What the 70 kA breaking capacity means for your panel
The Siemens 3VA1225-6EE42-0AA0-ZD00 is a 4-pole IEC frame 250 circuit breaker rated for 250 A continuous current. Its headline figure — 70 kA Icu at 415 V — places it in breaking capacity class H, meaning it can safely interrupt a fault current up to 70,000 A without welding its contacts or rupturing the arc chamber. That figure governs the SCCR (short-circuit current rating) of the panel it lives in: if your upstream transformer or utility feed can deliver 65 kA at the panelboard, this breaker clears it; if the available fault current exceeds 70 kA, you need a current-limiting upstream device or a higher-rated frame.
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.