AS NZS IEC 60079.25-2022 (2025) PDF

Full title and description

AS/NZS IEC 60079.25:2022 — Explosive atmospheres — Part 25: Intrinsically safe electrical systems. This joint Australian/New Zealand adoption identically adopts IEC 60079-25 (third edition, 2020) and contains specific requirements for the design, construction and assessment of intrinsically safe (Type of Protection “i”) systems intended for use, wholly or in part, in locations requiring Group I, II or III Ex equipment. Amendment No. 1 (March 14, 2025) has been issued to update front matter and corrigenda where applicable.

Abstract

This standard provides detailed technical requirements, definitions and assessment rules for intrinsically safe electrical systems, including limits on energy, requirements for interconnections, cable parameters (capacitance, inductance), documentation (descriptive system document), and testing/inspection guidance. It is intended for use by system designers, manufacturers, specialist consultants and competent end‑user staff responsible for specifying or assessing intrinsically safe systems in hazardous (explosive atmosphere) locations.

General information

• Status: Current (AS/NZS adoption published and maintained; amendment Amd 1:2025 issued).
• Publication date: AS/NZS IEC 60079.25:2022 — 11 February 2022; Amendment No. 1 published 14 March 2025.
• Publisher: Standards Australia / Standards New Zealand (joint AS/NZS adoption).
• ICS / categories: 29.260.20 — Electrical apparatus for explosive atmospheres (Explosion protection / hazardous area electrical equipment).
• Edition / version: AS/NZS IEC 60079.25:2022 (adopts IEC 60079-25:2020, 3rd edition); includes Amendment No. 1 (2025).
• Number of pages: Main publication 49 pages; Amendment Amd 1:2025 — 3 pages.

Scope

This part of IEC/AS/NZS 60079 specifies the specific requirements for intrinsically safe electrical systems (Type of Protection “i”). It covers requirements for the design, construction, evaluation and documentation of intrinsically safe circuits and systems that may be used, in whole or in part, in hazardous locations where Group I (mining), Group II (gases/vapours) or Group III (dust) equipment is required. The standard supplements and modifies the general requirements of AS/NZS IEC 60079-0 and the intrinsic safety equipment standard AS/NZS 60079.11; installation interfaces are addressed by IEC/AS/NZS 60079-14.

Key topics and requirements

• Definitions and terminology for intrinsically safe circuits and components (intrinsically safe circuits, multi‑circuit cables, cable parameters).
• Limits on energy, voltage, current and temperature to prevent ignition (energy‑limiting circuit design).
• Requirements for interconnection, total cable capacitance and inductance, and cable inductance/resistance ratio (Lc/Rc).
• Descriptive system documentation — mandatory documentation listing components, parameters and wiring needed for safe assessment and maintenance.
• Assessment, testing and verification procedures for intrinsically safe apparatus and systems (including inspection and conformity checks).
• Guidance on selecting protective barriers, isolators and other components used to achieve intrinsic safety.
• Marking, user information and installation/maintenance notes where relevant; relationship to other IEC/AS/NZS 60079 parts.
• Corrections and editorial changes applied via corrigenda and Amendment 1 (2025) to keep the joint adoption aligned with IEC changes.

Typical use and users

Primary users are electrical and instrumentation designers, manufacturers of intrinsically safe equipment, compliance/approval engineers, hazardous area consultants, facilities engineers in mining, oil & gas, chemical and processing industries, and maintenance staff responsible for safety documentation and modifications. The standard is used to design safe intrinsically safe circuits, compile descriptive system documents, carry out conformity assessments, and prepare installation and maintenance procedures for hazardous areas.

Related standards

AS/NZS IEC 60079.25 is intended to be used alongside: AS/NZS IEC 60079-0 (general requirements for equipment in explosive atmospheres), AS/NZS 60079.11 (intrinsic safety “i” — equipment requirements), AS/NZS 60079-14 (installation), and other parts of the IEC 60079 series covering different types of protection and application‑specific requirements. National adoptions and corrigenda (including the 2025 amendment) align AS/NZS text with IEC revisions.

Keywords

intrinsic safety, intrinsically safe systems, explosive atmospheres, hazardous areas, IEC 60079-25, AS/NZS, energy limiting, descriptive system document, cable capacitance, cable inductance, Ex equipment, Type i protection.

FAQ

Q: What is this standard?

A: AS/NZS IEC 60079.25:2022 is the joint Australian/New Zealand adoption of IEC 60079-25 (third edition, 2020) that sets requirements for intrinsically safe electrical systems (Type of Protection “i”). An Amendment No. 1 was published 14 March 2025.

Q: What does it cover?

A: It covers design, construction, assessment and documentation rules for intrinsically safe circuits and systems including limits on energy, cable parameters (capacitance/inductance), interconnection rules, required documentation (descriptive system document), testing and verification, and marking/user information. It supplements AS/NZS IEC 60079-0 and AS/NZS 60079.11.

Q: Who typically uses it?

A: System designers, equipment manufacturers, certification and compliance engineers, consultants and end‑user technical staff in industries with explosive atmospheres (mining, oil & gas, chemical, grain/dust handling, process plants).

Q: Is it current or superseded?

A: The AS/NZS IEC 60079.25:2022 adoption is current. It adopts IEC 60079-25:2020 and has been maintained with corrigenda and Amendment No. 1 published 14 March 2025. Previous national editions (for example AS/NZS 60079.25:2011) are superseded.

Q: Is it part of a series?

A: Yes — it is one part of the IEC/AS/NZS 60079 series on explosive atmospheres; other relevant parts include 60079-0 (general requirements), 60079-11 (intrinsic safety equipment), 60079-14 (installation), 60079-31 (dust, protection by enclosure) and additional parts addressing other protection types and guidance.

Q: What are the key keywords?

A: Intrinsic safety, Type i, explosive atmospheres, Ex, intrinsically safe circuits, descriptive system document, cable capacitance/inductance, energy limiting, hazardous area.