Electrical power systems availability in buildings exposed to seismic hazard

The earthquake causes serious problems to the functional reliability and continuity of supply of electrical power systems particularly in exposed and sensitive structures as hospitals and strategic buildings. The paper discusses the need to study the requirements for the design and installation of electrical power systems in buildings subject to seismic hazard. Mechanical and electrical criteria for the design and the installation are recommended to be graduated according to building occupancy categories (as hospitals, strategic buildings). At least three levels of performance are identified for equipment. An important goal is to coordinate the non structural designing criteria with a layout of the system architecture that avoids or confines as possible intrinsically in a “duty-free” zone the seismic exposition and limits the same installation problems. A special power distribution, “brush-distribution”, has a laid structure suitably for the strategic buildings that are at risk for seismic event. Other general design criteria, such as a guarantee for the supply continuity, the system reliability and the system protection, have a special use in these appliances. The paper compares the brush distribution against the recommendations for the non structural components issued by the National Earthquake Hazard Reduction Program (NEHRP) (edition 2009).