IEC 62271-100:2008 is applicable to a.c. circuit-breakers designed for indoor or outdoor installation and for operation at frequencies of 50 Hz and 60 Hz on systems having voltages above 1 000 V. It is only applicable to three-pole circuit-breakers for use in three-phase systems and single-pole circuit-breakers for use in single-phase systems. This second edition cancels and replaces the first edition published in 2001 and its amendments 1 (2002) and 2 (2006). It also cancels and replaces IEC 61633 and IEC 62271-308. The main changes with respect to the previous edition are listed below: - the introduction of harmonised (IEC and IEEE) TRV waveshapes for rated voltages of 100 kV and above (amendment 1 to the first edition); - the introduction of cable and line systems with their associated TRVs for rated voltages below 100 kV (amendment 2 to the first edition); - the inclusion of IEC 61633 and IEC 62271-308. This standard shall be read in conjunction with IEC 62271-1, first edition, published in 2007.