Ex Non-Electrical Certification


It is well known that more explosions are traced to non-electrical sources of ignition than electrical sources. Despite this, for Zone 1 (CAT2) Certification under ATEX non-electrical equipment could be ‘self-certified’ (with the resulting file lodged with a Notified Body but not checked) Since the introduction of IECEx non-electrical assessment this has changed, and all IECEx Certification is conducted by qualified and IECEx accredited Certification Bodies.

Non-electrical equipment can cause explosion by friction, impact, static, hot surfaces and many other methods; all equipment designed to be used in Explosive Atmospheres should have been risk assessed to assure that this cannot happen, but in Europe it is the law that this must be done (under the ATEX Directive) and the methodology for doing the assessment and protecting ignition capable parts has been well defined in the form of ‘Standards’.

Typical Information required to conduct an Ex non-electrical assessment.

A document would be required to confirm the global specification & environment for where the equipment will be used and in what environments (E.g. Zone, Gas Group, T Class, and Ambient Temperature).


The assessment must be made for any part that can could become an effective ignition source (through for example heat, friction, static etc) under specified condition (for example, normal operation for Zone 2, under a malfunction for Zone 1 and under a rare malfunction for Zone 0, so for any Zone other than Zone 2, failure mode analysis is required.

Methods of protection for non-electrical equipment (all referred to as ‘Ex h’) include constructional safety, liquid immersion and control of ignition sources (use of protective systems such as monitoring temperature and having some form of shut down system).


Simpe Example ATEX Non-Electrical Assessment of a ‘bearing’ using constructional safety for Zone 1 or Zone 2

Bearings are selected based on the equipment’s intended duty and the following items would need to have been considered as a minimum.

  • Static load
  • Dynamic Load
  • Speed

From this you can calculate bearing life (many bearing manufacturers have online tools for this with further derating) a suitable replacement time (replace before failure) with an appropriate safety factor can be determined and specified in the user instructions and/or certification.


Other assessments such as the effect of temperature on lubricants etc. will also need to be considered. It should be noted that it is quite common to find lubricants that are not suitable for the normal ATEX/IECEx Ambient Range of -20°C to +40°C

The same assessment would be required for each bearing for Zone 2, as the bearing must be proven to be rated correctly even in normal operation.

For Certification or Training on Ex Non-Electrical Equipment and Assembles you can contact ExVeritas at

The ExVeritas Group provides Product Certification, Management System Certification, Training and CompEx Certification and Site Safety Services. We have fully accredited test laboratories offering explosion safety, electrical safety and environmental testing.

ExVeritas are a UK Government Appointed Body for UKCA ‘Ex’, an ATEX Notified Body and an IECEx Certification Body and Test Laboratory with offices and test facilities in UK, Denmark and North America.

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