Abstract: The invention relates to a system for monitoring a fiber optic cable (2) connected between optical signal transmitting (TX) and receiving (RX) equipment, and comprising first (3) and second (4) electro-optical devices for measuring optical power being both connected to a central control unit (14) over a bus (13) and permanently connected to the beginning and the end, respectively, of the fiber optic cable (2), at said transmitting (TX) and receiving (RX) equipment.The invention also relates to a compact electro-optical device (3) for measuring the operating optical power (P) of a fiber optic cable (2), having an optic input (5) and optic output (7), as well as an electric input (9) and electric output (11) and being of the type which comprises an optical power measuring circuit (20) having an input (19) connected to the optic input (5) and an output (21) connected to the electric output (11).