A security system utilizes danger sensors (3) and a central unit connected wirelessly to the danger sensors (3). The danger sensors (3) have a communication module (8) which has the same dimensions and same shape for all sensor types, and which is intended to attach the danger sensor (3) to a mounting plate (2). In addition to the communication module (8), the danger sensor (3) contains a detection module (9) where the communication module (8) has a mechanical and electrical/electronic interface with the detection module (9).