Abstract: A system for detecting presences has modules or devices equipped with electronic circuits for the transmission and reception of binary messages by carrier current passing through the normal domestic electric network. The devices, connected to the electric network by an incorporated plug, are in addition equipped with actuators for the control (command) of the electric power equipment in order to intercommunicate at an equivalent rank level. This system consisting of an ensemble of several devices of the above-mentioned kind associated with devices having presence-detecting characteristics is capable of carrying out the function of an anti-intrusion alarm installation.