MCCB for high-fault panels — what the ratings mean
The Siemens 3VA1120-5EF36-0BH0 is a SENTRON molded case circuit breaker (MCCB) with three poles, rated 20 A continuous at 40 °C and carrying a 187 kA interrupting capacity at 240 V — that is the short-circuit current it can safely clear without welding contacts or venting arc gas into the enclosure. At 415 V the breaking capacity is 121 kA; at 440 V it is 75.6 kA; at 500 V and 690 V it holds at 17 kA. The 800 V rated insulation voltage means the internal creepage and clearance are designed for 800 V systems, so the breaker can be applied in 480/277 V or 600 V panels with margin.
The breaker holds its full 20 A rating from 40 °C up to 55 °C; at 60 °C it derates to 19 A, and at 70 °C it stays at 19 A. That is a shallow derating curve, so in a warm panel the part still delivers close to nameplate. Maximum power loss is 14.5 W — useful to know when calculating enclosure heat rise.
Mechanical fit and panel integration
Dimensions are 76.2 mm wide (3 in), 130 mm tall (5.12 in), and 70 mm deep (2.76 in). The 3-pole footprint matches standard SENTRON 3VA panel cutouts and bus-bar centers.