The utility model relates to an electric field, name are warning switch board, including the cabinet body, there is electrical component inside the cabinet body, it has warning sign to bond at the external face of cabinet, warning sign be the thermosensitive luminescence sign, install the pipeline that has air exhaust device in the centre in addition inside the cabinet body, pipeline one end is seted up in electric side, and the back that belongs to the cabinet body at warning sign is seted up to the pipeline other end. Still set up the temperature detect device in the pipeline, alarm device is still connected to the temperature detect device. More striking when such switch board has high temperature, the obvious advantage of a certain part high temperature time warning especially.