From oil lamps to electric lighting
The need for drivers to see other vehicles – and to be seen by them – after dark emerged naturally as soon as cars first appeared on roads. Lighting had been present on horse-drawn vehicles for a long time because of the same requirement.
Initially, in the 1880s, cars were fitted with acetylene and oil lamps. Electric lamps were first introduced on a large scale in the 1920s. Early car electrical systems were rather unstable and the lamps were subjected to harsh conditions: shock and widely varying climatic conditions and temperatures. All of these contributed to the somewhat slow introduction of electric lamps.
Other lamps besides headlamps and tail lights have been introduced gradually to meet additional needs. They include fog lamps and various kinds of signalling lamps, such as indicators and brake, emergency, parking side marking and reversing lights. Other types of lamps may be required for other categories of road vehicles such as lorries or buses.
The need for International Standards
Road vehicles are produced and traded globally and are used regularly across national borders. The need for International Standards is obvious: road safety requires that lights are standard in terms of characteristics such as performance, colour durability and interchangeability.
The UNECE (UN Economic Commission for Europe) is the international body that sets many of the regulations that "facilitate the international movement of persons and goods by inland transport modes" through its World Forum for Harmonization of Vehicle Regulations (WP 29). Its Working Party on Lighting and Light-Signalling (GRE) is the subsidiary body that prepares regulatory proposals on active safety for vehicle lighting and light-signalling. This group of experts conducts research and analysis to develop lighting requirements for vehicles.
Much of the GRE's work depends on and references various IEC International Standards on lighting for road vehicles prepared by IEC SC (Subcommittee) 34A: Lamps, of IEC TC (Technical Committee) 34: Lamps and related equipment.
Evolving standards for road vehicle lamps
IEC 60809, Lamps for road vehicles – Dimensional, electrical and luminous requirements, sets out the requirements (marking, colour, dimensions, caps and bases, UV radiation, etc.) and test conditions for filament and discharge (xenon) lamps. IEC 60810 Ed3.2, Lamps for road vehicles – Performance requirements, details the basic function and interchangeability, mechanical strength, some life characteristics (measured on a test quantity of 20 lamps), lumen maintenance, resistance to vibration and shock, and glass-bulb strength published for the same types of lamp (filament and discharge).
In addition, as lighting solutions based on LED (light emitting diode) technology have been phased in gradually – first to top of the range cars and then to a broader class of vehicles – this standard, published in February 2013, contains updates including the requirements and test conditions for LED light sources, as these may be significantly different from those that apply to other types of lamps.
They include basic function and interchangeability, UV radiation, lumen and colour maintenance, resistance to vibration and shock, electromagnetic compatibility and powered thermal cycling. This last characteristic determines the ability of the LED light source to withstand changes of ambient temperature. Tests and requirements for filament and discharge lamps are based on IEC 60809 data sheets for different types of lamps.
All lamps (including LED-based ones) must also comply with IEC 60061-1, Lamp caps and holders together with gauges for the control of interchangeability and safety.
Wide adoption of latest standard is expected
As LED-based lighting solutions are being introduced by all car manufacturers, IEC 60810 Ed3.2, which now includes requirements and test conditions for LED light sources, will be adopted widely by the automotive industry, contribute to the introduction of new safer lights and form part of the reference documentation used by the GRE in its work.