This part of IEC 60079 specifies the general requirements for construction, testing and marking of the electrical equipment and Ex Components intended for use in explosive atmospheres

The standard atmospheric conditions (relating to the explosion characteristics of the atmosphere) under it may be assumed that electrical equipment can be operated are:

• Temperature -20 Degrees C to +60 Degrees C
• pressure 80kPa (0.8 bar) to 110 kPa (1.1 bar)
• Air with normal oxygen content, typically 21% v/v

BS EN 60079-29-0 and other standards supplementing this standard specify additional test requirements for equipment operating outside the stanard temperature range, but further additional consideration and additional testing may be required for equipment operating outside the standard atmospheric prrssure range and standard oxygen content, particularly with respect to types of protection that depends on quenching of a flame such as “Flameproof Enclosures “d”” (IEC 60079-1) or limitation of energy, “Intrinsic safety “i”” (IEC 600-79-11)