Siemens SENTRON 3VA1120-5EF32-0BC0 — 20 A MCCB, 187 kA IC at 240 V
The Siemens SENTRON 3VA1120-5EF32-0BC0 is a 3-pole molded case circuit breaker (MCCB) rated for line-protection duty. It carries a continuous current of 20 A at 40 °C, with no derating needed up to 55 °C — at 60 °C it still holds 19 A, so it stays useful in warm panels without stepping up a frame size. Breaking capacity is the headline: 187 kA at 240 VAC, 121 kA at 415 V, 75.6 kA at 440 V, and 17 kA at 500 V and 690 V. That 187 kA at 240 V means it handles the full available fault current at a typical US secondary distribution voltage without needing a current-limiting upstream device — it clears the fault itself. The breaker ships with an undervoltage release (UVR) and two HQ auxiliary switches integrated. The UVR trips the breaker when control voltage drops below a set threshold — used in safety circuits or to coordinate with upstream contactors. The auxiliary switches provide status feedback to a PLC or panel lamp. Rated insulation voltage is 800 V, so it's suitable for 480/277 V and 600 V systems with margin. Power dissipation at rated load is 14.5 W — factor that into enclosure thermal calculations if the panel is densely packed.
Mounting and integration
Footprint: 76.2 mm wide (3 in), 130 mm tall (5.12 in), 70 mm deep (2.76 in). It mounts on a DIN rail or directly to a backplate via screw terminals. The 3-pole width is standard for a 20 A MCCB — plan for 3 module spaces on a DIN rail if using a terminal-block adapter.