Please support IEC Draft TS 60601-4-X before 17th January 2023

Please support IEC Draft TS 60601-4-X before 17th January 2023 image #1

06 Jan 2023

Please support IEC Draft TS 60601-4-X

Vote positive, before 17th January 2023!

It seems that too few people in the world of medical devices or systems have been keeping up with the state of the art in managing “Essential Performance” risks caused by EMI, with the result that IEC Draft TS 60601-4-X might fail to be approved when votes are counted after 17th January.

So, please support this draft by voting positive for it before 17th January 2023.


It became a normative requirement in IEC 60601-1 at Edition 3 in 2015 to use risk analysis to manage the risks of not achieving “Essential Performance” in medical electrical/electronic devices, equipment and systems.

This new risk management requirement flowed down into all standards in the IEC 6060-1-x-y series, which all had to be modified accordingly.

The concept of “Essential Performance” is often a difficult one to understand. I discussed it with one of its original creators, who said that it was necessary because of the inherent untestability of modern digital systems – something that has been known by the safety critical systems industry since the 1970s. I describe it like this:

1.         Programmable digital systems have too many possible digital states to ever be thoroughly tested – even once.

2.         They are also non-linear, so we can’t interpolate, i.e., we can’t test a percentage of digital states and assume that the results prove anything at all about the untested states.

E.g. even if 90% of the digital states tested safe-enough, we must not assume that the untested 10% would also be safe-enough. (And anyway, we can’t usually even test 1% of all possible digital states in any affordable timescale.)

3.         The inherent and unavoidable unpredictability of programmable digital systems is the reason why “Essential Performance” requires comprehensive risk analyses.

And why it is now so very important for the safety of medical electrical devices, equipment, systems and installations.

In 2006, BSI’s CH/62/1 medical standards committee appointed me to IEC 62A/MT23 – the Maintenance Team responsible for the medical EMC safety standard IEC 60601-1-2 EC 60601-1-2 – at the request of MT23 specifically to help them modify IEC 60601-1-2 to manage the Essential Performance risks that could be caused by EMI.

Accordingly, starting in 2006, I helped MT23 develop suitable risk management text for use in what became IEC 60601-1-2 Ed.4:2014.

Despite risk management of EMI being a normative requirement in 60601-1-2 Ed.4, and despite modern programmable digital systems being inherently impossible to fully test (see 1 - 3 above) , MT23 chose to make this new text mere guidance – in Informative Annex F.

Afterwards, for Amendment 1 to IEC 60601-1-2 Ed.4:2014, MT23 developed an improved Annex F based on both the IET’s 2017 Code of Practice on Electromagnetic Resilience, see here; and on IEEE Std 1848-2020, which is a ‘full standard version’ of IET 2017, see here

However, the IEC SC62A National Committees (NCs) voted not to accept this new version of Annex F at AMD1, but then went further by deleting the existing guidance in Annex F!

We in MT23 did not want our valuable and important new guidance on how to manage the safety risks that can be caused by EMI to be lost – so we decided to propose it as a new Technical Specification (TS) for inclusion in the IEC 60601-4-x series of documents.

No IEC TS can create normative requirements, but nevertheless we have very carefully modified its text to avoid any possible hints of new requirements, to try to make it more palatable to the IEC SC62A NCs who had voted against it at AMD1.

It seems that only a few people in the medical devices/systems world understand the above, having not kept up with the state of the art in risk management as regards EMI, so IEC Draft TS 60601-4-X could fail to be approved. So please support this draft TS by voting for it before 17th January 2023.

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