Siemens SENTRON 5SL6125-6RC is a 1-pole miniature circuit breaker rated 25 A at AC with a B tripping characteristic and 7.5 kA breaking capacity per EN 60898. Mounting position is unrestricted, which simplifies layout in tight cabinets.
The B characteristic is load-specific: it allows short-duration inrush up to 5× rated current (125 A peak) before the magnetic trip engages. This suits resistive loads, lighting, and general-purpose outlets — not motor circuits or transformers that draw higher starting currents (those need C or D curves). The 7.5 kA breaking capacity per EN 60898 certifies that the breaker can safely interrupt a short-circuit fault of up to 7.5 kA at 415 V AC without welding contacts or rupturing the case, which is adequate for most residential and light commercial service-entrance panels. The single-pole construction (1P) switches the line conductor only; neutral is not switched, which is standard for single-phase branch circuits. The maximum operating voltage for single-phase operation is 250 V AC, and for multi-phase operation 440 V AC — confirm the system voltage matches before specifying. This is not a load-break rating — it assumes the breaker is operated as a disconnect under no-load or low-load conditions. For frequent on-load switching, a contactor or switch-disconnect is the correct component. The halogen-free and silicon-free construction is relevant for clean-room or process-industry panels where outgassing from a fault event must not contaminate the environment.
Integration Notes
The 18 mm width (1 MW) and 70 mm installation depth leave room for adjacent breakers and busbar connections. The sealable feature allows the toggle to be locked in the OFF position with a padlock or seal — useful for lockout/tagout during maintenance. Degree of pollution 2 and overvoltage category 3 are standard for fixed-installation distribution boards in dry, non-conductive environments.