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 2005-2018 of PhaseFree.com and may not be republished without verifiable authorization fromPhaseFree.com.  Click for our: Terms and Conditions