Communication system for controlling electrical loads

The system has a control device (1) attached to a phase conductor (L) of a supply voltage source (4). Load extension modules (3.1, 3.2, 3.m) are connected between the phase conductor and a load line (L'). The load extension modules are connected with the control device by a control line (S). Supply current is transferred from the voltage source to load modules (2.1, 2.2, 2.n) during an energy transmission time window and not during a communication time window. The energy transmission time window occurs periodic to a supply voltage.