The Siemens 5SL3406-7 is a 4-pole miniature circuit breaker from the SENTRON 5SL3 family, rated 6 A with a C tripping characteristic at 400 V AC. It breaks 4.5 kA per EN 60898 and IEC 60947-2, which covers most residential and light commercial service-entrance faults. The 4-pole form factor (4 width units, 72 mm wide) means it switches all three phases plus neutral — though note the neutral pole is not switched on this variant. Snaps onto standard DIN rail, accepts solid or stranded copper from 0.75 mm² up to 25 mm², and the screw terminals torque to 2.5–3 N·m. The IP20 rating (with conductors connected) is typical for enclosed panel mount — no washdown rating here, so keep it behind a gland plate.
C-curve and 6 A — what that means on the line
The C-curve trips at 5 to 10 times rated current (30–60 A magnetic trip), which suits moderate inrush loads like small motor starters, lighting banks, and transformer primaries. At 6 A it's sized for branch circuits pulling around 1.5 kW on a 400 V three-phase system. The 4.5 kA SCCR at 400 V is the standard domestic/infrastructure level — fine for most distribution boards, but check your available fault current if you're near a large transformer.
The 72 mm width (4 modules) occupies standard DIN space — factor that into your fill count. Ambient operating range is -25 to +45 °C, with periodic excursions to +55 °C at up to 95% humidity.