What this MCCB is and what the ratings mean for fit
The Siemens SENTRON 3VA2140-5JQ46-0AA0 is a 4-pole molded case circuit breaker (MCCB) rated for 40 A continuous current, designed for line protection in distribution panels. Its 40 A rating holds flat across the full ambient range from 40 °C to 70 °C — no derating needed as the panel warms up, which simplifies sizing in a crowded enclosure. Breaking capacity is the headline number: 187 kA at 240 V, 121 kA at 415 V and 440 V, 75.6 kA at 500 V, and 3.7 kA at 690 V. That 187 kA at 240 V means it handles high-fault scenarios on the low-voltage side of a step-down transformer without needing a current-limiting fuse upstream — a real space saver in a panel. It includes ground-fault monitoring via summation current formation on the L + N conductor, so it catches leakage on the load side without a separate GFCI module. That's one less device to wire and one less DIN rail slot consumed.
Physical fit and panel integration
Dimensions: 181 mm height, 140 mm width, 86 mm depth. That 86 mm depth keeps it clear of most gland plates and back-panel wiring channels — no need to force a deeper enclosure just to clear the breaker body. The 140 mm width is a standard 4-pole MCCB footprint on the DIN rail; it drops into the same cutout as other SENTRON 3VA 4-pole units.