A thermal relay is provided comprising, in a first cavity of a case, bi-metallic strips through which pass currents of a multi-phase network feeding a load through an electromagnetic contactor and, in a second cavity, an electromagnetic sub-assembly including break and signalling switches whose mobile contacts have pivoting axes and actuating points cooperating with a common piece, the whole forming a deformable parallelogram. The second cavity also contains toggle transmission means between the bi-metallic strips and said common piece as well as means for selecting the mode of operation of the switches. Toggle springs are associated with said mobile contacts.