Understanding IEC 60079-11:2023: Major Changes in Enclosures, Connections, and Encapsulation Chapters
Before we delve into the specifics, let’s explore the purpose of this blog series. What led us to create a blog series introducing the new IEC 60079-11:2023 standard requirements? The answer is simple: our aim is to provide you with a comprehensive guide to this revamped standard.
Initially conceived as a non-technical editorial update of IEC 60079-11:2011 (Edition 6), Edition 7 evolved into a technical revision due to various interpretations and comments. The transition brought about 45 significant technical changes, 76 extensions, and 52 minor editorial adjustments. Given the volume of these changes, we cannot cover them all in one blog post.
Join us as we explore the major alterations in the chapters we have highlighted.
Significant General Changes Spanning Multiple Clauses
Let’s start with changes that are in connection with multiple chapters. Some definitions have been removed from Edition 7 because they are now included in IEC 60079-0. For example, terms like ‘coating,’ ‘countable faults,’ ‘non-countable faults,’ ‘encapsulation,’ and ‘casting’ fall into this category. Additionally, some definitions were deemed unnecessary for inclusion here and have been removed, such as ‘fault’ and ‘infallible separation.’ New definitions have been added to Clause 3, including ‘spark test apparatus’, ‘non-hazardous area accessory’, and ‘transient rating’.
As a result of the document’s re-arrangement, there have been changes in the numbering of the tables, which are illustrated in the following table:
Thermal Ignition Compliance and Conditions for Assessment Requirements in Edition 7
Products must fulfil two basic criteria: spark ignition and thermal ignition requirements. The IEC 60079-11:2023 specifies in detail the assessment conditions, like Um, Ui, Ii, and Pi applications. It is essential to consider the service temperature when meeting these requirements and conditions. [Clause 5.2.1]
General Information about the Conditions
’Intrinsically safe circuits shall not be capable of causing ignition under the most onerous conditions, except where permitted elsewhere in this document.’ – IEC 60079-11:2023
Edition 7 provides examples regarding standard heating practices. It is important to take into account the closely located series or parallel components that may carry fault currents. Additionally, testing for heating above the service temperature is not a relevant method, as the most challenging service temperature should be used for testing.
Changes in Thermal Ignition Compliance
According to the new standard, the power dissipation in tracks or wiring should not be more than 1.3W for temperature classification T4, in case of ambient temperatures up to 40°C. If the Tamb exceeds 40°C, the power limits must be reduced as specified in IEC 60079-0, Table 4. [Clause 5.4.1]
The wire thermal assessment formula has been corrected in Edition 7. [Clause 5.4.3]
The Intrinsic Safety proficiency assessment was conducted under IECEx. In light of the changes introduced in the new standard regarding thermal ignition compliance, it is essential to review and validate any products that were previously certified under older standards. Ensure that your products meet the updated requirements and comply with the latest regulations to maintain safety and performance standards.
IEC 60079-11:2023 Requirements for Enclosures of Equipment
To ensure compliance for Group IIIC, it is crucial to verify that the enclosure satisfies the separation requirements stated in Tables 7, 8, and 9. The level of protection necessary depends on the specific table being followed, unless the protection level is assured by separations and not the enclosure:
- For Table 7, a minimum of IP5X is required
- For either Table 8 or Table 9, at least IP54 is necessary
If the separation is reduced, the enclosure must still provide a minimum of IP54 and include any Specific Condition of Use, such as cable glands, thread adapters, and blanking elements, that maintain the IP rating in the certificate. [Clause 6.2.4]
Changes to Internal Connections and Connectors
The previous version of the standard did not differentiate between faults in internal connections. Edition 7 clarifies the distinction between countable faults (based on available data using IPC standards) and non-countable faults. These distinctions are applied to Levels of Protection ‘ia’ and ‘ib’. [Clause 6.4.1]
Another significant change in IEC 60079-11:2023 is the requirement that circuits must remain intrinsically safe even after complete disconnection of a connector, applicable to connectors not considered infallible. A connector is considered infallible when it comprises at least 3 independent connecting elements for ‘ia’ and 2 for ‘ib’ with current-carrying details specified in Edition 7. While some previously certified products may already meet this requirement due to IECEx standard practices (redundancy), we recommend verifying your certified product. [Clause 22.214.171.124]
The implementation of new copper thickness requirements for PCB tracks and vias is crucial for achieving infallible connections. [Clause 126.96.36.199]
IEC 60079-11:2023 Updates in the Separation of Conductive Parts
The most notable change in this chapter is the inclusion of Dielectric Strength test voltages, which were absent in the previous edition. Additionally, what was once an annex – the Reduced Separation Table 8 – has now become an integral part of the standard. [Clause 188.8.131.52]
Furthermore, Edition 7 outlines the required type and routine tests, versus Edition 6, which merely referenced other standards. It provides clarity regarding when each test is applicable. Notable examples include the casting compound and PCB coating tests for reduced distances. [Clause 184.108.40.206, 220.127.116.11, 18.104.22.168]
Existing certified Ex Equipment that relies on reduced separation will need to undergo reassessment and testing as required, following the tests now clearly specified in the new edition of the standard.
Encapsulation in IEC 60079-11:2023
’Encapsulation may be applied by casting, pouring or moulding.’ – IEC 60079-11:2023
The implementation of a routine inspection requirement has been deemed necessary for encapsulated parts to ensure the acceptable application of the encapsulant during manufacturing. From the manufacturer’s perspective, this is of utmost importance as it allows them to exercise control over the verification procedure. To comply with this obligation, a quality audit is mandated, alongside the QAR requirements which serve as the practical implementation of the verification method. [Clause 6.6.1]
In Edition 7, it is imperative that the Continuous Operating Temperature (COT) of the encapsulant remains within the regular operational requirements. Any deviation from this requirement would necessitate stricter obligations. This implies that the compound must not display any visible damage, and the IEC 60079-11:2023 provides examples of potential damage. [Clause 6.6.1]
Furthermore, if intrinsic safety depends on the encapsulant, the standard requires more profound specification of material parameters [Clause 6.7], such as
Pre-treatment of surfaces
Encapsulant name and trademark
Colour of the material
In this overview, we covered five major changes in IEC 60079-11 Edition 7. Stay tuned for future blogs where we will summarize 11 other significant modifications. Until then we suggest you read our previous piece about IECEx and ATEX Certification. Feel free to book a meeting with our CTO on our website or ask our engineers via email for assistance in obtaining your certificate as per the IEC 60079-11:2023 standard efficiently.