Contains the details of apparatus, systems and installation practice for use with the Fieldbus intrinsically safe concept (FISCO) and is based on the concepts of Manchester encoded, bus powered systems designed in accordance with IEC 61158-2 which is the physical layer standard for Fieldbus installations. The constructional and installation requirements of FISCO apparatus and systems are determined by IEC 60079-11, IEC 60079-25 and IEC 60079-14, except as modified by this specification.