The invention provides a system for locating a fault in a conductor such, as a break in a buried wire. The system includes a first conductor portion and a second conductor portion separated from each other by the fault, the system including a field generator, having: a first connection connectable to the first conductor portion, a first signal generator configured to apply a first oscillating signal between the first connection and an earth, the first oscillating signal having a frequency of between 1 and 20 kHz, and a mobile detector for detecting an electric field produced by the application of the first oscillating signal to the first conductor portion, the detector including a capacitive sensor element, a signal processor to which the sensor element is connected and having an output, and a monitor receiving the output from the signal processor and providing a signal to an operator to indicate the position of the fault.