Flush-mounted staircase light time switch, electronic, push-button can be connected. Suitable for retrofitting and new installations. Zero-crossing switching protects the relay contact and light source, extending the service life of the light source. Push-button input with electronic overload protection. Automatic 3- or 4-wire detection (4-wire with connection for floor lighting; 3-wire no longer permitted for new installations). High speed accuracy. Can be switched on immediately.