The Siemens 5SL6240-6 is a 2-pole SENTRON miniature circuit breaker from the 5SL6 series, rated 40 A with a B tripping characteristic and a breaking capacity of 6 kA per EN 60898 at 400 V AC. This is the standard MCB for residential and infrastructure branch-circuit protection — think final subcircuits feeding general-purpose socket outlets or lighting in a panelboard. The B-curve (3–5× In) means it trips fast on moderate overloads, so it pairs with resistive and light inductive loads where inrush isn't extreme. At 2 width units (36 mm wide), it occupies two standard DIN-rail slots.
What the ratings mean for fit
The 40 A rating is the continuous current the breaker carries without tripping at 30 °C ambient. The B-curve (3–5× In) determines the magnetic trip threshold: between 120 A and 200 A instantaneous. That's appropriate for general-purpose circuits feeding multiple outlets or lighting — not for motor circuits where higher inrush (C or D curve) would be needed to avoid nuisance trips. The 6 kA breaking capacity per EN 60898 is the maximum prospective short-circuit current the breaker can safely interrupt at 400 V AC. In a domestic or light commercial distribution board this is usually sufficient; if your fault level exceeds 6 kA at the point of installation, you'd need a higher-rated device upstream or a current-limiting backup fuse. The 2-pole configuration (switching both line and neutral, though neutral is not switched separately per) fits single-phase or split-phase circuits where both conductors need overcurrent protection. Rated voltage is 400 V AC between phases, with a maximum of 440 V in multi-phase operation. The IP20 rating with connected conductors means the breaker is protected against finger contact when installed in an enclosure — standard for distribution boards and consumer units.
Lifecycle and sourcing reality
For a BOM line that calls out this exact order code, the fit is confirmed by the 40 A B-curve 2-pole configuration. Sourcing is handled by quoting against an RFQ — availability and current pricing are confirmed at the time of quote through independent distribution channels.
Deployment context
The breaker snaps onto a standard 35 mm DIN rail per EN 60715, occupying 36 mm (2 width units). Terminal capacity accepts 0.75 mm² to 25 mm² conductors, so it handles both final-circuit wiring and larger feeder tails. Installation depth is 70 mm behind the panel surface. Mounting position is any — no derating required for horizontal orientation. The sealable design allows the installer to lock the toggle position for tamper resistance in accessible locations.