Analysis of possible LED failure mode

New technologies are emerging in illumination field. In particular the LEDs are beginning to spread always more in the world of the lighting. It is very important to analyze and to know the possible failure modes of LED sources in order to design reliable and safe lighting fixtures, especially if we consider the use of LED lighting equipment in potential explosive atmospheres. Indeed they require a quite complex safety system in order not to trigger dangerous gases, vapors and dusts. Today, IECEx Standards do not adequately take into consideration the potential of the actual LED luminaires for Ex environmental, both with white light and with colored light. Nowadays, Standards only consider LEDs adequate for installing in Zone 1, if the luminary is realized by the same protection strategy designed for traditional light sources, for Ex-d mode, or if the luminary guarantees a big limitation in terms of voltage and installed power, for Ex-i mode. In particular, Ex-d LED luminaires are obtained by using the same protection strategy designed for traditional light sources (incandescent, discharge, induction), formed by heavy, thick and flameproof enclosures. Therefore, the safety of such equipment is entrusted exclusively to the mechanical strength of the case and not from the internal electrical equipment. While the flameproof enclosures ensure great heat dissipation to the LEDs, on the other hand greatly reduce luminous efficiency of the appliance itself, since the glass used are also very thick (10% reduction of approximately every 10mm of thickness of the glass). The paper shows a study about currently available LED's electrical and mechanical characteristics, which evaluates different possible causes of failure and their implication with explosive atmospheres.