Facility/Home Exposure (TVSS / SPD Application Level) Surge Capacity/phase IEEE C62.41 Low Exposure Index <35 Medium Exposure Index 35 to 65 High Exposure Index >65 Category C (Service Entrance) 120kA to 160kA 160kA to 240kA 240kA to 400kA Category B (Distribution Panel) 50kA to 80 kA 80kA to 160kA 120kA to 240kA Category A (Individual Circuits) 50kA to 80 kA 50kA to 80 kA 50kA to 80 kA Unless otherwise indicated, all content, photos and art work published on this website are copyright property ©2005-2010 of PhaseFree.com and may not be republished without verifiable authorization from PhaseFree.com.  Click for our: Terms and Conditions