Presence detector for ceiling mounting indoors. The sensor module detects moving heat sources (e.g. people) in an adjustable detection range and starts a staircase lighting time. For ohmic, inductive and capacitive loads such as light bulbs, energy-saving bulbs, low-voltage halogen lighting with conventional transformers, electronic transformers, fluorescent lamps. The sensor module has a light sensor with an adjustable brightness threshold, so the lighting is only switched on below a certain brightness threshold. Thanks to the presence function, the sensor module can switch off the lighting despite a person being present if there is sufficient natural light. For mounting in a size 60 flush-fitted socket or in the surface-mounted housing available as an accessory.