The device comprises at least a first part intended to detect an electrical fault occurring in a network and a second part comprising at least one switch connecting the network to a power supply source, the first part comprising at least one reflectometry detection system capable of being coupled with the network, the system detecting and analyzing the impedance changes occurring in the network, a signal being sent by the system to trigger the opening of the switch when a detected impedance change is considered by the system to be an electrical fault.