Siemens 5SL3210-7MB — 2-pole C-curve 10 A MCB for 400 V distribution
The Siemens 5SL3210-7MB is a SENTRON miniature circuit breaker rated 10 A with a C tripping characteristic, designed for 400 V AC multi-phase operation. Its 4.5 kA breaking capacity per EN 60898 is sized for residential and infrastructure final circuits where fault current stays below that threshold — typical for TN and TT systems in EU-standard distribution boards.
Two-pole design occupies 2 modular width units (36 mm) on DIN rail, with a 76 mm depth that clears standard 80 mm deep enclosures. Snap-on mounting in any position — no derating needed for horizontal or inverted orientation. IP20 with conductors connected; install inside a distribution board or panel with a door or cover. Sealable design allows lockout-tagout compliance on the toggle.
Breaking capacity — what the 4.5 kA rating means for your BOM
The 4.5 kA rating per EN 60898 at 400 V AC is the maximum prospective short-circuit current the breaker can safely interrupt. For a panel fed by a 100 kVA transformer with ~5% impedance, the available fault current at the sub-distribution board is typically under 3 kA — this breaker has headroom. If your site has a larger transformer or a fault level above 4.5 kA, step up to the 10 kA rated 5SL4363-7 (3-pole, same SENTRON family) for the same C-curve protection. The 5SL3210-7MB carries energy limitation class 3, meaning it limits let-through energy on a fault to keep downstream equipment damage minimal.