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CAN/CSA-C22.2 No. 60079-25-14 (2018): Intrinsically Safe Electrical Systems – Scope, Technical Requirements, and Compliance Guide
A comprehensive overview of the Canadian standard for the design, assessment, and installation of intrinsically safe electrical systems in explosive atmospheres
1. Scope and General Application
CAN/CSA C22.2 No. 60079-25-14 (2018) is the Canadian national adoption of IEC 60079-25:2010, with Canadian modifications, forming part of the Canadian Electrical Code Part II (C22.2 series). This standard specifies requirements for the design, construction, and assessment of intrinsically safe electrical systems intended for use in explosive gas atmospheres. It covers systems that are either fully certified as a unit (system certification) or assembled from separately certified apparatus using the entity concept or a combination approach.
Tip: The standard applies to systems where the maximum surface temperature and the maximum voltage, current, and power are limited to levels that prevent ignition of a surrounding explosive atmosphere under normal and fault conditions.
The scope includes systems operating in areas classified as Zone 0, Zone 1, or Zone 2 according to the Canadian Electrical Code Part I (CSA C22.1) and IEC classification methods. It is essential for engineers, installers, and inspectors dealing with instrumentation, measurement, and control circuits in potentially flammable environments.
1.1 Relationship with Other Standards
This standard is part of a series of explosive atmosphere standards adopted by CSA Group. It complements CAN/CSA-C22.2 No. 60079-11 (intrinsic safety apparatus) and CAN/CSA-C22.2 No. 60079-14 (electrical installations in hazardous areas). It also aligns with the entity parameter approach used in ISA RP12.6 and other international intrinsic safety practices.
2. Technical Requirements and System Integrity
The central requirement of CAN/CSA C22.2 No. 60079-25-14 (2018) is that the intrinsically safe system must be capable of safe operation in its intended explosive atmosphere. The standard defines two primary methods for achieving and verifying intrinsic safety:
| Assessment Method | Description | Key Parameters |
|---|---|---|
| System Certification | The entire system (e.g., barrier, cable, field device) is assessed as a unit for a defined grouping. | Maximum voltage (Ui), current (Ii), power (Pi), capacitance (Ci), inductance (Li). |
| Entity Concept | Separately certified apparatus are interconnected using entity parameters that ensure the combination remains intrinsically safe. | Maximum voltage (Uo), current (Io), power (Po), permitted capacitance (Co), permitted inductance (Lo). |
Users must demonstrate that for every interconnection of apparatus (including cables), the entity parameters of the source device do not exceed the input ratings of the receiving device. In addition, the cable capacitance and inductance must be subtracted from the permitted values.
2.1 System Documentation and Marking
The standard requires a System Description Document that includes:
- List of all system components with their certification numbers and entity parameters.
- Cable specifications (capacitance, inductance, resistance per unit length).
- Maximum ambient temperature range and temperature classification (T-rating).
- Proof of intrinsic safety, including calculations or justification for each interconnection.
Warning: Incomplete documentation is a common non-compliance issue. The System Description Document must be maintained and available for inspection; changes to any component require re-verification of the entire system.
2.2 Special Conditions and Fault Assessment
The standard also addresses multiple faults and the possibility of galvanic isolation. For systems with more than one fault, the designer must assess the probability of simultaneous faults and the resulting ignition risk. When barriers or isolators provide galvanic isolation, the separation requirements of IEC 60079-11 apply.
Key Benefit: The entity concept allows flexibility in system design and maintenance. Components from different manufacturers can be mixed, provided the entity parameter limits are respected, reducing supply chain constraints.
3. Implementation Highlights and Assessment Methods
Implementation of CAN/CSA C22.2 No. 60079-25-14 (2018) typically follows a stepwise process:
- System definition: Identify all components (sensors, actuators, barriers, cables) and their certified characteristics.
- Interconnection assessment: Compare entity parameters and ensure that Uo ≤ Ui, Io ≤ Ii, Po ≤ Pi, and that cable parameters (Ccable, Lcable) fall within the allowed limits.
- Temperature classification: Verify that the system’s maximum surface temperature (under fault conditions) does not exceed the allowed T-rating for the area classification.
- Documentation: Prepare the System Description Document and affix the system label or marking to the enclosure.
The standard also recommends periodic inspection and maintenance in accordance with CAN/CSA C22.1 and the manufacturer’s instructions. Any modification to the system invalidates the Intrinsic Safety assessment and requires re-certification.
3.1 Example Parameter Comparison Table (Entity Concept)
| Component | Certification | Entity Parameter Output | Input Limits |
|---|---|---|---|
| Isolator Barrier | CSA 60079-11 | Uo = 28 V, Io = 93 mA, Po = 1.2 W | – |
| Temperature Transmitter | CSA 60079-11 | – | Ui = 30 V, Ii = 100 mA, Pi = 1.5 W |
| Cable (100 m, 0.5 mm²) | Specified | Ccable = 10 nF, Lcable = 0.5 mH | Permitted Co = 200 nF, Lo = 5 mH |
In this example, the barrier output parameters are within the transmitter input limits, and the cable parameters are well below the permitted values, confirming intrinsic safety.
4. Compliance and Certification Notes
Compliance with CAN/CSA C22.2 No. 60079-25-14 (2018) is mandatory in Canada for intrinsically safe systems installed in explosive atmospheres. The standard is recognized by provincial regulatory authorities, and equipment must be certified by an accredited certification body (e.g., CSA Group, UL, Intertek).
Critical Note: The entity concept does not permit mixing components that are not individually certified to a recognized intrinsic safety standard. All apparatus must display an accepted certification mark (e.g., CSA, FM, ATEX, IECEx) and list entity parameters or be covered by the system certificate.
System certification is typically performed by the system integrator or the end user. The burden of proof rests on the owner/operator to demonstrate that the assembled system meets the requirements. Certification bodies offer system assessment services, and some manufacturers provide pre-engineered system solutions that carry system certificates.
Audit and inspection bodies focus on:
- Availability and completeness of the System Description Document.
- Correct marking of system boundaries and all components.
- Proper installation per the manufacturer’s instructions and the Canadian Electrical Code Part I.
- Training of personnel responsible for design, installation, and maintenance.
Tip: To simplify compliance, consider using pre-certified intrinsically safe system kits from manufacturers. These come with complete documentation and reduce the risk of parameter mismatches.
Frequently Asked Questions
Q: What is the difference between system certification and the entity concept in CAN/CSA C22.2 No. 60079-25-14?
A: System certification treats the whole system as a certified unit, with a single certificate covering a defined combination of components. The entity concept allows users to interconnect any certified apparatus as long as entity parameters (Uo, Io, Po, Co, Lo) are not exceeded by the source and cable contributions. Both methods are permitted, but the entity concept offers greater flexibility in maintenance and in replacing components with equivalent certified parts.
A: System certification treats the whole system as a certified unit, with a single certificate covering a defined combination of components. The entity concept allows users to interconnect any certified apparatus as long as entity parameters (Uo, Io, Po, Co, Lo) are not exceeded by the source and cable contributions. Both methods are permitted, but the entity concept offers greater flexibility in maintenance and in replacing components with equivalent certified parts.
Q: How does the standard address cable capacitance and inductance?
A: The standard requires that the total capacitance and inductance of the cable between source and load be added to the source’s permitted values (Co, Lo). The sum must not exceed the receiving device’s input capacitance (Ci) and inductance (Li). If the cable characteristics are unknown, default conservative values from the standard may be used.
A: The standard requires that the total capacitance and inductance of the cable between source and load be added to the source’s permitted values (Co, Lo). The sum must not exceed the receiving device’s input capacitance (Ci) and inductance (Li). If the cable characteristics are unknown, default conservative values from the standard may be used.
Q: What documentation is required for compliance?
A: The mandatory document is the System Description Document, which contains a full list of components, their certification details, entity parameters, cable data, temperature classification, and interconnection calculations. This document must be made available to the authority having jurisdiction upon request.
A: The mandatory document is the System Description Document, which contains a full list of components, their certification details, entity parameters, cable data, temperature classification, and interconnection calculations. This document must be made available to the authority having jurisdiction upon request.
Q: Can this standard be used for systems in dust atmospheres?
A: CAN/CSA C22.2 No. 60079-25-14 (2018) specifically addresses explosive gas atmospheres (Group II). For dust atmospheres (Group III), the user should refer to the related Canadian standard CAN/CSA C22.2 No. 60079-25-14 is not applicable; instead, the equivalent standard for dust is CAN/CSA-C22.2 No. 60079-25 does not exist in dust versions. For intrinsically safe dust systems, refer to CAN/CSA C22.2 No. 60079-11 together with dust-specific installation standards.
A: CAN/CSA C22.2 No. 60079-25-14 (2018) specifically addresses explosive gas atmospheres (Group II). For dust atmospheres (Group III), the user should refer to the related Canadian standard CAN/CSA C22.2 No. 60079-25-14 is not applicable; instead, the equivalent standard for dust is CAN/CSA-C22.2 No. 60079-25 does not exist in dust versions. For intrinsically safe dust systems, refer to CAN/CSA C22.2 No. 60079-11 together with dust-specific installation standards.
Article prepared in 2026 based on CAN/CSA C22.2 No. 60079-25-14 (2018). Always refer to the latest edition and applicable local regulations for full compliance.