Four poles cover three-phase plus neutral switching, common in 400 V distribution panels where all conductors need overcurrent and short-circuit protection. The 50 A rating matches a 50 A busbar or feeder tap; don't oversize the upstream protective device beyond the breaker's rated breaking capacity.
Siemens lists the 5SL6450-8CC as Active (current production). RoHS compliance is confirmed since 01-06-13; REACH candidate-list information is available on request. No end-of-life notice or successor part is published.
Integration notes
Snap-on mount to standard 35 mm DIN rail. The 4-pole width occupies 4 module spaces (72 mm at 18 mm per pole). Wire termination accepts copper conductors up to 25 mm² for the line and load terminals. No auxiliary contact slot on this basic device; if remote signalling is needed, specify the 5SL series auxiliary switch separately.