One of the main tasks for smart grid sensors will be the real-time monitoring of electrical components of the Medium Voltage (MV) network, since failures of these components, strongly correlated to their ageing, typically represent a high percentage of outages in an MV distribution network. RSE developed a fi bre optic multisensor prototype for an early detection in MV switchboard of predischarges; these phenomena, on a long term, can give rise to breakdown and consequently to out of service [ 1 ]. One main feature of these predischarge phenomena is their distinctive pattern correlated with both phase and polarity of the applied voltage (50 Hz). Diagnostic analysis of these events generally requires a synchronization between acquired signals and electrical phase of the MV switchboard to assess the degradation of the MV switchboard insulations. Also for the RSE prototype, it was proposed an automated temporization in order to improve its functionality in practical applications. In this work, it was proposed and investigated the feasibility of a fi bre optic “trigger” sensor to be integrated into the developed prototype.