What this MCCB is and what it does
The Siemens 3VA1120-4EE36-0AA0 is a SENTRON molded case circuit breaker (MCCB) built for line protection in distribution panels. It carries a 20 A continuous rating at 40 °C across all three poles, with a TM220 thermal-magnetic trip unit that handles both overload and short-circuit response without external control wiring. Breaking capacity is the headline here: 121 kA at 240 V AC, 75.6 kA at 415 V, and still 52.5 kA at 440 V. That puts it well above typical fault-current levels for most industrial service-entrance or sub-distribution boards, so you get selectivity headroom without stepping up to a larger frame.
Ratings that matter for panel fit
Rated insulation voltage is 800 V, which covers 480/277 V and 600 V systems with margin. The 20 A rating holds steady from 40 °C through 55 °C, then derates to 19 A at 60–70 °C — useful if the breaker sits near transformers or drives in a warm enclosure. Dimensions are 76.2 mm wide (3 in), 130 mm tall, 70 mm deep — standard 3-pole MCCB footprint for DIN-rail or panel-mount. Front IP40 keeps dust out of the trip-unit compartment; no IP rating on the rear terminals, so plan for finger-safe busbar covers if live parts are exposed. Maximum power loss is 12 W at rated load — negligible for thermal budgeting in most enclosures, but worth noting if you pack multiple breakers in a sealed box.
Lifecycle and sourcing reality
If you're filling a panel originally specified with the 3VA1110-5ED36-0AA0 (a 16 A variant in the same frame), the 3VA1120-4EE36-0AA0 shares the same physical footprint and terminal layout — no rewiring needed, just a higher current rating if the load allows it.
Deployment context
Mounts on DIN rail or direct panel in a standard distribution board. The 3-pole design with TM220 trip means it's a fit for feeder circuits, lighting panels, and small motor branch circuits where a thermal-magnetic curve is acceptable and no electronic trip adjustments are needed.