What this 4-pole B-curve 20 A MCB covers
Panel fit and wiring constraints
Four poles means four width units on the DIN rail — 70 mm deep, same as the rest of the 5SJ6 family. Terminals accept solid or stranded copper from 0.75 mm² up to 25 mm², which covers most branch-circuit wiring from 1.5 mm² lighting circuits up to 6 mm² or 10 mm² feeders.
Rated for ambient temperatures from -20 °C to +45 °C, with periodic excursions to +55 °C at up to 95% humidity. Storage range is wider at -40 °C to +75 °C. The mechanical endurance is 20 000 switching cycles typical. Vibration resistance is tested to IEC 60068-2-6 at 50 m/s² from 25 to 150 Hz and 60 m/s² from 10 to 150 Hz — enough for panel-mounted use in industrial machinery but not for direct mounting on a high-vibration engine block.
DC rating and insulation coordination
The DC side is rated for 60 V maximum — useful for 48 V DC control circuits or battery-backed loads, but not for higher-voltage DC strings. Insulation voltage is 440 V AC, overvoltage category III, which is typical for fixed-installation distribution boards downstream of the main panel. Energy limiting class 3 means it restricts let-through energy in a fault, aiding downstream device protection.