Essential Performance (EP) initially came into the IEC 60601 series of standards when the 3rd edition of IEC 60601-1:2005 was published. The definition was quite confusing and many manufacturers, regulators and test houses had a hard time with it and how to apply it properly. In 3rd edition (2005) + amendment 1 (2012) some clarification came into play which made it easier to understand but there is still a fair amount of confusion.

About 2 years ago a test lab did some research and brought up the issue that a significant number of test reports (a high percentage of them) of critical devices didn’t define essential performance appropriately to the Sub Committee SC62A on “Common aspects of electrical equipment used in medical practice”. From this research, an ad-hoc group was formed to come up with a solution.

The initial solution was to come up with this Interpretation Sheet (ISH) to explain Essential Performance (clause 4.3 which is not as clear as the ISH but for those that know the standard have been doing it this way for years) and Single Fault Condition (SFC) (clause 4.7) that is related to Essential Performance. Access a copy thru the IEC website if you know where to find it or the easier route is to download it here. Note, this document doesn’t cover all the issues about Essential Performance as it is a complex situation but it does help explain some of the issues involved. The ISH per IEC requirements is limited to 2 pages of written text of explanation allowed by IEC requirements and so has a constraint on how detailed it can get. It is good for explaining the concept for the General standard IEC 60601-1, edition 3.1 which covers also ed. 3.2 (no change there). The General standard concept is based on limits but for some Particular standards (IEC 60601-2-XX or IEC/ISO80601-2-XX), limits don’t work for all products applicable (not all display-based product that the clinical function is based on the display function for example). But the ISH doesn’t really get into the details of how EP deals with Particular standards much (covered a little in the ISH) so that really needs to be looked at further still.

So, what is the next step? This ad-hoc group with the help of some additional people in the standards development community (I hope to be in this group) will start in the next couple of months (probably after the IEC TC 62 General meeting of April 12 – 23, 2021) to work on a guidance document to provide further guidance on EP as I still find that many regulators around the world, test labs, and manufacturers all have varying understanding of what EP & SFC are.

This varying understanding has a huge impact on projects as if say the test lab asks the manufacturer what their EP is, the manufacturer may say I don’t have any, the test lab will check the test report form (TRF) as none. When gets to say FDA the first thing FDA would ask is why is there no EP on the device? If found out there is EP the client would have to retest under the applicable IEC 60601-1, Particular (60601-2-XX/80601-2-XX) and Collateral Standards (60601-1-XX) + the EM Disturbances standard IEC 60601-1-2 which would add cost and time delays to a project.

Need help with Essential Performance. Feel free to schedule a call with Leo www.EisnerSafety.com/Schedule-Call/ or contact Leo at Leo@EisnerSafety.com.

Last summer Amendment 1 (A1) came out and if you haven’t yet you should start learning about those changes as they will be impacting you sooner rather than later (sign-up for an FX Conferences recording of my recent presentation on A1 of IEC 60601-1 and its’ impact on users, follow the instructions to get a $50.00 discount, and sign up for the presentation titled “IEC 60601–1, 3rd Edition, Amendment 1 and its Impact on Users”) and also A1 can help you as it will reduce the amount of Risk Management File work you need to do for a product safety certification or approval. There are about 25 less Risk Management File requirements when using A1 vs using 3^rd ed.  To understand the differences and changes of A1 it is highly recommended that you get the IEC 60601-1 edition 3.1 (consolidated) edition as that shows you where all the changes are to the text vs 3^rd ed.  Note, when you submit for testing thru a test lab you will either want to use either edition 3.1 or 3^rd ed. but you can’t mix and match as that would not work well and any CB scheme certified lab, among most other labs, will not mix and match requirements as it gets messy quickly.

So, what are the current changes to the standards related to alignment with 3^rd ed. & the new Interpretation Sheet?  Let’s start with the standards.

The updates are actually withdrawal of two standards that have been embedded into 3^rd ed. when it was released (i.e. IEC 60601-1-1, 2^nd edition – Medical Electrical Systems & IEC 60601-1-4 Programmable Electrical Medical Systems) and so the 2^nd ed. aligned standards needed to be withdrawn as 2^nd edition of IEC 60601-1 has been withdrawn since the publication of 3^rd edition back at the end of 2005.  The withdrawal report to IEC for IEC 60601-1-1, Edition 2.0 (now in IEC 60601-1, 3rd ed. in clause 16) covered the following 3 points, and it is the same circumstances for IEC 60601-1-4, edition 1.1 (1^st ed. + A1) (now in IEC 60601-1, 3rd ed. in clause 14):

• IEC 60601-1 Ed. 2.2 (IEC 60601-1:1988+A1:1991+A2:1995) was withdrawn in 2005, yet those who want to use it have been able to do so for the past seven years.
• IEC 60601-1 Ed. 2.2 makes normative reference to a number of supporting standards that have been revised or superseded, yet users have been able to find the versions they need to implement Edition 2.2.
• With the changes made in Amendment 1 to IEC 60601-1:2005, there are substantive technical differences between this collateral standard and its respective clause in IEC 60601-1 Ed. 3.1. Therefore, this document can no longer be considered to represent the generally accepted state of the art.

Let’s move onto the Interpretation Sheet 3 (or IS3) for IEC 60601-1 3^rd edition and also for edition 3.1 or 3^rd edition + A1.  It is the 3^rd interpretation sheet issued since IEC 60601-1, 3^rd edition has been issued.  IS3 is a clarification of the requirement for sub-clause 13.1.2, 4^th dashed line which the sub-clause is titled “Emissions, deformation of ENCLOSURE or exceeding maximum Temperature”.  The requirement of concern is:

“The following HAZARDOUS SITUATIONS shall not occur;”

“- ….”
“-     temperatures of ME EQUIPMENT parts that are not APPLIED PARTS but are likely to be touched, exceeding the allowable values in Table 23 when measured and adjusted as described in 11.1.3;”  (This is the fourth dashed line of 13.1.2)

So, this requirement is saying that this situation should not occur (following HAZARDOUS SITUATIONS) if there is a part that isn’t an APPLIED PART (An APPLIED PART is a part of the device that in NORMAL USE necessarily comes into physical contact with the PATIENT for the device to perform its function.  So, a part other than an APPLIED PART) that is likely to be touched that exceeds the temperature limits of Table 23 (Allowable max temperatures for ME EQUIPMENT parts that are likely to be touched) in the temperature test method described in sub-clause 11.3.

The IS3 gives an alternative route to meeting the above requirement by stating the following:

“This is clarified by the following:

The above requirement is regarded as fulfilled in accordance with Subclause 4.5 for temperatures at the surfaces of the enclosure, if the following conditions are fulfilled:

− The maximum allowed temperature on OPERATOR accessible surfaces in SINGLE FAULT CONDITION is 105 °C; and

− the instructions for use contain a warning that, under some SINGLE FAULT CONDITIONS, the temperature of: (indicate the surface of concern) could get hot and there is a possible RISK of a burn if touched, and

− if the RISK ANALYSIS demonstrates a need for a warning symbol on the ENCLOSURE, safety sign ISO 7010-W018 ( ) shall be used on or adjacent to the hot spot on the ENCLOSURE; and

− the RISK ASSESSMENT demonstrates that the temperature attained in the SINGLE FAULT CONDITION is acceptable, and

− the RISK ASSESSMENT demonstrates that applying the alternative RISK CONTROL measures in this Interpretation Sheet results in a RESIDUAL RISK that is comparable to the RESIDUAL RISK resulting from applying the requirement of the standard.

NOTE 1 This Interpretation Sheet is intended to be used with both Edition 3.0 and Edition 3.1 of IEC 60601-1.

NOTE 2 An example of an analysis that demonstrates an adequately low probability of occurrence of HARM is shown below.”

To access this IS3 for free please go to the IEC website link.

If you need assistance with this or other issues, please contact us at Leo@EisnerSafety.com.