This technical report IEC/TR 62271-310:2008 is applicable to class E2 circuit-breakers above a rated voltage of 52 kV and above intended for use on overhead lines. The test programmes are based on accumulated electrical stresses due to current interruption during a period of 25 years, which was chosen as representative for a maintenance-free interval. This second edition of IEC/TR 62271-310 cancels and replaces the first edition published in 2004. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - reduction of number tests in the wear stage; - new definition of acceptance test for demonstration of end-of-life thermal interruption capability.