IEC 60079-14 Annex C: New Cable Rules for Explosive Atmospheres

The 6th edition of IEC 60079-14, released in August 2024, introduces significant updates, particularly for electrical cables used in explosive atmospheres. Among the most critical changes is the transition from Annex E to Annex C, bringing new implications for cable selection and testing—especially in hydrogen-rich environments (IIC+H₂).

But what does this mean in practical terms? Let’s break it down.

Previously, Annex E provided general guidance on cable properties for hazardous locations. In the 2024 edition, Annex C replaces Annex E, shifting from a guideline-based approach to a mandatory regulatory framework. This means that compliance is no longer a recommendation—it’s a requirement.

Key Changes:

• New pressure testing requirements determine whether cables permit gas migration, replacing the outdated assumption that certain cables could inherently prevent gas transmission. The objective? To assess how cables interact with gas under operational conditions.
• Selection of Ex d cable glands is now directly tied to these test results, especially for hydrogen applications (IIC+H₂).

How Does the New Pressure Test Work?

• A cable sample is exposed to pressurized gas.
• Gas migration is measured over time to evaluate permeability.
• If gas movement is detected, the cable is not suitable for Ex d applications unless additional sealing measures are applied.
• Test results determine whether a standard compression gland is sufficient or if a barrier gland with individual conductor sealing is required.

Hydrogen (H₂) is classified as IIC, the most demanding gas group in terms of explosion risk. Due to its low molecular weight and high permeability, hydrogen can migrate through certain cable materials, making traditional assumptions about gas tightness unreliable.

To address this, the new Annex C mandates pressure testing to evaluate gas permeability in cables. If a cable fails the pressure test, additional sealing measures are required to prevent gas migration.

Hydrogen-rich environments (IIC+H₂) now have stricter guidelines for cable length before testing is required:

>3m cable length for standard IIC environments.
>0.5m cable length if the enclosure volume exceeds 2000 cm³.

Gas-Tight Cables? Not an Official Definition!

Did you know that IEC 60079-14 Annex E never officially defined "gas-tight" cables? And neither does the new IEC 60079-14 Annex C! The term "gas-tight" was primarily coined for marketing purposes to clarify the use of cables suitable for explosive atmosphere installations, but it is not an official technical definition.

Although widely used by cable manufacturers, installers, and engineers, it's important to remember that when requesting a "gas-tight" cable, you should also specify the relevant standard and the type of installation it will be used for.

Staying Updated and Maintaining High Standards

The shift to mandatory testing and stricter requirements, underscores the need for ongoing vigilance in maintaining safety and compliance. At Camuna Cavi, we are always at the forefront of these changes, committed to upholding the highest production and testing standards. By prioritizing quality and staying updated with industry developments, we ensure that our solutions continue to meet the most demanding safety requirements, keeping your installations secure and compliant.