What the 125 A TM-D trip and 36 kA breaking capacity mean for your panel
The C16F3TM125C is a 3-pole ComPacT NSX160F moulded-case circuit breaker from Schneider Electric's current-production ComPacT NSX family, fitted with a TM-D thermal-magnetic trip unit rated 125 A at 50 °C. The TM-D gives you fixed thermal (overload) and fixed magnetic (short-circuit) protection curves — no interchangeable rating plugs, no electronic adjustment. For a distribution board or feeder circuit where the load is known and stable, that is a simpler, more robust choice than an electronic Micrologic trip. The F breaking-capacity code delivers 36 kA Icu at 380/415 V AC (50/60 Hz) per IEC 60947-2, stepping up to 85 kA at 220/240 V and down to 8 kA at 690 V. At 690 V the 8 kA Icu still covers most 690 V distribution applications, but verify it against your transformer's through-fault capability. The breaker is rated Category A (no intentional short-time delay). It clears fast on magnetic pickup — good for branch protection where you want instant trip on a hard fault.
Lifecycle and sourcing — current production, no LTB looming
The C16F3TM125C carries a current lifecycle stage from Schneider. No end-of-life notice, no last-time-buy date. It is a standard catalogue item in the ComPacT NSX range.
Mounting and integration — backplate mount, front connections, 105 mm wide
The 105 mm width and 161 mm height fit the standard ComPacT NSX footprint. Both line and load connections are front-accessible, with a 35 mm connection pitch. That keeps the wiring plane clean and the busbar runs straight. The toggle handle protrudes forward; account for the 86 mm depth plus handle swing when sizing the enclosure depth. IP40 front face, IK07 impact resistance. Suitable for indoor distribution panels where occasional tool drops or panel-door bumps are the norm.
Electrical durability and power dissipation — plan for the thermal budget
Rated for 40,000 mechanical cycles and 20,000 electrical cycles at rated current (440 V, In). At half load (In/2) that climbs to 40,000 electrical cycles. For a frequently switched feeder — say a compressor or pump starting once per hour — that is a 5–10 year service life before contact wear becomes a consideration. Power dissipation is 10.78 W per pole, so roughly 32 W total at rated load. That heat has to leave the enclosure; factor it into your panel thermal calculation, especially if the MCCB is mounted in a sealed stainless steel box.