The stability of metrological characteristics is one important aspect of durability. This part of IEC 62059 specifies a method for testing the stability of metrological characteristics of electricity meters, by operating a test specimen at the upper limit of the specified operating range of temperature, voltage and current for an extended period. Functional performance other than the accuracy of energy measurement is out of the scope of this standard. Note, that from the results of this test, no conclusion can be drawn for the length of period during which the stability of the metrological characteristics will be maintained when the meter is operated under usual conditions. This International Standard is applicable to all types of electricity meters in the scope of IEC TC 13.