This standard contains the details of apparatus, systems and installation practice for use with the Fieldbus Intrinsically Safe Concept (FISCO) for installation and use in Class I, Zones 0 and 1 and the Fieldbus Non-Incendive Concept (FNICO) for installation and use in Class I, Zone 2. It 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 requirements of FISCO and FNICO apparatus and systems are determined by ANSI/ISA-60079-11 and ANSI/ISA-60079-15, except as modified by this standard. Part of a Fieldbus device may be protected by any of the methods of explosion protection listed in ANSI/ISA-60079-0 suitable for the application. In these circumstances, the requirements of this standard apply only to that part of the apparatus directly connected to the intrinsically safe or non-incendive trunk or spurs.

NOTE 1 Certification to the FISCO requirements does not prevent apparatus also being certified and marked to ANSI/ISA-60079-11 in the conventional manner so that they may be used in other systems. Some apparatus certified before this standard was published but not necessarily complying with the electrical parameters of this standard may be marked ‘Suitable for FISCO systems'. This apparatus may be accepted in a FISCO system, if the comparison of the electrical parameters U_o, I_o, P_o, with U_i, I_i, P_i, demonstrate compatibility with the remainder of the system, and all the other requirements of this standard are met.

NOTE 2 A typical system is illustrated in Clause 10.

NOTE 3 Generally, FNICO systems are intended for use in Zone 2 locations. FISCO systems are predominantly intended for use in Zone 1 and 2 locations, but may enter Zone 0 locations if specifically permitted to do so by the Control Drawing.

NOTE 4 This standard uses the IEC designations (Uo, Io, Po etc.) for electrical parameters through out, however, either the ISA markings, the IEC markings, or both, as shown in Table 12.3, of ANSI/ISA-60079-11 may be used to designate electrical circuit parameters on the apparatus and in the installation documents and control drawing.

NOTE 5 This standard is for apparatus for use in a Class I Zone 0, 1 or 2 hazardous (classified) location but the principles contained may be used for examination of apparatus for use in Class I, Divisions 1 and 2 as permitted by 501.5 of the National Electrical Code ANSI/NFPA 70.