320 A MCCB for line protection — TM240 release, 4-pole
The Siemens SENTRON 3VA1332-5EF42-0AA0 is a molded case circuit breaker (MCCB) designed for line protection in distribution panels. It carries a 320 A rating at 40 °C ambient, sustained across 45 °C and 50 °C without derating — at 55 °C it still holds 313 A, dropping to 292 A at 70 °C. That thermal curve matters when the breaker sits in a crowded enclosure with other heat sources. The TM240 overcurrent release combines a thermal-magnetic trip for overload and short-circuit protection. Four poles handle three-phase plus neutral switching, common in North American and IEC distribution schemes where a switched neutral is required downstream of the main disconnect. Breaking capacity is 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 11.9 kA at 690 V. At 240 V that is high enough for most secondary-side fault scenarios without cascading upstream. Rated insulation voltage is 800 V.
Panel fit and integration
Dimensions are 184 mm wide, 248 mm high, 110 mm deep. The width is the critical number for multi-breaker lineup spacing — 184 mm is a standard 4-pole MCCB footprint in the SENTRON 3VA platform. Front IP40 protection covers the operator interface; no IP rating on the sides or rear, so clearance to live parts inside the enclosure is assumed. Maximum power loss is 80.1 W. That is the heat the breaker dissipates at full rated current — factor it into enclosure thermal calculations, especially when mounting multiple breakers in a row. Operating temperature range is -25 °C to 70 °C; storage range is -40 °C to 80 °C. No undervoltage release, no shunt trip, no communication module on this variant — it is a straight thermal-magnetic line-protection breaker with no auxiliary electronics.