distance were standardized, and there were limits placed on the peak intensity of the beam, leading to improvements of glare. It was also the first document to divide roads into Group 'A' and Group 'B'.

1. Symmetrical
2. Axial Asymmetric
3. Non-Axial Asymmetric
4. Uni-Directional

1. Low labour costs for maintainance.
2. Lanterns more easily cleaned on the ground.
3. Maintenance can be effected without causing a traffic obstruction.
4. Elimination of risk of accidents with tower wagons.
5. However... installation costs more and additional equipment needs maintaining.
6. Jarring and shock can cause filament or bulb failure.

It appeared that this first installation (100W DC) was installed in bucket-type cut-off lanterns. It lasted four years before being replaced with a larger installation of Wardle Liverpools on a catenary system, which lasted until the 1970s.

The bulb was typified by a two piece construction - the inner arc tube was enclosed in an outer tube which comprised a Dewar flask. When the inner tube was spent, it was removed and replaced - the outer tube, which was expensive to construct, was retained.

The Dewar vacuum chamber provided thermal insulation, allowing the inner tube to reach its optimum temperature of 260^oC.

The original wattages and efficiencies were:

Philips sold the bulb under the Philora name - technical information can be found here.

On the 15th Novemebr, 1938, ELMA reclassified the wattage and efficiencies as follows:

By the early 1960s, the efficiencies of the lamps had improved:

The orientation of lamp burning was also important, and several designations were used:

/V Vertical cap up

/D Vertical cap down

/H Horizonal

/U Universal

Such a device would be used for SOX, SOX Plus and SOX-E.

DAVIS also sold this device as a converter unit from MBF to SON. Chokes can be connected in series, so the low loss choke decreased the wattage by a set amount (from 80W for MBF to 70W for SON for instance) and the thyristor acted as an ignitor.

A data sheet for these devices can be found here