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CAN CSA C22.2 No. 60079-18-16: Standard for Equipment Protection by Encapsulation “m” for Explosive Atmospheres
Comprehensive Guide to Encapsulation Protection Type ‘m’ for Hazardous Locations in Canada
Scope and Application
CAN CSA C22.2 No. 60079-18-16 is the Canadian adoption of IEC 60079-18, specifying requirements for the design, construction, testing, and marking of electrical equipment protected by encapsulation type “m” intended for use in explosive gas atmospheres. This standard is part of the Canadian Electrical Code, Part II (C22.2 series) and harmonizes national requirements with international practice while addressing specific regulatory and climatic conditions in Canada.
The standard applies to equipment that limits the energy of sparks or thermal effects capable of igniting a surrounding explosive atmosphere by completely encapsulating components that may ignite a mixture. Encapsulation type “m” may be used for equipment in Zones 0, 1, and 2 for gas groups IIA, IIB, and IIC, depending on the level of protection (mb, mc) and associated performance requirements.
Tip: CAN CSA C22.2 No. 60079-18-16 supersedes earlier editions and aligns with the IEC 60079-18:2014, edition 3.0. Always verify the current year of the adopted edition in the Canadian register of standards.
Technical Requirements
Encapsulation Material and Process
The encapsulation compound must provide electrical insulation, mechanical strength, thermal conductivity, and corrosion resistance. It must also maintain its integrity under normal service conditions, foreseeable malfunctions, and environmental stresses including temperature, humidity, and chemical exposure.
- Dielectric strength and leakage current limits are verified by routine and type tests.
- Maximum encapsulation thickness must not exceed values specified in the standard to avoid excessive thermal resistance.
- Curing and processing conditions are controlled to prevent voids, cracks, or delamination.
Temperature Classification
The maximum surface temperature of the encapsulation under normal and fault conditions must not exceed the temperature class of the equipment for the intended gas group. The standard specifies test conditions to determine the temperature class (T1–T6) and the maximum ambient temperature.
| Temperature Class | Maximum Surface Temperature (°C) | Typical Gas Groups | Permitted Zones (Type “mc”) |
|---|---|---|---|
| T1 | 450 | IIA, IIB, IIC | 1, 2 |
| T2 | 300 | IIA, IIB, IIC | 1, 2 |
| T3 | 200 | IIA, IIB | 1, 2 |
| T4 | 135 | IIA, IIB | 1, 2 |
| T5 | 100 | IIA | 1, 2 |
| T6 | 85 | IIA | 1, 2 |
Warning: Equipment marked with temperature class T6 may only be used in gas group IIA unless certified by additional tests for hydrogen and acetylene. Verify the Ex marking label for all limitations.
Levels of Protection
The standard defines two levels of protection:
- Type “mb” – High protection level: permits use in Zone 1 (and by extension Zone 2). The encapsulation must withstand any single fault condition without causing ignition.
- Type “mc” – Enhanced protection level: permits use in Zone 2 only. The encapsulation must withstand normal operation and foreseeable rare faults.
For Zone 0, only type “ma” (per IEC 60079-18) is recognized, but CAN CSA C22.2 No. 60079-18-16 only covers mb and mc. Equipment for Zone 0 must reference the IEC edition or use another protection concept (intrinsic safety).
Testing Requirements
CAN CSA C22.2 No. 60079-18-16 requires both type tests and routine tests:
- Type tests: impulse voltage test, dielectric strength test, leakage current measurement, thermal endurance cycling, impact test, and ingress protection verification (minimum IP54 for gas groups).
- Routine tests: dielectric strength test on each unit, measurement of leakage current or insulation resistance.
The test sequences and acceptance criteria are detailed in the standard’s normative annexes.
Implementation Highlights
Design Considerations
Encapsulation designers must pay special attention to:
- Component placement to avoid touching the encapsulation surface (minimum creepage and clearance distances).
- Heat dissipation: power components may need embedded heat sinks or thermally conductive fillers.
- Expansion and contraction: the compound must accommodate thermal expansion without cracking or delamination from lead wires or the housing.
PET (Polyethylene terephthalate) tapes, sleeves, and filler materials must be compatible with the potting compound and the operating temperature range.
Good Practice: Use computer modeling (FEA) for thermal and stress analysis early in the design phase to reduce the risk of failure during type testing. Many Canadian certifiers accept simulation results as supporting documentation.
Marking and Documentation
The marking of encapsulated equipment must include:
- the protection symbol Ex mb or Ex mc
- the temperature class and maximum ambient temperature (e.g., –20 °C ≤ Ta ≤ +40 °C)
- the gas group(s) and zones for which the equipment is certified
- the certification body mark (e.g., CSA, UL) and certificate number
All documentation must be prepared in English and French for the Canadian market. The manufacturer’s Declaration of Conformity must reference CAN CSA C22.2 No. 60079-18-16.
Critical: Equipment bearing only the IEC 60079-18 marking without the Canadian national deviation (CAN CSA C22.2 No. 60079-18-16) is not accepted by Canadian authorities for installation in hazardous locations. Obtain a national certification from an accredited body.
Compliance Notes
Regulatory Framework
CAN CSA C22.2 No. 60079-18-16 is recognized as an alternative standard for the installation codes of the Canadian Electrical Code, Part I (CSA C22.1). Equipment complying with this standard may be used in hazardous locations where the electrical inspection authority accepts Part II standards. The standard also references IEC 60079-0 (General Requirements) and IEC 60079-11 (Intrinsic Safety) for combined protection.
Certification Process
Manufacturers must submit samples to a recognized certification body (e.g., CSA Group, UL Canada, Intertek) for type testing. The certification body reviews the design documentation, performs or witnesses the required tests, and issues a certificate of compliance. The certification is typically valid for five years with periodic factory inspections.
Maintenance and Repairs
Encapsulated equipment is considered non‑repairable. If the encapsulation is damaged, the entire unit must be replaced. Field modifications are not permitted. Users must follow the manufacturer’s instructions for storage, installation, and cleaning to avoid damaging the encapsulation.
Tip: For repair shops, CNC machining may be used to expose a component, but re‑encapsulation using an approved compound and process must be performed under the supervision of the original manufacturer or a certified repair facility. Always obtain approval from the responsible certification body before attempting a repair.
End‑users should maintain records of the certification number and ambient temperature limits for each unit, as the temperature class can be de‑rated if the encapsulation surface is covered with insulating dust or debris.
Frequently Asked Questions
Q: Can CAN CSA C22.2 No. 60079-18-16 be used for equipment intended for Zone 0?
A: No. This Canadian standard only covers protection types “mb” (Zone 1) and “mc” (Zone 2). For Zone 0, only “ma” according to IEC 60079-18 is recognized, and such equipment must meet additional requirements or be protected by another method such as intrinsic safety (Ex ia).
A: No. This Canadian standard only covers protection types “mb” (Zone 1) and “mc” (Zone 2). For Zone 0, only “ma” according to IEC 60079-18 is recognized, and such equipment must meet additional requirements or be protected by another method such as intrinsic safety (Ex ia).
Q: What are the differences between the IEC 60079-18 and the Canadian adoption?
A: CAN CSA C22.2 No. 60079-18-16 includes Canadian deviations covering national electrical code references, bilingual marking requirements (English and French), and specific climatic test conditions (e.g., cold test at –40 °C for some regions). The technical content is otherwise largely identical to IEC 60079-18:2014.
A: CAN CSA C22.2 No. 60079-18-16 includes Canadian deviations covering national electrical code references, bilingual marking requirements (English and French), and specific climatic test conditions (e.g., cold test at –40 °C for some regions). The technical content is otherwise largely identical to IEC 60079-18:2014.
Q: Is it allowed to repair an encapsulated device by re‑potting?
A: Generally not. The encapsulation process is certified as a whole, including the compound, curing cycle, and quality control. Field re‑potting void the certification. Only the original manufacturer or an authorized repair facility that uses the exact same approved compound and process may perform repairs, and each repaired unit must be re‑tested per the routine test requirements.
A: Generally not. The encapsulation process is certified as a whole, including the compound, curing cycle, and quality control. Field re‑potting void the certification. Only the original manufacturer or an authorized repair facility that uses the exact same approved compound and process may perform repairs, and each repaired unit must be re‑tested per the routine test requirements.
Q: Does the standard require IP (ingress protection) rating for encapsulated enclosures?
A: Yes. For gas groups IIA and IIB, an IP54 enclosure is required as a minimum (except when the encapsulation itself is the only enclosure, which may have no additional housing). For gas group IIC, IP6X is required. The ingress protection test must be conducted in accordance with IEC 60079-0.
A: Yes. For gas groups IIA and IIB, an IP54 enclosure is required as a minimum (except when the encapsulation itself is the only enclosure, which may have no additional housing). For gas group IIC, IP6X is required. The ingress protection test must be conducted in accordance with IEC 60079-0.
© 2026 Canadian Standards for Hazardous Locations. This article is for informational purposes and does not replace the official standard. Always refer to the latest edition of CAN CSA C22.2 No. 60079-18-16.