Abstract: A current collector comprises one or more Fibre Bragg Grating sensors mounted on or in the current collector. Such collector can be used in a system in which:—i) detector means in the collector indicates a current collector condition and/or damage signal at a predetermined level likely to cause damage to the overhead conductor; ii) locating means operatively connected to said detector means generate a signal indicating the location of the pantograph on the overhead conductor at which the current collector damage signal was generated. Such a system can monitor not only impact forces on the collector, but also contact force and collector temperature.