An intake duct 1 is provided, particularly for taking air in an internal combustion engine, notably the engine of an automobile. The mold is made by manufacturing a pattern master on which a fine pattern is formed. Reinforcement with glass fiber and jute fiber modifies the compositions for moulding the trays. The circuit electrically connects the ground conductor to the plurality of arcuate ground bus bars for electrically and mechanically mounting a corresponding surge suppressor module, in order to provide a common ground connection thereto.