Standards emerge specifically for SSL test methods (MAGAZINE)
European standards, driven primarily by the IEC, increasingly address safety and performance issues that are specific to LED-based lighting, explains Pasi Orrevetelainen.
This article was published in the July/August 2013 issue of LEDs Magazine.
View the Table of Contents and download the PDF file of the complete July/August 2013 issue, or view the E-zine version in your browser.
In recent years, a large variety of LED-based solid-state lighting (SSL) products has emerged on the market. LEDs have now realized their full potential for everyday illumination, rather than being limited to specialty applications. The ever-increasing number of LED products particularly represents a challenge to test laboratories, whose task it is to check for product safety. Generally, safety testing is carried out by testing products against relevant product standards. However, when new technologies such as SSL emerge, no specific product standards exist and so only related standards can be applied. Fortunately, this situation has now markedly improved in the LED field around the globe; we will discuss the regulatory landscape in Europe.
The standards for LED lighting products can be roughly divided into two groups: safety and performance. As the terms imply, the first group is mainly concerned with the safety issues related to products, while the latter focuses on the performance of the products. Some overlaps occur in the standards, because some requirements may be safety oriented but are located in the performance standard and vice versa.
In Europe, the safety of the lighting product has to be ensured according to the Low Voltage Directive 2006/95/EC. In the Low Voltage Directive, the application of performance standards is not mandatory, because they do not affect the safety of the product. Performance standards specify requirements for how to test the performance characteristics of products. Most of the tests included in performance standards verify properties claimed by the manufacturer. Less frequently, performance standards specify absolute requirements the product should fulfill.
LED lamps regulation
Due to an increasing interest in energy savings, LED lamps have become more and more commonly used as the preferred alternative to incandescent lamps. Until October 2012, it had therefore been an awkward situation in Europe, since there were no specific EN standards for LED lamps.
EN 62560, which now becomes the standard for self-ballasted, single-capped LED lamps, was only ratified in October 2012. Previously, combinations of other EN standards were applied to check the safety of products. However, the corresponding IEC 62560 standard has been valid since February 2011.
EN 62560 covers LED lamps that replace familiar mains voltage household lamps. As it is only intended for self-ballasted lamps, lamps with external control gear, or drivers, are not within the scope of the standard. Standards for such lamps are under development. The primary purpose of the standard is to ensure that the product is not and will not become unsafe during its lifetime in normal use. This goal also applies to cases where the lamp is damaged. The lamp must not impair safety even when the electronics inside the lamp fail. The standard also concentrates on the fact that the LED lamps will replace ordinary incandescent and compact fluorescent lamps and therefore should not have properties that impair the safety of the luminaires in which the lamps are installed.
The safety standard for double-capped LED lamps, which are intended to replace double-capped linear fluorescent lamps, is currently being developed. The primary concern for these lamps is their metallic surface. As metal conducts electricity, the safety distance from live parts, termed the creepage distance and clearances, is relatively large in order to ensure that any accessible metal parts do not become live with mains voltage under any circumstances.
Safety of luminaires
The EN 60598 standard series relates to the safety of luminaires. This series does not have special requirements for LEDs; instead the common requirements of luminaires have to be fulfilled by SSL luminaires. In addition, LED modules and control gear must comply with their own standards. Although this is not currently mentioned in the EN 60598 standard series, the safety of photo-biological radiation has to be assessed according to standard EN 62471. (For more information on photo-biological safety, see "LED-based products must meet photobiological safety standards: part 3".)
EN 62471 deals with safety aspects of radiation between 180 and 3000 nm, which includes ultraviolet (UV), visible, and infrared (IR) radiation. Ordinary LEDs intended for illumination do not radiate harmful UV or IR, so only visible radiation is considered for LED luminaires and more specifically for the Blue Light Hazard (BLH). With its high energy content, blue light detrimentally affects the eyes. Therefore, luminaires have to be properly marked if the limits of safe radiation are exceeded.
The components related to the safety of the luminaire, either internal or external, have to further comply with their own safety standards.
LED modules and control gear
Usually, several LEDs are combined in SSL fixtures. The printed circuit board on which the LEDs are placed is often called an LED module or light engine. The safety standard for LED modules is EN 62031. LED modules can be self-ballasted, which means they have a driver or control gear integrated on the module. However, it is more common for the control gear, which supplies the LED module with its correct voltage and current, to be a separate unit. For a separate control gear, the standard EN 61347-2-13 applies. The EN 61347 series is intended for control gears and ballasts of various types of lamps. Parts 2-13 are intended specifically for the control gears of LED modules.
As LEDs do not need very high voltages to operate, it has become popular to provide an extra-low voltage (ELV), less than 25V RMS, to LED modules. Relying on ELV levels to the modules simplifies module safety assurance. If the voltage of the LED module is low enough, it is safe to touch the LED module with bare hands. However, this requires that the LED control gear is classified as safety extra-low voltage (SELV) or an SELV equivalent. The requirement for SELV is not only a low voltage, but the SELV circuit also must be separated from the mains supply by double or reinforced insulation. Thus, if an LED module claims to be SELV, it requires that the control gear is very safe as well.
LED products already have their own performance standards. Most of these standards are IEC/PAS, which indicates that they are Publicly Available Standards or pre-standards.
EN 62384 is the standard for LED control gear performance. As mentioned earlier, most of these requirements relate to the properties claimed by the manufacturer. However, besides an endurance test, there are requirements for abnormal conditions that the control gear has to withstand. During and after these tests, the control gear should function normally.
The IEC 62707 series is a family of performance standards intended for individual LEDs. The series is under development and the IEC has currently published one standard — IEC/PAS 62707-1 — concerning the color binning of white LEDs. Two additional parts of this standard will cover LED binning according to luminous flux and forward voltage.
The performance standards for self-ballasted LED lamps (IEC/PAS 62612), LED modules (IEC/PAS 62717), and LED luminaires (IEC/PAS 62722-2-1) will present a broad range of requirements from electrical properties to lumen maintenance and include colorimetric properties and their maintenance during the product's life. These standards include tests lasting up to 6,000 hours.
The European SSL regulatory landscape is summarized in the table nearby (click the table to enlarge). Companies that intend to sell their LED-based products in Europe should engage with a testing lab to have the products tested to the relevant harmonized safety and performance standards. Moreover, competent test labs will be able to counsel product manufacturers on the ever-shifting landscape of LED-centric regulatory issues.