A power supply line is divided into a plurality of sections by switching devices each having an associated measurement device that detects a current signal at a measurement point at the respective switching device. The current signal is sampled to form current sample values, and a current measurement variable is determined. Each measurement device forms a delta current value (difference between an instantaneous current and a prior measurement), compares the delta current value with a current threshold value and identifies a jump in current when the delta current value overshoots the threshold. The measurement device, upon identifying a current jump, sends a status message indicating the jump. A fault location device identifies a fault on that section of the power supply line delimited by a switching device that has identified a jump and one that has not identified a jump in current.