What this MCCB carries — and what it doesn't
The Siemens 3VA1120-5EF36-0CC0 is a SENTRON molded case circuit breaker (MCCB) rated for 20 A continuous current (Iu) with a TM240 thermal-magnetic overcurrent release. That TM designation means fixed thermal and magnetic trip elements — no interchangeable trip unit, so the 20 A rating is locked at order. The breaker holds its full 20 A rating from 40 °C up through 50 °C ambient; it derates to 19.2 A at 55 °C, 18.8 A at 60 °C, 18.4 A at 65 °C, and 18 A at 70 °C. If your panel ambient runs above 50 °C, the effective ampacity drops — factor that into your load calcs. Breaking capacity is the headline here: 187 kA at 240 VAC, 121 kA at 415 VAC, 75.6 kA at 440 VAC, and 17 kA at 690 VAC. That 187 kA figure at 240 V is well above typical utility fault levels in North American 120/240 V split-phase panels — it covers high-fault scenarios like transformer-secondaries or large motor banks. At 415 V (common IEC industrial voltage), 121 kA still gives headroom for most distribution boards. The 690 V rating at 17 kA is lower but still adequate for many 690 V motor control centers. This is a 3-pole breaker with an undervoltage release (UVR) built in — the release design is listed as 3VA9608-0BB24. It also ships with 2 auxiliary switches HQ. That UVR means the breaker trips if control voltage drops below a threshold, which is common in safety circuits or emergency-stop chains. No communication function, no phase-failure detection, no ground-fault monitoring — this is a straightforward line-protection MCCB, not a smart breaker.
Panel fit and mounting
Dimensions: 130 mm height, 76.2 mm width, 70 mm depth. That 76.2 mm width is a 3-pole MCCB footprint — standard for Siemens 3VA frame sizes in this rating class. Front IP40 protection means it's splash-proof from the front but not sealed for washdown environments; mount it inside a cabinet, not exposed. The depth of 70 mm is shallow enough for most 200 mm deep enclosures with room for wiring gutters.