An electrical installation for an electrical system for trace heating a fluid transport pipe (8) made of metal, at least one polyphase circuit having three main electric cables (6-1, 6-4, and 6-7) in a star connection, and one additional electric cable (6-2, 6-3, 6-5, 6-6, 6-8, and 6-9), the main cables and the additional cable positioned around the pipe and connected at the pipeline end to a common connection ring (10) forming a point of zero electric potential, and detector for detecting a failure, if any, of the polyphase circuit to identify a failed main cable in order to replace it with the additional cable.