EN/IEC 60079-0 specifies the basic requirements for electrical equipment intended for use in explosive atmospheres at standard atmospheric conditions and the ‘normal’ ambient temperature range for Ex equipment is generally given at as –20 °C to +40 °C unless marked otherwise. 

IEC 60079-14 (selection and installation of Ex equipment) also includes requirements for users to select and install equipment so that it is suitable for the ‘environmental conditions’ but does not provide any specific guidance for installations outside of the standard conditions. 

IEC/TS 60079-43:2021 has been produced to address this, it is a guide for ‘Ex’ equipment subject to adverse service conditions such as low temperature, humidity, corrosive media, powder snow, precipitation, spray from waves, high winds, solar radiation, and mechanical effects.

Examples of issues

If you take as an example of a severe service condition Low temperature effects, the following may be relevant and should be considered: 

Electrochemical capacitors may freeze and fail which could affect intrinsic safety.  Humidity can also affect creepage and clearance. 

Protective compounds may become solid and crack, this could affect potting for intrinsic safety or encapsulation Ex m)

Rubber materials may lose elasticity and fail; – This could affect gaskets which may be critical in Ex e or Ex t 

Greases may freeze and oil viscosity increases restricting flow, this may adversely affect Ex h.

embrittlement of materials or welded joints may occur, this affects all enclosure-based concepts and particularly Ex d

differential expansion or contraction of materials may have an impact on correct fitting of components which can affect Ex d flarepaths and Ex h mechanical friction. 

It should be noted, for example, that a lot of ‘self-certified’ mechanical equipment is certified with an assumed ambient temperature range of –20 °C even though the lubricant used are only suitable for temperatures above freezing!

Who needs to know this?

Under both ATEX and UKCA Certification the manufacturer must assess and mitigate all risks under the Essential Health and Safety Requirements that they declare they have met. The Specifier and Installer must also be aware of any special service (environmental) conditions when selecting and installing Ex equipment, so all parties need to be aware of the possible implications of a best practice standard such as IEC/TS 60079-43.

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