The EZS400N3400 is a 3-pole molded case circuit breaker from Schneider Electric's EasyPact EZS range, rated 400 A at 40 °C with a TM-D thermal-magnetic trip unit. The 70 kA Icu at 240 V AC (50/60 Hz) breaking capacity means it can safely interrupt fault currents up to that level without failing — critical for high-fault panels where upstream coordination depends on the breaker clearing a short before the transformer or main switch trips. At 400 V AC the Icu is still 50 kA, which covers most industrial distribution boards fed from a 500 kVA or smaller transformer. The breaker is rated for isolation (suitability for isolation: yes), so it doubles as a visible-break disconnect when locked off.
Fixed backplate mount, 150 mm wide × 257 mm high × 108 mm deep. The 45 mm connection pitch and front-facing terminals (both line and load side) make it straightforward to bus-bar in a standard distribution panel. Neutral is on the left. IP40 enclosure protection keeps tools and fingers out; IK07 impact resistance handles incidental knocks during panel wiring.