The Siemens 5SL6420-7BB is a SENTRON miniature circuit breaker (MCB) in a 4-pole (4P) configuration, C-curve tripping characteristic, rated 20 A at 400 V AC. It carries a 6 kA breaking capacity under both EN 60898 and IEC 60947-2 — enough for most residential and light commercial distribution boards where the prospective fault current stays under that threshold. The C-curve means it trips between 5× and 10× In (100–200 A magnetic release), so it handles moderate inrush from motor starters or capacitor banks without nuisance tripping, while still clearing a hard short fast.
Snaps onto standard DIN rail — 4 modular width units (72 mm wide) — and accepts any mounting position. Depth is 76 mm, installation depth 70 mm, so it clears most 80 mm deep enclosures. Rated IP20 with conductors connected, which is standard for panel-mount MCBs; no washdown rating, so keep it inside the cabinet. The housing is halogen-free and silicon-free, a plus for environments sensitive to outgassing (clean rooms, medical, food processing).
Current production — no phase-out notice on record. The 5SL6 series is Siemens' standard residential/infrastructure MCB line, widely specified across Europe and Asia. For a BOM freeze, this part is stable; no PCN or LTB expected in the near term. Sourced to order against an RFQ through independent distribution channels; availability and current pricing confirmed at quote time.
Rated for overvoltage category III and pollution degree 2 — typical for fixed-installation distribution boards. Mechanical service life is 10 000 operating cycles, which is standard for this class. The breaker does not switch the neutral (4P without neutral switching), so it's a straight 4-pole overcurrent protection device for three-phase loads where the neutral is solidly connected. Temperature derating is published: 18.94 A at 40 °C, 18.4 A at 45 °C, 17.24 A at 55 °C — factor that into the panel thermal design if the breaker is in a warm cabinet.