Combined terminal top and bottom accept the same conductor range — no need to stock separate feed-through lugs for the line and load side.
Breaking capacity and standard compliance
Energy limitation class 3 means the let-through energy is low enough to protect downstream cabling and connected loads under most fault conditions — relevant for coordinating with an upstream RCD or main breaker.
Thermal derating and ambient range
Rated 50 A at 35 °C ambient. At 40 °C the continuous current drops to 48 A, at 45 °C to 47 A, and at 55 °C to 44.9 A. The full derating curve runs to 60 °C where the breaker carries 43.8 A. Minimum ambient is -40 °C; maximum is 75 °C. Not intended for high-inrush transformer or motor starting loads; those need C or D curves.
Current production stage — no end-of-life notice on record. The 5SY4 series is Siemens' standard 4-pole B-curve offering; no official successor announced.