Annex A to joint CELMA / ELC Guide on LED related standards: Photobiological safety of LED lamps and lamp systems

Transcription

1 Annex A to joint CELMA / ELC Guide on LED related standards: Photobiological safety of LED lamps and lamp systems 1 st Edition, November Document CELMA LED(FR)003A

2 TABLE OF CONTENT 1. Introduction Legal bases CE marking of luminaires Assessment of the photobiological safety of luminaires by method 3a).. 3 Compliance with harmonised standards Assessment of the photobiological safety of luminaires by method 3b)... 5 Compliance by application of risk analysis results Conclusion

3 1. Introduction Higher luminous flux and improved efficiency mean that LEDs are being increasingly used as light sources in luminaires. To ensure that they are used safely, safety standards have been developed, as for conventional light sources. One aspect of light source safety is photobiological safety. This is concerned, for example, with the impact that radiation emitted by a light source has on the human eye. LED light sources are no different from other light sources in this respect but were covered in the past by standards developed for lasers. That situation has now been rectified in the case of LED light sources for general lighting service, i.e. it has been technically and normatively acknowledged that LED light sources of this kind have no relationship with lasers. Remark This paper looks at the legal basis and conformity assessment for line-voltage operated luminaires for general lighting service. Comparable safety requirements exist for luminaires for special purposes or with operating voltages outside the scope of the Low Voltage Directive but the special at times differing regulations and conformity assessment procedures relating to them are not examined here. 2. Legal bases The European Directive on General Product Safety 2001/95/EC and the European Low Voltage Directive 2006/95/EC require that no hazards should be presented by radiation and of course the same is applicable to the radiation emitted from LED light sources and LED luminaires. The requirement applies as a matter of principle to all electrical equipment that falls within the scope of the EC Low Voltage Directive (exceptions include equipment for use in explosive atmospheres, in medical engineering, on ships, in aircraft or in trains) and thus forms the basis for European safety considerations. In addition, the European Union created another legal basis in adopting the Directive 2006/25/EC (Optical Radiations) laying down "minimum health and safety requirements for protection of workers from risks arising from exposure to artificial optical radiation". Member states are required to implement this directive by 27 April CE marking of luminaires Electrical equipment may be placed on the market in the EU only if the basic requirements of the relevant European directives (transposed into national law) are observed. Photobiological safety is one such product requirement. The CE marking indicates to government agencies that a product conforms to all the relevant directives, provided they require CE marking. CE marking under the EC Low Voltage Directive is done on a manufacturer's own responsibility. Before doing so, however, the manufacturer needs to make sure that the requirements of all the European directives applicable to the product in question are met, i.e. each requirement needs to be verified and its fulfilment documented in the EC conformity declaration and technical test reports. Luminaires are normally subject to the EC Low Voltage Directive (LVD) and the EMC Directive. Both directives permit the use of conformity assessment procedure Module A. Module A involves monitoring and inspection of design and production on the sole responsibility of the manufacturer without the participation of a designated agency. Implementing measures for the "Energy Using Products" framework directive, are not examined here

4 Compliance with the fundamental requirements of EU directives can basically be demonstrated in two ways: 3a) Compliance with harmonised standards Harmonised standards in support of the relevant European directives (LVD, EMC etc.) are periodically published in the Official Journal (OJ) of the European Union. Compliance with the requirements set out in these standards is accepted as conformity to the statutory requirements (the principle is known as "presumption of conformity of harmonised standards"). Where a manufacturer applies the harmonised standards relevant for a particular product and documents the fact clearly, the CE mark may be applied and the product marketed. In certain exceptional cases, however, the fact that a product conforms to standards is not sufficient evidence of the safety required by directives. One such instance, for example, is where the state of the art has changed, which is what actually happened in the case of IEC :1993 (EN :1994). IEC :2007 was the state of the art but LED light sources for general lighting service were excluded from it. If IEC :1993 had been taken as the basis for conformity assessment, wrong results could have been produced because classification was based on a maximum exposure time of 100 seconds. That is possibly too short for dominating photochemical (i.e. dosedependent) damage where exposure is chronic. Exposure times to laser are not normally long but they certainly are in the case of lighting. Hence the fact that Risk Group 0 (retinal blue) in IEC has a limit of 10,000 seconds. Moreover, laser's monochromatic characteristics cannot simply be applied to polychromatic "white" LED light sources. This is why it was recommended that IEC :1993 should not be applied. EN 62471:2008 on the photobiological safety of LED light sources was ratified by CENELEC BT (Technical Office) on 1 September This enshrined a judgment that takes account of lighting requirements and should be adopted by all market players as swiftly as possible. 3b) Compliance by application of risk analysis results As an alternative to applying harmonised standards, manufacturers have the option of using measures of their own that can be shown to result in the fulfilment of statutory requirements. An important basis for such measures is risk analysis. The risk analysis performed needs to be detailed and is normally difficult because the basic requirements are formulated in very general terms. In certain cases, risk analysis may result in assessment based on standards or other technical/physical specifications that are not published in the Official Journal of the European Communities and thus do not enjoy presumption of conformity. The conformity declaration then needs to be made on the basis of the risk analysis and compliance with the standards or technical/physical specifications used. Since the ratification of EN 62471:2008 for LED lighting, this option is no longer recommended. 4. Assessment of the photobiological safety of luminaires by method 3a) Compliance with harmonised standards The list of references for the Low Voltage Directive currently contains only EN : A1: A2:2001 "Safety of laser products, Part 1: Classification of equipment, requirements and user guide". It is assumed that the new EN 62471:2008 will also be listed soon

5 EN 62471:2008 (CIE S009) "Photobiological safety of lamps and lamp systems" reflects the state of the art today and is recommended for immediate use. The standard sets out requirements in terms of limiting values, methods of measurement and classification criteria; it does not lay down a requirement for conformity marking. The classification of lamps/luminaires is based on hazard values reported at a distance which produces 500 lux illuminance, but not at a distance less than 200 mm. LED light sources for general lighting are not normally IR or UV radiators, so Table 2 confined to hazards that may actually be presented does not include infrared and ultraviolet hazards. LED light sources do not reach Risk Group 3, which is for special light sources in extreme circumstances. Measurements have shown that state-of-the-art high-performance LEDs reach no higher than Risk Group 2: safety (as in Laser Class 2) due to aversion response to very bright light. Table 2 Risk Groups according to EN 62471:2008 Risk of photobiological damage Risk of photochemical retinal damage LB Risk of thermal retinal damage LR Exempt Group Risk Group 1 Risk Group 2 Risk Group 3 none low moderate high 2.8 h 100 s 0.25 s < 0.25s 10 s 10 s 0.25 s < 0.25s For the photobiological parameters (e.g. risk of photochemical retinal damage) of each risk group, wavelength-weighted emission limits have been defined as a basis for classification. The individual risk groups are defined as follows: Exempt Group: Luminaires present no photobiological hazard. Risk Group 1: Luminaires present no hazard due to normal behavioural limitations on exposure. Risk Group 2: Luminaires present no hazard due to the aversion response to very bright light sources or due to thermal discomfort. Risk Group 3: Luminaires present a hazard even for momentary or brief exposure. Use in general lighting service is not allowed. IEC gives all information about the test method and classification of the light source, but does not give any requirement about limitation of use and marking requirements in case of risk group other than Exempt group. IEC/TR has been published for this scope. This technical report has been issued to be a reference document for Technical Committee to improve the product standards, but it may be used as guide for luminaire and light source marking. 5. Assessment of the photobiological safety of luminaires by method 3b) Compliance by application of risk analysis results As described in section 3b), a manufacturer can conduct a risk analysis, although experts have for some time recommended the application of IEC 62471:2006 (CIE S009). Now that this dedicated lighting standard has been ratified as an EN, however, it is advisable to use EN 62471:2008 for assessing the photobiological safety of lamps and lamp systems

6 6. Conclusion As a matter of principle, the classification of luminaires needs to be performed on the basis of predictable non-conformity. Exemptions are luminaires with surface-emitting LEDs such as those used at present for lighting and indicating purposes. These components are only capable of briefly exceeding radiation safety limits. e.g. in the event of control circuit failure. Classification of individual components (e.g. individual LED modules) makes sense because it provides valuable information for the luminaire manufacturer. Not every luminaire will change risk group as a result of the use of extra optics and classifying LED modules saves the need for repeat luminaire measurements by the luminaire manufacturer. However, if lenses or other optical systems alter the intensity of radiation, a photobiological assessment of the luminaire needs to be performed regardless of the LED radiation data. In this case, the LED data represent an important "raw data" variable. Control gear also plays a key role here because the operating points and mode of operation of LED modules (e.g. pulsed operation or operation outside normal operating point data) are determined by the control gear. Which option a luminaire manufacturer selects as the basis for the EC conformity declaration (3a or 3b) is a matter for the manufacturer's judgment and discretion. However, luminaire manufacturers are under an obligation to apply the current state of the art (e.g. EN 62471:2008). As a general rule, LED/LED module manufacturers' information (specification sheets) should be studied. If the LED modules described have been classified, their classification should be taken as the basis for conformity assessment by the luminaire manufacturer. LED/LED module manufacturers are advised to furnish product data in line with EN 62471:2008 requirements. (IEC product data stipulations are not applicable to general lighting because of extreme conformity marking requirements) Finally, it needs to be stressed that, in terms of photobiological safety, LED light sources are no exception against other, conventional light sources (e.g. the high-pressure discharge lamps or high-performance fluorescent lamps used in many luminaire applications)