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CAN CSA C22.2 No. 60079-5-16: Equipment Protection by Powder Filling (Type “q”) for Explosive Atmospheres
Canadian National Standard for Electrical Equipment in Hazardous Locations Adopting IEC 60079-5:2015 with National Deviations
1. Scope and Application
CAN CSA C22.2 No. 60079-5-16 is the Canadian national adoption of the international standard IEC 60079-5:2015 (Ed. 3), part of the IEC 60079 series for electrical equipment in explosive gas atmospheres. It specifically addresses the type of protection “q” — equipment protection by powder filling. This technique involves completely filling an enclosure with a fine, solid powder (typically quartz or glass microspheres) to prevent the ignition of an external explosive atmosphere. The standard sets the requirements for design, construction, testing, and marking of powder-filled electrical equipment intended for use in Zone 1 (and in some cases Zone 2) hazardous areas where explosive gas mixtures can occur.
This standard is part of the C22.2 family of CSA Group electrical standards, which harmonize with the Canadian Electrical Code (CE Code) for installations in hazardous locations. It applies to equipment with a rated voltage not exceeding 10 kV (r.m.s.) and may be used for Equipment Protection Level (EPL) Gb or Gc depending on the construction and testing.
Tip: While IEC 60079-5 applies globally, the Canadian adoption may include national deviations that reflect local regulatory requirements and climatic conditions. Always refer to the latest edition of CAN CSA C22.2 No. 60079-5-16 for official compliance.
2. Technical Requirements for Powder-Filled Enclosures
CAN CSA C22.2 No. 60079-5-16 defines several critical parameters for powder filling, including the nature of the filling material, enclosure design, and temperature limits. The powder must be non‑flammable, electrically insulating, and of a defined grain size distribution. Typical materials are feldspar, silica sand, or glass beads with a grain size between 0.1 mm and 1.0 mm. The filling must be compacted so that voids are minimized, preventing any internal arcing or heated particles from escaping.
| Parameter | Requirement | Test / Verification |
|---|---|---|
| Maximum filling granule size | ≤ 1.0 mm (99% passing) | Sieve analysis per ISO 3310‑1 |
| Minimum granule size | ≥ 0.1 mm (to avoid dust hazards) | Sieve analysis |
| Filling density (compacted) | ≥ 1.2 g/cm³ (typical) | Mass/volume measurement |
| Maximum clearance to enclosure wall | Depending on ignition energy (≥ 5 mm for ≤ 10 J) | By construction |
| Maximum surface temperature | Temperature class of equipment (T6 to T1) | Thermal tests with rated current + 10 K margin |
| Electrical creepage distances | Per Table 2 of the standard (pollution degree 3) | Measured in clean condition |
| IP degree of enclosure | Minimum IP54 (IP6X for dust, IPX5 for water) | Per IEC 60529 |
The standard also specifies that the free space above and between internal components must be completely filled with powder so that no cavities remain. Thermal testing under worst‑case overload conditions must be performed to verify that the external surface temperature does not exceed the marked temperature class. In addition, all external conductive parts must be bonded to a protective earth terminal, and any openings must be sealed to prevent powder leakage.
Warning: Internal wiring must be firmly secured to prevent movement that could create voids in the powder. Any settling of the fill during transport or operation can compromise the protective capability. Periodic inspection may be required to detect compaction loss.
3. Implementation and Marking
Implementation of CAN CSA C22.2 No. 60079-5-16 follows the same certification framework as other CSA Group standards for hazardous locations. Equipment must:
- Be designed for a specific gas group (IIA, IIB, or IIC) and temperature class (T1–T6).
- Be tested by a nationally recognized testing laboratory (e.g., CSA, UL, Intertek) to confirm compliance.
- Be marked in accordance with the requirements of the CE Code and CSA C22.2 No. 60079-0 (General requirements).
Typical marking includes the manufacturer’s name, standard number, type of protection “q”, gas group, temperature class, and the EPL (e.g., EPL Gb). For Zone 2 applications, a simplified construction without all the thermal tests may be accepted if validated with the authority having jurisdiction.
Success: Powder filling is a proven technique for transformers, ballasts, and control devices where simplicity and high ingress protection are needed. The Canadian adoption ensures alignment with the CE Code, simplifying the approval process for equipment installed in Canada’s oil, gas, and chemical sectors.
4. Compliance and National Differences
While CAN CSA C22.2 No. 60079-5-16 is technically identical to IEC 60079-5:2015, the CSA version includes several national differences required for use in Canada:
- Referenced standards — The Canadian standard cites CSA component standards (e.g., C22.2 No. 0, C22.2 No. 60079-0) instead of the original IEC references.
- Ambient temperature range — The default ambient temperature rating is –25 °C to +40 °C (instead of –20 °C to +40 °C in some IEC editions), reflecting the Canadian climate.
- Filling material acceptance — The CSA version adds specific requirements for thermal stability of the powder at elevated temperatures (up to 200 °C), which is important for process industries in Canada.
- Marking and documentation — Bilingual (English/French) markings are required for equipment sold in Canada. Instructions for installation and maintenance must comply with Part 1 of the CE Code.
Danger: Equipment not certified to the Canadian national adoption cannot be legally installed in hazardous locations in Canada. Even if the IEC version is accepted elsewhere, only CAN CSA C22.2 No. 60079-5-16 certified equipment is acceptable for inspection by the electrical authority in Canada. Always verify the certification marks and the standard number on the nameplate.
Frequently Asked Questions
Q: What types of equipment are typically protected by powder filling (type “q”)?
A: Common applications include transformers, current and voltage transformers, ballasts for lighting, capacitors, and control devices where the internal components are likely to arc or heat during normal operation. The powder absorbs and dissipates energy, preventing ignition of the surrounding explosive atmosphere.
A: Common applications include transformers, current and voltage transformers, ballasts for lighting, capacitors, and control devices where the internal components are likely to arc or heat during normal operation. The powder absorbs and dissipates energy, preventing ignition of the surrounding explosive atmosphere.
Q: Can powder‑filled equipment be used in Zone 0 or for Group I (mining) applications?
A: No. The standard explicitly limits type “q” to Zone 1 and Zone 2 gas atmospheres (EPL Gb or Gc). For Zone 0, other protections such as intrinsic safety (Ex i) or encapsulation (Ex m) are required. Group I mining atmospheres are covered by separate Canadian standards (e.g., CSA M421).
A: No. The standard explicitly limits type “q” to Zone 1 and Zone 2 gas atmospheres (EPL Gb or Gc). For Zone 0, other protections such as intrinsic safety (Ex i) or encapsulation (Ex m) are required. Group I mining atmospheres are covered by separate Canadian standards (e.g., CSA M421).
Q: How often must powder‑filled equipment be inspected in service?
A: The standard does not prescribe an inspection interval, but the CE Code requires periodic inspection per Table 24 (usually every 1–3 years depending on the classification). Special attention must be paid to signs of powder leakage, corrosion of the enclosure, or evidence of overheating.
A: The standard does not prescribe an inspection interval, but the CE Code requires periodic inspection per Table 24 (usually every 1–3 years depending on the classification). Special attention must be paid to signs of powder leakage, corrosion of the enclosure, or evidence of overheating.
For detailed test methods and constructional requirements, refer to the full text of CAN CSA C22.2 No. 60079-5-16, which can be obtained from the CSA Group website or through authorized standards distributors.
© 2026 – This article provides an informational overview and does not replace the official standard. Always consult the latest edition of the standard for compliance.