The Schneider Electric GoPact MCCB 125 G12T4F20 is a fixed-mount, 4-pole molded-case circuit breaker with a 20 A thermal-magnetic TM-D trip unit rated at 40 °C.
In a panel that runs hotter, the thermal element picks up earlier — factor the standard IEC 60947-2 derating curve if your enclosure internal ambient exceeds 40 °C. The LI protection profile means thermal overload (L) for sustained overcurrent and magnetic short-circuit (I) for instantaneous fault clearing; there is no ground-fault or short-delay function inside this TM-D unit. At 415 V AC the breaker interrupts 10 kA symmetrical (Icu). The four poles are all protected (4D), with the neutral on the left. Neutral protection is set at 1 x Ir, so the neutral conductor is treated identically to the phases for overload — appropriate for 4-wire systems where harmonic content can load the neutral. The 25 mm connection pitch and front-facing screw terminals (upside and downside) simplify bus-bar and cable routing in a standard backplate-mounted panel.