40 A MCCB with 187 kA interrupting capacity — what the ratings mean for fit
The Siemens 3VA1140-5ED26-0AA0 is a 2-pole SENTRON molded case circuit breaker rated for 40 A continuous at 40 °C, with a TM210 thermal-magnetic release providing LI protection (long-time and instantaneous). The interrupting capacity is 187 kA at 240 VAC and 121 kA at 415 VAC — these are the maximum fault currents the breaker can safely clear at those voltages without welding or rupturing. The 187 kA figure at 240 V means this breaker is sized for high-fault-capacity service entrance or distribution panels where available fault current exceeds typical 25 kA or 65 kA MCCB ratings. The short-circuit release (Ii) is fixed at 400 A, which is 10× the continuous rating — a standard instantaneous pickup for motor or feeder protection where nuisance tripping on inrush must be avoided.
Mounting dimensions and panel integration
The breaker measures 130 mm high, 50.8 mm wide (2 inches — standard 2-pole MCCB footprint), and 70 mm deep. The 50.8 mm width means it occupies two 25.4 mm pole spaces in a panelboard or switchboard. The IP40 rating on the front face indicates protection against tools and wires greater than 1 mm, but not against water ingress — suitable for indoor panel mounting where the enclosure provides the environmental seal. The 70 mm depth is the body depth; account for handle throw and rear terminal clearance when laying out the gland plate or back panel.
Thermal derating and operating limits
The breaker holds its full 40 A rating from 40 °C through 50 °C. At 55 °C it derates to 39 A, at 65 °C to 38 A, and at 70 °C to 37 A. The maximum operating ambient is 70 °C; storage range is -40 °C to 80 °C. For a panel running warm — say 55 °C inside the enclosure — the continuous load should not exceed 39 A per pole. The power loss at rated current is 7.2 W maximum, which is low enough that forced ventilation is not required in a typical panel, but worth summing across multiple breakers in a sealed enclosure.
DC rating and application notes
The maximum rated operational voltage for DC applications is 250 V. The overcurrent release is the TM210 thermal-magnetic type with LI protection — thermal for overload, magnetic for short circuit. The breaker does not include ground-fault monitoring, communication functions, or a motor drive option. For DC switching power values, Siemens directs to the 3VA molded case circuit breaker device manual for specific derating curves.