Stair light timer switch with optional pre-warning for turning off. Standby loss is only 0.7 watts. Contact switching at zero crossing to protect contacts and lamps, which especially extends the lifespan of energy-saving lamps. The use of a bistable relay ensures that there is no coil loss and no heating even when switched on. After installation, a brief automatic synchronization should be waited for before connecting the switched load to the power supply. Control, supply, and switching voltage is 230V. Glow lamp current up to 50mA, depending on the ignition voltage of the glow lamps. Precise time setting from 1 to 12 minutes with a minute scale. Own permanent light switch with a large rotary switch. For 3-wire circuits with attic lighting, not extendable. Only for retrofitting existing systems. After a power failure, the lighting will turn back on if the time cycle has not yet finished.