Bus device for a bus system for building installation and method for operating a bus device for the bus system of a building installation

The bus device (3) has bus coupler (10) for coupling the bus device to bus (2) e.g. KNX bus of bus system (1). A power supply (11) is provided to supply power to application module (20). A conductive connection (12) is provided between the application module and the power supply. An activation unit (13) is provided for closing and opening (14) the conductive connection based on generated external signal. The application module is provided with sensing unit that is provided with light sensor, temperature sensor, motor sensor or acoustic sensor. An independent claim is included for a method for operating bus device for bus system.