This technical report applies only to circuit-breakers with their supporting structures which are rigidly connected with the ground, and does not cover the seismic qualification of circuit-breakers in metal enclosed switchgear. Where circuit-breakers are not ground mounted, for example in a building, conditions for application are subject to agreement between users and manufacturers. The seismic qualification of the circuit-breakers should take into account any auxiliary and control equipment which is mounted on the circuit-breaker structure. If the auxiliary and control equipment is mounted on a separate structure, it may be qualified independently. This technical report is a guide providing procedures to seismically qualify ground mounted circuitbreakers. The seismic qualification of a circuit-breaker is only performed upon request. This technical report specifies seismic severity levels and gives a choice of methods that can be applied to demonstrate the performance of circuit-breakers for which seismic qualification is required. NOTE In the USA, the evaluation of the seismic qualifications for circuit breakers is conducted in accordance with IEEE 693: IEEE Recommended Practice for Seismic Design of Substations.