The Siemens SENTRON 3VA4120-5ED54-0AA0 is a 1-pole molded-case circuit breaker (MCCB) in the system-protection version, rated 20 A continuous at 40 °C with a TM210 thermal-magnetic release (LI characteristic — long-time and instantaneous protection). Its interrupting capacity is 85 kA at 120 V AC, 35 kA at 277 V AC, and 18 kA at 347 V AC — numbers that govern where it can be placed in a distribution panel without cascading upstream. The 85 kA at 120 V is the headline figure; the 18 kA at 347 V is the one that matters for 347/600 V wye systems common in Canadian and some US commercial installations. The 75.1 mm depth and 50.8 mm width mean this breaker fits the standard 1-pole footprint in a SENTRON distribution panelboard — no extra gutter space needed for the line-side lugs.
Thermal derating — real-world current at panel ambient
At 50 °C it derates to 19 A, at 60 °C to 18 A, and at 70 °C to 17 A. Maximum power loss is 2.8 W, low enough that ganging multiple 1-pole breakers side-by-side doesn't drive a significant temperature rise in the enclosure.
Suitable for indoor panel mounting, not for wet or outdoor locations without an additional enclosure. This is a plain thermal-magnetic breaker for straightforward branch-circuit protection — no auxiliary signaling or remote trip capability built in. UL file MEAB covers the UL listing for the US market.