IEC 60079-25:2010 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 locations in which the use of Group I, II or III apparatus is required. This standard supplements and modifies the general requirements of IEC 60079-0 and the intrinsic safety standard IEC 60079-11. Where a requirement of this standard conflicts with a requirement of IEC 60079-0 or IEC 60079-11, the requirement of this standard takes precedence. This standard supplements IEC 60079-11, the requirements of which apply to electrical apparatus used in intrinsically safe electrical systems. The installation requirements of Group II or Group III systems designed in accordance with this standard are specified in IEC 60079-14. The significant changes with respect to the previous edition are: - extension of the scope from Group II to Groups I, II and III; - introduction of level of protection 'ic'; - addition of requirements for cables and multi-core cables; - reference to IEC 60079-11 regarding the termination of intrinsically safe circuits; - requirements for the assessment of an expanded and clarified intrinsically safe system regarding level of protection 'ic', simple apparatus and faults in multi-core cables; - introduction of predefined systems and merging of the system requirements for FISCO from IEC 60079-27; - addition of requirements for simple intrinsically safe systems containing both lumped inductance and lumped capacitance; - addition of a method for testing the electrical parameters of cables; - additional information for the use of simple apparatus in systems.