prEN IEC 60079-42:2024

This part of IEC 60079 specifies the construction and testing of electrical safety devices to reduce the likelihood of potential ignition sources becoming effective in Ex Equipment located in Explosive Atmospheres. In the context of this document electrical safety devices perform a safety function to control potential ignition sources from both, electrical or non-electrical Ex Equipment in explosive atmospheres.
In the context of this document, a safety device could be an element of a safety function, for example, sensor, logic or final element, or a combination of elements performing a complete safety function.
A safety function can be a manual or an automatic action.
This document can also be used for assessing the safety device independently, without being designed for a specific Ex Equipment.
A safety device can be a measure to achieve a required Equipment Protection Level (EPL) of the Ex Equipment with respect to a potential ignition source. The combination of the safety device and the Ex Equipment could then comply with the relevant standards of the IEC 60079 series and the ISO 80079 series with respect to the Equipment Protection Level. Increasing the
167 EPL of Ex Equipment by the simple addition of a safety device is not within the scope of this document.
This document does not apply to:
• mechanical control equipment such as pressure relief valves, mechanical governors and other mechanical safety devices;
• the use of gas detection;
• safety devices to prevent the occurrence of explosive atmospheres, for example inerting systems, pressurization systems and ventilation systems; or
• mitigation of an explosion.
NOTE Some potential ignition sources might not be practicably controlled by safety devices.
For electrical safety devices, where the level of safety integrity is identified under other parts of the IEC 60079 series, this document can be used as a reference for the realization of the level of safety integrity.
Electrical safety devices could be installed either as part of or separate to the Ex Equipment under control (ExEUC) and could be located inside or outside the hazardous area.
This document is not applicable where another Type of Protection requires a Specific Condition of Use for a safety device but does not reference this document. For example an overload protective device for and Ex “e” motor.