IEC 60079-11:2023

Overview

IEC 60079-11:2023 - "Explosive atmospheres - Part 11: Equipment protection by intrinsic safety 'i'" - is the international standard that specifies construction, testing and assessment requirements for intrinsically safe apparatus and associated equipment intended for use in explosive atmospheres. The standard covers electrical circuits that are designed so they are incapable of causing ignition of surrounding flammable gas, vapour or dust atmospheres, including circuits that are intrinsically safe only under defined conditions (for example battery-supplied only). This 2023 edition incorporates Corrigendum 1 and multiple interpretation sheets (2024–2025).

Key topics and requirements

The standard details technical requirements and test methods needed to achieve intrinsic safety ("i"). Major topics include:

• Levels of protection: criteria for protection levels ia, ib, ic and their assessment conditions.
• Ignition compliance: spark and thermal ignition testing, safety factors, and special rules for circuits with or without semiconductor limitations.
• Apparatus construction: enclosure requirements, terminals, earth connections, connectors and wiring practices.
• Separation and insulation: required separations, types of separation, printed circuit board (PCB) considerations and failure modes.
• Component characteristics and failures: ratings and failure behavior for resistors, capacitors, inductors, semiconductors, transformers, relays, fuses, batteries and other components on which intrinsic safety depends.
• Battery & cell requirements: construction, venting, replacement and charging considerations for batteries used in hazardous areas.
• Encapsulation, coatings and mechanical protection: when and how to use encapsulation or barriers to maintain intrinsic safety.
• Type tests & verification: spark ignition tests, thermal tests and type examination procedures for certification.
• Special apparatus topics: diode safety barriers, FISCO apparatus, signal isolators and other supplementary requirements.

Applications and users

IEC 60079-11 is essential for anyone designing, manufacturing, certifying or installing electrical equipment that will operate in potentially explosive atmospheres, including:

• Manufacturers of sensors, transmitters, handheld devices, control electronics and intrinsically safe barriers
• Design and safety engineers in oil & gas, petrochemical, mining, pharmaceuticals, food processing, and grain-handling industries
• Certification bodies and testing laboratories performing type examinations and compliance testing
• Installation and maintenance personnel responsible for equipment selection, wiring and safe replacement of batteries or modules

Related standards

• IEC 60079-0 (general requirements for explosive atmospheres) - referenced for other Types of Protection and general rules.
• Other IEC 60079 series documents cover specific protection methods (e.g., flameproof "d", increased safety "e") and subsystem requirements.

Keywords: IEC 60079-11, intrinsic safety, intrinsically safe apparatus, explosive atmospheres, equipment protection "i", intrinsically safe circuits, hazardous area equipment.