The Siemens 5SY1708-4 is a SENTRON device protection switch — a single-pole unit with an integrated auxiliary switch (1P+AS) that trips on the F2 characteristic. Rated 8 A at AC, it's built to protect a single load circuit in a control panel, with the auxiliary contact feeding a status signal back to a PLC or indicator.
Mounts horizontal or vertical — no restriction. The IP20 finger-safe terminals mean you can work live in a panel without a shock risk, as long as the front is closed.
Temperature derating — the real current rating
The 8 A rating holds up to 35 °C ambient. Above that, it derates: 7.33 A at 40 °C, 7.13 A at 45 °C, 6.91 A at 50 °C, 6.69 A at 55 °C, and 6.46 A at 60 °C.
Built to IEC / DIN EN 60934 and UL1077 — so it's accepted in both IEC and North American panels. Halogen-free and silicon-free construction, which matters in clean-room or high-reliability environments where outgassing can't happen. The sealable design lets you lock the toggle position after commissioning, preventing unauthorized resets.