FI/LS switches (RCBOs) provide personal and property protection as well as protection against electrically ignited fires in accordance with DIN VDE 0100-410 and DIN VDE 0100-530. They ensure the protection of single-phase circuits against overload and short-circuit currents, protection against sinusoidal alternating currents and pulsating currents with smooth residual direct current of up to 10 mA to ground. Additionally, they offer fault protection (protection against indirect contact), additional protection (with IΔn ≤ 30 mA), and fire protection (with I∆n ≤ 300 mA). They have a higher insensitivity to unwanted tripping due to a short-time delay and can detect mixed frequency currents up to 1 kHz. They comply with the product standard IEC/EN 61009-1 (VDE 0664-20). The connection is made directly via the Smissline TP plug-in system, and the external conductor connection can be freely chosen for single-phase devices (L1, L2, or L3).