UL 60079-11:2026

Explosive Atmospheres - Part 11: Equipment Protection by Intrinsic Safety - Published Date: January 30, 2026

This part of IEC 60079 specifies the construction and testing of intrinsically safe apparatus intended for use in explosive atmospheres, and for associated apparatus which is intended for connection to intrinsically safe circuits which enter such atmospheres.  Replace "part of IEC 60079" with "standard".  This Type of Protection is applicable to electrical equipment in which the electrical circuits themselves are incapable of causing ignition of a surrounding explosive atmosphere. This includes electrical equipment which contains circuits that are intrinsically safe only under certain conditions, for example under battery supply with mains supply removed.  This document 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 IEC 60079-0, 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 assessed for use in such atmospheres by applying this document.  Replace "IEC 60079-0" with "UL 60079-0 and CSA C22.2 No. 60079-0".  This document applies to sensors connected to intrinsically safe circuits but does not apply to the protection of catalytic elements for Group IIC or Group IIB + H2.  This document does not apply to Ex Equipment cable glands.  The requirements for intrinsically safe systems are provided in IEC 60079-25.  Replace "IEC 60079-25" with "UL 60079-25 and CSA C22.2 No. 60079-25".  This document supplements and modifies the general requirements of IEC 60079-0, except as indicated in . Where a requirement of this document conflicts with a requirement of IEC 60079-0, the requirement of this document takes precedence.  Replace references "IEC 60079-0" with "UL 60079-0 and CSA C22.2 No. 60079-0".  Unless otherwise stated, the requirements in this document are applicable to both intrinsically safe apparatus and associated apparatus, and the generic term "apparatus" is used throughout the standard.  As this document applies only to electrical equipment, the term "equipment" used in the standard always means "electrical equipment".  This document applies to apparatus for use under the atmospheric conditions of IEC 60079-0 with additional requirements for use at extended atmospheric pressures in the range from 60 kPa (0,6 bar), up to 110 kPa (1,1 bar).  Replace "IEC 60079-0" with "UL 60079-0 and CSA C22.2 No. 60079-0".  Where references are made to other IEC, IEC/IEEE, ISO, or ISO/IEC standards, the referenced requirements found in these standards apply as modified by any applicable Canadian National Differences or US National Differences for the standard (see Clause 2).  Clause or subclause of IEC 60079-0  IEC 60079-0 clause application to IEC 60079-11  Intrinsically safe apparatus  Associated apparatus  Ed.6  (2011)  Ed.7  (2017)  Clause / Subclause  title  Group I and Group II  Group III  (informative)  (informative)  (normative)  3  3  Terms and definitions  Applies  Applies  Applies  4  4  Equipment grouping  Applies  Applies  Applies  5  5  Temperatures  5.1  5.1  Environmental influences  Applies  Applies  Applies  5.2  5.2  Service temperature  Applies  Applies  Applies  5.3  5.3  Maximum surface temperature  Applies  Applies  Excluded  6  6  Requirements for all electrical apparatus  6.1  6.1  General  Applies  Applies  Applies  6.2  6.2  Mechanical strength  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  6.3  6.3  Opening times  Excluded  Excluded  Excluded  6.4  6.4  Circulating currents in enclosures (e.g. of large electric machines)  Excluded  Excluded  Excluded  6.5  6.5  Gasket retention  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  6.6  6.6  Electromagnetic and ultrasonic energy radiating equipment  –  6.6.1  General  Applies  Applies  Excluded  6.6.1  6.6.2  Radio frequency sources  Applies  Applies  Excluded  6.6.3  6.6.3  Ultrasonic sources  Applies  Applies  Excluded  6.6.2  6.6.4  Lasers, luminaires and other non-divergent continuous wave optical sources  Modified  Modified  Excluded  7  7  Non-metallic enclosures and non-metallic parts of enclosures  7.1  7.1  General  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  7.2  7.2  Thermal endurance  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  7.3  7.3  Resistance to ultraviolet light  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  7.4  7.4  Electrostatic charges on external non-metallic materials  Applies  Applies  Excluded  7.5  7.5  Attached external conductive parts  Applies  Applies  Excluded  8  8  Metallic enclosures and metallic parts of enclosures  Applies  Applies  Excluded  9  9  Fasteners  Excluded  Excluded  Excluded  10  10  Interlocking devices  Applies  Applies  Excluded  11  11  Bushings  Excluded  Excluded  Excluded  12  –  Materials used for cementing  Excluded except when 1 is applied  Excluded except when 1 are applied  Excluded except when 1 is applied  –  12  (Reserved for future use)  –  –  –  13  13  Ex Components  Applies  Applies  Applies  14  14  Connection facilities  14.1  14.1  General  Applies  Applies  Applies  14.2  –  Termination compartment  Applies  Applies  Applies  14.3  14.2  Type of Protection  Applies  Applies  Modified  14.4  14.3  Creepage and clearance  Applies  Applies  Applies  15  15  Connection facilities for earthing or bonding conductors  Excluded  Excluded  Excluded  16  16  Entries into enclosures  16.1  16.1  General  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  16.2  16.2  Identification of entries  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  16.3  16.3  Cable Glands  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  16.4  16.4  Blanking elements  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  16.5  16.5  Thread adapters  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  16.6  16.6  Temperature at branching point and entry point  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  16.7  16.7  Electrostatic charges of cable sheaths  Applies  Applies  Applies  17  17  Supplementary requirements for electric machines  Excluded  Excluded  Excluded  18  18  Supplementary requirements for switchgear  Excluded  Excluded  Excluded  19  –  Supplementary requirements for fuses  Excluded  Excluded  Excluded  –  19  Reserved for future use  –  –  –  20  20  Supplementary requirements for external plugs, socket outlets and connectors for field wiring connection  Excluded  Excluded  Excluded  21  21  Supplementary requirements for luminaires  Excluded  Excluded  Excluded  22  22  Supplementary requirements for caplights and handlights  22.1  22.1  Group I caplights  Applies  Excluded  Excluded  22.2  22.2  Group II and Group III caplights and handlights  Excluded  Excluded  Excluded  23  23  Equipment incorporating cells and batteries  23.1  23.1  General  Applies  Applies  Applies  23.2  23.2  Interconnection of cells to form batteries  Excluded  Excluded  Excluded  23.3  23.3  Cell types  Modified  Modified  Modified  23.4  23.4  Cells in a battery  Applies  Applies  Applies  23.5  23.5  Ratings of batteries  Applies  Applies  Applies  23.6  23.6  Interchangeability  Applies  Applies  Applies  23.7  23.7  Charging of primary batteries  Applies  Applies  Applies  23.8  23.8  Leakage  Applies  Applies  Applies  23.9  23.9  Connections  Applies  Applies  Applies  23.10  23.10  Orientation  Applies  Applies  Applies  23.11  23.11  Replacement of cells or batteries  Applies  Applies  Applies  23.12  23.12  Replaceable battery pack  Applies  Applies  Applies  24  24  Documentation  Applies  Applies  Applies  25  25  Compliance of prototype or sample with documents  Applies  Applies  Applies  26  26  Type tests  26.1  26.1  General  Applies  Applies  Applies  26.2  26.2  Test configuration  Applies  Applies  Applies  26.3  26.3  Tests in explosive test mixtures  Applies  Applies  Applies  26.4  26.4  Tests of enclosures  26.4.1  26.4.1  Order of tests  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  26.4.2  26.4.2  Resistance to impact  Excluded except see a  Excluded except see a  Excluded except see a  26.4.3  26.4.3  Drop test  Applies  Applies  Applies  26.4.4  26.4.4  Acceptance criteria  Applies  Applies  Applies  26.4.5  26.4.5  Degree of protection (IP) by enclosures  Applies  Applies  Applies  26.5  26.5  Thermal tests  26.5.1  26.5.1  Temperature measurement  26.5.1.1  26.5.1.1  General  Applies  Applies  Excluded  26.5.1.2  26.5.1.2  Service temperature  Applies  Applies  Applies  26.5.1.3  26.5.1.3  Maximum surface temperature  Modified  Modified  Excluded  26.5.2  26.5.2  Thermal shock test  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  26.5.3  26.5.3  Small component ignition test (Group I and Group II)  Applies  Excluded  Excluded  26.6  26.6  Torque test for bushings  Excluded  Excluded  Excluded  26.7  26.7  Non-metallic enclosures or non-metallic parts of enclosures  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  26.8  26.8  Thermal endurance to heat  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  26.9  26.9  Thermal endurance to cold  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  26.10  26.10  Resistance to UV light  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  26.11  26.11  Resistance to chemical agents for Group I equipment  Excluded except when 1 is applied  Excluded  Excluded  26.12  26.12  Earth continuity  Excluded  Excluded  Excluded  26.13  26.13  Surface resistance test of parts of enclosures of non-metallic materials  Applies  Applies  Excluded  26.14  26.14  Measurement of capacitance  Applies  Applies  Excluded  26.15  26.15  Verification of ratings of ventilating fans  Excluded  Excluded  Excluded  26.16  26.16  Alternative qualification of elastomeric sealing O-rings  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  NR  26.17  Transferred charge test  Applies  Excluded  Excluded  27  27  Routine tests  Applies  Applies  Applies  28  28  Manufacturer's responsibility  Applies b  Applies b  Applies  29  29  Marking  29.1  29.1  Applicability  Applies  Applies  Applies  29.2  29.2  Location  Applies  Applies  Applies  29.3  29.3  General  Applies  Applies  Applies  29.4  29.4  Ex marking for explosive gas atmospheres  Applies  Excluded  Applies  29.5  29.5  Ex marking for explosive dust atmospheres  Excluded  Applies  Applies  29.6  29.6  Combined types (or levels) of protection  Applies  Applies  Applies  29.7  29.7  Multiple types of protection  Applies  Applies  Applies  29.8  29.8  Ga equipment using two independent Gb types (or levels) of protection  Applies  Excluded  Excluded  NR  29.9  Boundary wall  Applies  Applies  Excluded  29.9  29.10  Ex Components  Applies  Applies  Applies  29.10  29.11  Small Ex Equipment and small Ex Components  Applies  Applies  Applies  29.11  29.12  Extremely small equipment and extremely small Ex Components  Applies  Applies  Applies  29.12  29.13  Warning markings  Applies  Applies  Applies  29.13  –  Alternate marking of Equipment Protection Levels (EPLs)  Applies  Applies  Applies  29.13.1  –  Alternate marking of Type of Protection for explosive gas atmospheres  Applies  Excluded  Applies  29.13.2  –  Alternate marking of Type of Protection for explosive dust atmospheres  Excluded  Applies  Applies  29.14  29.14  Cells and batteries  Applies  Applies  Applies  29.15  29.15  Electrical machines operated with a converter  Excluded  Excluded  Excluded  29.16  29.16  Examples of marking  Examples only  Examples only  Examples only  30  30  Instructions  30.1  30.1  General  Applies  Applies  Applies  30.2  30.2  Cells and batteries  Applies  Applies  Applies  30.3  30.3  Electric machines  Excluded  Excluded  Excluded  30.4  30.4  Ventilating fans  Excluded  Excluded  Excluded  –  30.5  Cable Glands  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  Annex A  Annex A  Supplementary requirements for cable glands  Excluded except when 1 is applied  Excluded except when 1 is applied  Excluded except when 1 is applied  Annex B  Annex B  Requirements for Ex Components  Applies  Applies  Applies  Annex C  Annex C  Example of rig for resistance to impact test  Informative Annex  Informative Annex  Informative Annex  Annex D  Annex D  Electric machines connected to converters  Informative Annex  Informative Annex  Informative Annex  Annex E  Annex E  Temperature evaluation of electric machines  Informative Annex  Informative Annex  Informative Annex  Annex F  Annex F  Guideline flowchart for tests of non-metallic enclosures  Informative Annex  Informative Annex  Informative Annex  or non-metallic parts of enclosures (26.4)  –  Annex G  Guidance flowchart for tests of cable glands  Informative Annex  Informative Annex  Informative Annex  –  Annex H  Shaft voltages resulting in motor bearing or shaft brush sparking. Discharge energy calculation  Informative Annex  Informative Annex  Informative Annex  Applies – This Clause / Subclause of IEC 60079-0 is applied without change.  Excluded – This Clause / Subclause of IEC 60079-0 does not apply.  Modified – This Clause / Subclause of IEC 60079-0 is modified as detailed in this document.  NOTE 1 The applicable Clauses / Subclauses of IEC 60079-0 are identified by the Clause / Subclause title which is normative. This document was written against the specific requirements of IEC 60079-0:2017 (Ed.7). The Clause / Subclause numbers for the 7th and previous edition are shown for information only. This is to enable the general requirements of IEC 60079-0:2011 (Ed.6) to be used where necessary with this part of IEC 60079. Where there were no requirements in the 6th edition but there are for the 7th edition (indicated by NR against the 6th edition only), or where there is a conflict between requirements, the later edition requirements take precedence.  NOTE 2 A shaded row in the above table indicates that this is a Clause heading. In cases where the applicability is the same for all the subclauses the 'Applies' or 'Excluded' is listed in the heading row and the subclauses are not expanded. Where the application of the individual sub-clauses may be different, these are expanded in the above table and the applicability for each is listed.  a Excluded except when 1 is applied, or as required by 1 or 11.  b Excluded for simple apparatus. See 5 and 5.  “IEC 60079-0” to “UL 60079-0 and CSA C22.2 No. 60079-0”  “IEC 60079-11 to “UL 60079-11 and CSA C22.2 No. 60079-11”