This device belongs to the Vigilohm range designed to monitor ungrounded/IT electrical networks at feeder level, in accordance to installation and products standards. The mobile fault locating kit comes in the form of a case containing 2 devices and 3 probes. The first device is a locating signal generator, XGR, that need to be supplied with 220V AC to 240V AC. The second device is a locating signal receiver XRM. And three tong-type current probes: XP15, XP50 and XP100. The kit is used on LV IT systems (i.e. installations with an unearthed or impedance-earthed neutral). It enables fault locating on AC installations 50 to 400 Hz or DC installations. It is used mainly with insulation monitoring devices that inject DC currents (IM9) or too small AC current (IM10,IM20). The XGR generator injects a 2.5 Hz AC voltage between the installation and the earth. Thereby creating a leakage current which passes through the installation insulation impedance. The XRM mobile receiver is associated with one of the three tong-type probes, XP15, XP50 or XP100, and detects this leakage current at 2.5 Hz. It displays a value between 1 and 19 according to the current passing through the probe, thus detecting the leakage current. Three current probes are available, the XP15, XP50 and the XP100, for cables with diameters up to 12, 50 and 100 mm respectively. Older probe models are not compatible with the XRM.