The Siemens 5SY6620-7CC is a 4-pole (3P+N) miniature circuit breaker from the SENTRON 5SY6CC series, rated 20 A with a C tripping curve. The 6 kA breaking capacity at 400 V AC (per EN 60898) tells you it can safely interrupt a fault current up to 6,000 A without welding contacts or cascading upstream; the 5 kA rating under UL 1077 covers North American panel applications. At 20 A and 400 V, this breaker handles branch circuits feeding a handful of motor starters or a lighting subpanel, not a main feed. Mounting is snap-on DIN rail (quick assembly system per the spec), and the 72 mm width (4 width units) fits standard enclosure cutouts. The 76 mm depth leaves clearance behind the rail for wiring — no tight squeeze on a 100 mm deep enclosure. Terminal capacity accepts solid or stranded conductors from 0.75 to 35 mm², so you can land a 6 mm² feed and daisy-chain 2.5 mm² branch tails without adapters.
Installation depth is 70 mm from the DIN rail face; the overall 76 mm depth includes the actuator and terminal overhang. Mounting position is any — horizontal, vertical, or upside-down — so you can orient the breaker to match the busbar or cable entry without derating. The combined terminal (top and bottom) accepts screw-type terminations with a tightening torque of 2.5 to 3.5 N·m, which is typical for 35 mm² lugs. Sealable (yes) means you can lock the toggle with a padlock for lockout/tagout. Ambient temperature range -25 to +55 °C covers most indoor industrial enclosures; storage range -40 to +75 °C is wider for warehouse cycling. The humidity spec (max 95% at 55 °C, derating at higher temps) is typical for unsealed enclosures — no special coating needed for normal plant floor conditions.