Stair light delay switch, 1 normally closed contact not potential-free 16A/250V AC, suitable for incandescent lamps up to 2000W, with a fallback delay and a pre-warning before switching off, as well as an optional permanent light function via a button. Also suitable for energy-saving lamps (ESL) up to 200 watts. Bidirectional. Standby loss is only 0.2 watts. Rail-mounted device for installation on a mounting rail. Connection to the Eltako RS485 bus. Cross-wiring of bus and power supply with a jumper. Switching voltage 230V. Contact switching at zero crossing to protect the contacts and consumers. In the event of a power failure, the switching state is maintained. When power is restored, the timing begins, and the device will switch off at the end of this period. In addition to the bus control input, this stair light delay switch can also be locally controlled with a conventional 230V control button. Glow lamp current up to 5mA, depending on the ignition voltage of the glow lamps. The upper rotary switch LRN is needed for the learning process. After that, the fallback delay can be set from 1 to 30 minutes. The middle rotary switch is used in the LRN position to learn radio buttons and/or radio motion brightness sensors (FBH), including one or more central control buttons. After that, the desired function of this stair light delay switch can be selected: NLZ = delay switch with adjustable response delay. The LED under the upper rotary switch accompanies the learning process according to the operating instructions and indicates control commands during operation by briefly flashing.