CAN/CSA C22.2 No. 60079-7-16: Equipment Protection by Increased Safety ‘e’ for Explosive Atmospheres

Scope and Application

CAN/CSA C22.2 No. 60079-7-16, titled Explosive atmospheres – Part 7: Equipment protection by increased safety “e”, is the Canadian adoption of IEC 60079-7:2015. It forms part of the CSA Group’s suite of standards for electrical equipment in hazardous locations and harmonizes with the Canadian Electrical Code (CE Code, Part I).

The standard specifies requirements for the design, construction, testing, and marking of electrical equipment with type of protection “e” (increased safety). This protection concept applies to equipment that, under normal operating conditions, does not produce arcs, sparks, or hot surfaces capable of igniting an explosive gas atmosphere. Increased safety measures provide a higher degree of security against the possibility of excessive temperatures and the occurrence of arcs, sparks, or hot surfaces during normal operation.

Applicability: The standard covers Ex e equipment intended for installation in Zone 1 or Zone 2 hazardous areas where explosive gas atmospheres may occur. It includes a wide range of equipment such as:

• Terminal boxes and junction boxes
• Lighting fittings
• Motors (induction, synchronous, and DC)
• Resistance heating devices
• Current-carrying conductors and connectors
• Control and instrumentation enclosures

Excluded from the scope are equipment that inherently produce arcs or sparks in normal service (e.g., switches, relays, fuses) unless they are integrated within an Ex e enclosure and evaluated for additional measures. Portable or handheld equipment and equipment with rated voltages above 11 kV are also excluded.

Technical Requirements and Protection Principles

The increased safety “e” method relies on preventing the occurrence of arcs, sparks, and hot surfaces under normal operation. Key technical requirements are divided into general provisions and equipment-specific clauses.

General Requirements

• Temperature Classification: The maximum surface temperature of any Ex e component must not exceed the temperature class (T1 to T6) declared for the equipment. Temperature classes are based on the lowest ignition temperature of the surrounding gas or vapour.
• Ingress Protection (IP): All enclosures must have a minimum IP rating of IP54 (for gas groups IIA, IIB) or IP65 (for Group IIC, hydrogen/acetylene). The IP rating prevents ingress of dust and water that could compromise insulation or cause corrosion.
• Rated Voltage and Insulation: Insulation systems must withstand the rated voltage plus a safety margin. Creepage distances and clearances conform to specified values dependent on voltage, pollution degree (PD), and material group.
• Connection Terminals: Terminals must be designed to prevent loosening, maintain contact pressure, and provide adequate creepage distances. Conductor cross-sections must match the rated current and temperature rise limits.

Table 1: Key Technical Parameters for Ex e Equipment (Extract)

Equipment-Specific Requirements

• Ex e Motors: Additional requirements for starting performance, locked-rotor current (I_A/I_N ratio), and the time t_E required to reach the temperature class from cold start with locked rotor. Temperature sensors (e.g., PTC thermistors) may be required for large motors.
• Ex e Lighting: Luminaires must enclose all arcs and sparks; lamp replacement requires special measures. Thermal protection of ballasts is mandatory for fluorescent and HID types.
• Ex e Junction Boxes: Internal wiring must be arranged to prevent condensation and ensure effective drainage. Cable entries must maintain the IP rating and be third-party certified.

Implementation and Design Considerations

Designing equipment to meet the requirements of CAN/CSA C22.2 No. 60079-7-16 involves a systematic approach to thermal management, electrical insulation, and mechanical integrity. The following aspects are critical for successful implementation:

• Material Selection: Enclosure materials must be resistant to the expected chemical environment, UV exposure, and mechanical impact (at least 7 Nm for light alloys). Creepage and clearance distances are affected by the comparative tracking index (CTI) of insulating materials.
• Thermal Analysis: Determine maximum internal temperatures at rated load and ambient temperature (typically 40°C). Verify that all components stay below the temperature class. For motors, the t_E time and starting current must be declared on the nameplate.
• Interconnection with Other Protection Types: Ex e equipment may be combined with other types (Ex d, Ex i, etc.). For example, a flameproof enclosure (Ex d) can contain Ex e terminals. The standard provides guidance on interface requirements.

Testing and Certification

Type testing is required for compliance and includes:

1. Temperature rise test at rated load and locked-rotor (for motors).
2. IP rating test per IEC/CSA 60079-0.
3. Insulation and dielectric strength test (20% higher than rated voltage, 1 min at 50/60 Hz).
4. Mechanical impact test (7 J for light metals, 4 J for plastics).
5. Verification of creepage distances and clearances.

Certification bodies in Canada (e.g., CSA, UL, Intertek) certify Ex e equipment under this standard. The certificate number and year mark (e.g., CSA 19CA12345) must appear on the equipment nameplate.

Compliance and Certification Notes

In Canada, electrical equipment used in hazardous locations must comply with the CE Code, Part I (CSA C22.1) and the relevant Part II standards, including CAN/CSA C22.2 No. 60079-7-16. Key compliance points include:

• Authorities Having Jurisdiction (AHJ): Provincial and territorial authorities may require certification by an accredited certification body (e.g., CSA, QPS, Intertek). A valid certificate of compliance must be kept on file.
• Field Labeling: Equipment imported or manufactured without third-party certification may be eligible for field evaluation by a recognized inspection body, following the requirements of this standard.
• Marking: The nameplate must include: manufacturer/agent name, standard number (CSA C22.2 No. 60079-7-16), Ex marking (e.g., Ex e IIB T4 Gb), certificate number, temperature class, ambient temperature range, IP rating, and electrical ratings.

Documentation Requirements

The manufacturer must provide technical documentation demonstrating compliance, including design drawings, thermal calculations, test reports, and quality system records (e.g., ISO 9001 or CSA S620). This documentation must be available on request to the certifying body or AHJ.

As of 2026, the standard continues to be referenced by the CE Code and is considered equivalent to the current international edition (IEC 60079-7:2017 with amendments). Users should verify that any amendments (e.g., A1:2020) are incorporated in the CSA version.

This article is intended for informational purposes and reflects the standard status as of 2026. Always refer to the published CAN/CSA C22.2 No. 60079-7-16 document for authoritative requirements.