Siemens 5SJ6210-6 — 2-pole B-curve MCB for 400 V AC branch circuits
It breaks fault currents up to 6 kA per EN 60898 at 400 V AC, which covers the standard fault-current duty for most commercial and light-industrial final subcircuits in 400/230 V TN systems. The 6 kA rating matches the typical prospective short-circuit current at the distribution board in a building installation — no need to uprate for a standard panel. It trips fast on a short-circuit but avoids nuisance trips on moderate inrush from small motors or capacitive loads.
Terminal capacity and panel fit
The screw terminals accept solid or stranded conductors from 0.75 mm² up to 25 mm², which covers the full range from 1.5 mm² lighting circuits up to 6 or 10 mm² feeder tails. The 70 mm installation depth matches the standard SENTRON 5SJ6 / 5SL6 family footprint — it clips onto a DIN rail and occupies 2 width units (36 mm).
Ambient temperature range is -20 to +45 °C, with periodic excursions to +55 °C at up to 95% humidity. Storage range is wider (-40 to +75 °C), covering shipping and warehouse conditions. Overvoltage category 3 and insulation voltage 440 V AC confirm it is rated for fixed-installation distribution boards where transient overvoltages from the utility side are expected. The mechanical endurance of 20 000 switching cycles is typical for an MCB in a panel that sees occasional manual switching plus fault interruptions.