Communication bus having at least one pair of communication lines designed to be connected in series respectively to conductors of a main communication bus designed to be connected to communicating devices of at least one electric panel. Said communication bus comprises at least two branched outputs each having at least two branch lines, said branch lines respectively having a first end connected to a communication line and having a second end designed for connection of the communicating devices. The communication lines are etched on a first conducting layer of a printed circuit, and the branch lines are etched on a second conducting layer of said printed circuit. The communication lines are separated from one another by a distance.