Seismic Qualification of Electrical Equipment in Critical Facilities

Electrical equipment, particularly in critical facilities, should be subjected to seismic qualification. With this aim, seismic standards and codes should define essential requirements and harmonized prescriptive protocols. The main objectives of the present paper are to define the steering criteria for the seismic qualification of electrical equipment and to illustrate how to implement qualified equipment items in civil and industrial facilities. Special attention is given to critical facilities, whose operational continuity primarily depends on the integrity and functionality of the engineering systems and their equipment. A new approach to the seismic qualification is introduced, which highlights the need for different degrees of safety of the electrical equipment depending on the intensity of the expected ground motion, on the characteristics of the equipment item, on its location within the supporting structure and on life-safety considerations. The seismic demand to the equipment is defined in terms of Equipment Seismic Levels (ESL), while its inherent seismic capacity is classified in terms of Equipment Qualification Categories (EQC) and equipment weight. It is eventually recognized that certify and mark all the produced equipment items according to their qualified seismic capacity would allow a straightforward and reliable way to implement them in civil and industrial facilities.