The Schneider Electric G12E3A16 is a GoPact MCCB 125 — a fixed-mount, 3-pole moulded-case circuit breaker with a TM-D thermal-magnetic trip unit rated 16 A at 40 °C. It is designed for distribution duty (Category A, per EN/IEC 60947-2), meaning it is not intended for motor-starting or high-cycling applications but for protecting cable and bus in a panel. The 15 kA breaking capacity at 415 V AC (E 15 kA 380/415 V AC) covers most commercial and light industrial fault levels.
The thermal element (L) handles overloads; the magnetic element (I) handles short-circuits. Insulation voltage is rated 440 V AC, and operational voltage 415 V AC 50/60 Hz, both per EN/IEC 60947-2. The breaker is suitable for isolation (yes per that standard), so you can use it as a disconnecting means under load. Mechanical durability is 30,000 cycles; electrical durability is 8,000 cycles at rated current and voltage. For a distribution breaker that sees infrequent switching, this is ample.
Mounts on a backplate (not DIN rail) — fixed by screw terminals. The 25 mm connection pitch matches standard busbar and terminal-block layouts. Front connections both top and bottom simplify wiring in a panel.