This standard contains the specific requirements for construction and assessment of intrinsically safe electrical systems@ type of protection ??i??@ intended for use@ as a whole or in part@ in Class I@ Zone 0@ 1@ or 2@ or Zone 20@ 21@ or 22 hazardous (classified) locations as defined by the National Electrical Code? (NEC)@ ANSI/NFPA 70? . NOTE 1 This standard is intended for use by the designer of the system who may be a manufacturer@ a specialist consultant or a member of the end-user??s staff. This standard supplements and modifies the general requirements of ANSI/ISA-60079-0 and ANSI/ISA-61241-0 and the intrinsic safety standard ANSI/ISA-60079-11 and ANSI/ISA-61241-11. Where a requirement of this standard conflicts with a requirement of ANSI/ISA-60079-0@ ANSI/ISA-60079-11@ ANSI/ISA-61241-0 or ANSI/ISA-61241-11@ the requirement of this standard takes precedence. The installation requirements of Group II or Group III systems designed in accordance with this standard are specified in the National Electrical Code ANSI/NFPA 70