Light & Engineering Vol. 23, No. 4, pp. 69-74, 2015 Svetotekhnika No. 4, 2015, pp. 18-22 DEGRADATION OF LIGHT EMITTING DIODES: THE CONNECTION BETWEEN OPERATING CONDITIONS, AND ACTUAL AND DECLARED SERVICE LIFE Dmitry Yu. <...> Yurovskikh The Representative offi ce of Cree Hong Kong Limited, Moscow E-mail: Dmitry_Yurovskikh@cree.com ABSTRACT The article explores the service life of light emitting diodes and their luminaires. <...> Approaches to the evaluation of service life are proposed, and some principal causes of product failures dependent on specifi c operating conditions are considered. <...> Recommendations are given regarding what is important when evaluating the durability of light-emitting diode luminaires. <...> Keywords: light emitting diodes, service life, luminaires with light emitting diodes, failure criteria, Electrical Overstress Today it can be stated confidently that the light-emitting diode illumination revolution has occurred. <...> Light emitting diodes (LED) have found their way into street, offi ce, trade, household and industrial illumination, as well as into households and the communal services sphere. <...> However, consumers take the declared levels of reliability and durability of luminaires with LEDs (LEDL) incredulously. <...> This is natural, because in such spheres as street, industrial and trading illumination, LEDL introduction is a signifi cant investment as their payoff period is quite slow: as a rule, no less than a year. <...> LEDL failure is much more unpleasant, than the failure of a simple lamp, at least because lamp replacement is a simple process, which the consumer can manage single-handed. <...> On the other hand, LEDL replacement or repair demands involvement of a service company or of the LEDL 69 manufacturer. <...> This is due to the fact that the lamp concept in itself cannot be used with LEDLs. <...> Consumers frequently have a limited understanding of the difference between the LED and LEDL concepts. <...> The service life of a luminaire with a traditional light source is the time of its operation to the moment of catastrophic failure, i.e. a full termination of the operation, for example, because of burnout of the light source or ballast malfunction. <...> Relative to LEDLs, we apply the concept of parametric failure because burnout of the light source in a LEDL is rarely <...>