What this breaker is for
The C16F4TM125D1 is a 4-pole ComPacT NSX DC PV circuit breaker from Schneider Electric — a thermal-magnetic unit built specifically for photovoltaic DC strings and combiner boxes. Rated 125 A at 40 °C with a 10 kA Icu breaking capacity at 1000 V DC (four poles in series, per IEC 60947-2), it isolates and protects PV arrays against overload and short-circuit faults. The TM-DC trip unit gives you thermal (L) overload protection and magnetic (I) short-circuit protection, both tuned for the DC current profile of solar generation.
Four poles in series means all four poles interrupt together, giving you full isolation on both the positive and negative conductors of a bipolar DC system. The thermal-magnetic trip acts fast on high currents (magnetic) and handles sustained overloads (thermal) — no external control power needed.
Fixed-mount design, backplate-mounted with a 35 mm connection pitch. Rated IP40 and IK07 — sealed against tools and small solids, but not for washdown; it lives inside the cabinet, not out in the weather. Pollution degree 3 means it handles conductive dust and condensation typical in industrial solar fields.