Siemens 5SL1204-7MB SENTRON MCB — 2-pole C-curve 4 A, 3 kA
The Siemens 5SL1204-7MB is a 2-pole miniature circuit breaker from the SENTRON series, rated at 4 A with a C tripping characteristic. It provides overcurrent and short-circuit protection for final circuits in residential and infrastructure installations, per IEC 60947-2 with a 3 kA breaking capacity at 230/400 V AC, 50/60 Hz. The C-curve trips between 5 and 10 times rated current (20–40 A), making it suitable for circuits with moderate inrush — lighting banks, general-purpose socket outlets, and small motor loads where the starting surge stays within that window. Occupying 2 modular width units (36 mm) on a DIN rail, with a depth of 76 mm and installation depth of 70 mm, it fits standard distribution boards.
Rated operational voltage: 230 V AC single-phase (253 V max) or 400 V AC multi-phase (440 V max). The 50/60 Hz frequency range covers standard mains supplies globally. For DC applications, the maximum DC voltage is 72 V — this is not a general-purpose DC breaker for higher voltages. For residential panels typically fed by a 6 kA or 10 kA upstream breaker, this 3 kA unit is suited for sub-distribution or final circuits where the fault level is known to be lower — always confirm the available fault current at the breaker location. Mechanical service life: 4,000 operating cycles typical.
Halogen-free and silicon-free construction.