Describes the construction and testing of intrinsically safe apparatus intended for use in an explosive atmosphere and for associated apparatus, which is intended for connection to intrinsically safe circuits which enter such atmospheres.

This part of IEC60079 specifies the construction and testing of intrinsically safe apparatus intended for use in an explosive atmosphere and for associated apparatus, which is intended for connection to intrinsically safe circuits which enter such atmospheres. This type of protection is applicable to electrical equipment in which the electrical circuits themselves are incapable of causing an explosion in the surrounding explosive atmospheres. This standard is also applicable to electrical equipment or parts of electrical equipment located outside the explosive atmosphere or protected by another Type of Protection listed in IEC60079-0, where the intrinsic safety of the electrical circuits in the explosive atmosphere may depend upon the design and construction of such electrical equipment or parts of such electrical equipment. The electrical circuits exposed to the explosive atmosphere are evaluated for use in such an atmosphere by applying this standard. The requirements for intrinsically safe systems are provided in IEC60079-25. This standard supplements and modifies the general requirements of IEC60079-0, except as indicated in Table1. Where a requirement of this standard conflicts with a requirement of IEC60079-0, the requirements of this standard shall take precedence. If requirements in this standard are applicable to both intrinsically safe apparatus and associated apparatus the term “apparatus?? is used throughout the standard. This standard is for electrical equipment only; therefore the term “equipment?? used in the standard always means “electrical equipment??. If associated apparatus is placed in the explosive atmosphere, it shall be protected by an appropriate Type of Protection listed in IEC60079-0, and then the requirements of that method of protection together with the relevant parts of IEC60079-0 also apply to the associated apparatus. Table 1 Applicability of specific clauses of IEC60079-0 Clause or subclause of IEC60079-0 IEC60079-0 clause application to IEC60079-11 Intrinsically safe apparatus Associated apparatus Ed. 5.0 (2007) (informative) Ed. 6.0 (2011) (informative) Clause / Subclause title (normative) Group I and Group II Group III 1 1 Scope Applies Applies Applies 2 2 Normative references Applies Applies Applies 3 3 Terms and definitions Applies Applies Applies 4 4 Equipment grouping Applies Applies Applies 4.1 4.1 Group I Applies Excluded Applies 4.2 4.2 Group II Applies Excluded Applies 4.3 4.3 Group III Excluded Applies Applies 4.4 4.4 Equipment for a particular explosive atmosphere Applies Applies Applies 5.1 5.1 Environmental influences Applies Applies Applies 5.1.1 5.1.1 Ambient temperature Applies Applies Applies 5.1.2 5.1.2 External source of heating or cooling Applies Applies Applies 5.2 5.2 Service temperature Applies Applies Applies 5.3.1 5.3.1 Determination of maximum surface temperature Applies Applies Excluded 5.3.2.1 5.3.2.1 Group I electrical equipment Applies Excluded Excluded 5.3.2.2 5.3.2.2 Group II electrical equipment Applies Excluded Excluded 5.3.2.3 5.3.2.3 Group III electrical equipment Excluded Applies Excluded 5.3.3 5.3.3 Small component temperature for Group I or Group II electrical equipment Applies Excluded Excluded 6.1 6.1 General Applies Applies Applies 6.2 6.2 Mechanical strength of equipment Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 6.3 6.3 Opening times Excluded Excluded Excluded 6.4 6.4 Circulating currents in enclosures (e.g. of large electrical machines) Excluded Excluded Excluded 6.5 6.5 Gasket retention Excluded except when 6.1.2.3a)is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 6.6 6.6 Electromagnetic and ultrasonic radiating equipment Applies Applies Excluded 7.1.1 7.1.1 Applicability Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 7.1.2 7.1.2.1 Specification of materials Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 7.1.3 7.1.2.2 Plastic materials Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 7.1.4 7.1.2.3 Elastomers Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 7.2 7.2 Thermal endurance Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 7.3 7.3 Resistance to light Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 7.4 7.4 Electrostatic charges on external non-metallic materials Applies Applies Excluded NR 7.5 Accessible metal parts Applies Applies Excluded 7.5 NR Threaded holes Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 8.1 8.1 Material composition Applies Applies Excluded 8.1.1 8.2 Group I Applies Excluded Excluded 8.1.2 8.3 Group II Applies Excluded Excluded 8.1.3 8.4 Group III Excluded Applies Excluded 8.2 NR Threaded holes Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 9 9 Fasteners Excluded Excluded Excluded 10 10 Interlocking devices Excluded Excluded Excluded 11 11 Bushings Excluded Excluded Excluded 12 12 Materials used for cementing Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 13 13 Ex Components Applies Applies Applies 14 14 Connection facilities and termination compartments Excluded Excluded Excluded 15 15 Connection facilities for earthing or bonding conductors Excluded Excluded Excluded 16 16 Entries into enclosures Excluded except when 6.1.2.3a) is applied Excluded except when 6.1.3 a) is applied. Excluded except when 6.1.2.3a) is applied 17 17 Supplementary requirements for rotating machines Excluded Excluded Excluded 18 18 Supplementary requirements for switchgear Excluded Excluded Excluded 19 19 Supplementary requirements for fuses Excluded Excluded Excluded 20 20 Supplementary requirements for plugs, socket outlets and connectors Excluded Excluded Excluded