Fault detection system for a direct electrical heating (DEH) cable for a subsea pipeline , the system comprising: - a first conductor having a first end and a second end ; - a second conductor having a first end and a second end ; a first current sensing device and a second current sensing device , where said first ends are both connected to a power supply system provided at a first position (X1); where the second end of the second conductor is in use connected to the DEH cable at a second position (X2) proximal to said first position (X1); where the DEH cable is electrically connected to the pipeline at a third position (X3) distal to the first position (X1); wherein the second end of the first conductor is in use connected to the pipeline , wherein the system comprises a fiber optic cable connected between the second current sensing device and a signal processing device for transferring the signal S2 provided by the second current sensing device to the signal processing device the system also comprising - its first current sensing device configured to provide a signal S1 representative of the current into or out from the power supply system ; - its second current sensing device configured to provide in use a signal S2 representative of the current in the DEH cable at the third position (X3); - a signal processing device configured to compare the signal S2 representing the current in the DEH cable at the third position (X3) with the signal S1 representing the current into or out from the power supply system characterized in that : said second current sensing device is a fiber optic current sensor (FOCS) provided in use circumferentially around the DEH cable , where the fiber optic current sensor (FOCS) is optically connected to the fiber optic cable . - a first conductor having a first end and a second end ; - a second conductor having a first end and a second end ; a first current sensing device and a second current sensing device , where said first ends are both connected to a power supply system provided at a first position (X1); where the second end of the second conductor is in use connected to the DEH cable at a second position (X2) proximal to said first position (X1); where the DEH cable is electrically connected to the pipeline at a third position (X3) distal to the first position (X1); wherein the second end of the first conductor is in use connected to the pipeline , wherein the system comprises a fiber optic cable connected between the second current sensing device and a signal processing device for transferring the signal S2 provided by the second current sensing device to the signal processing device the system also comprising - its first current sensing device configured to provide a signal S1 representative of the current into or out from the power supply system ; - its second current sensing device configured to provide in use a signal S2 representative of the current in the DEH cable at the third position (X3); - a signal processing device configured to compare the signal S2 representing the current in the DEH cable at the third position (X3) with the signal S1 representing the current into or out from the power supply system characterized in that : <EOS>