IEEE C37.81-1989 (R2005) pdf free.IEEE Guide for Seismic Qualification of Class 1E Metal-Enclosed Power Switchgear Assemblies. Abstract: IEEE C37.81 -1989, IEEE Guide for Seismic Qualification of Class 1E Metal-Enclosed Power Switchgear Assemblies, provides specific requirements and guidance for seismic qualification of metal enclosed power switchgear assemblies. This guide may also be used in other applications in which seismic response of...