What the 70 kA breaking capacity means for your panel
Trip unit and adjustment range
The TM220 thermal-magnetic trip unit provides overload protection adjustable from 175 A to 250 A (Ir) and a fixed short-circuit pickup of 10 x In (Ii = 2,500 A). The thermal element follows an inverse-time curve — it responds to sustained overcurrents, not inrush — so it's sized for cable protection or as a main breaker in a distribution panel. The magnetic instantaneous element clears hard shorts without intentional delay. Note the N conductor is unprotected on this variant; the neutral pole passes through without a trip element, which is standard for line-side main breakers where the neutral is bonded to ground upstream.