EBME Forums Forums Maintenance Technical Assistance 62353:2008 - Medical electrical equipment.

I must have missed this one. I have not heard of Biomeds not following recognised international standards? It has long been practised for biomed to follow known international standards and I have not heard of any known individual questioning it. Now that 62353 has emerged, we have to decide if we are following 60601-1 or otherwise. Isn't 60601-1 a more stringent standard than 62353? Without 60601-1 will there be a 62353? The answer is rather clear!

As I say, it's an evolutionary process (just take a glance at JB's avatar)!

HTM-8 ... BS 5724 ... 62353


But ... let's not forget the American approach (which may still prevails in many parts of the world, although all manufacturers should be complying with IEC 60601-1 by now).

By the way, I have heard that it was not only the UK Experts who voted against harmonization of 62353. Apparently, representatives from Italy were unhappy, as well. For those who may not be entirely au fait with this issue, 62353 was developed from DIN VDE 0751, which has been used in Germany and Austria for a number of years.

Here is another link (hopefully not entirely unrelated) which may be of use to those with international interests.

Rodger you seem to miss the point. IEC 60601 is a type test standard used by manufacturers to bring a device to market, it was never designed to be used for routine testing or testing after repair. IEC 62353 (derived from VDE 0751) was and is the only official standard for testing medical electrical devices that are "in service" and for use after repair.

The choice for most is a simple one but some seem to have a lot of difficulty accepting it! This is no doubt the reason the UK and Italian members have an issue with it.

Again I call on anyone who was on any committee dealing with IEC 62353 to come out with their technical objections so we can clear the air but I doubt we will ever hear from them as I don't feel they had any real evidence against 62353. Whereas I have real evidence of faults captured since adopting 62353 that would have been missed in a normal 60601 test!

Surely by now everyone must have taken on board that 60601 is (and has in fact always been) the manufacturing standard, and that 62353 is the one to follow for routine testing of in-service equipment. You could also say that 62353 has evolved as a sub-set of 60601. Hence there is no "choice", as such, as 62353 is the only one actually aimed at routine testing, or testing after repairs have been carried out.

With all it's imperfections (whether real or imagined), 62353 (and it's successor which will surely follow in the fullness of time) is the one being adopted throughout the world. And quite rightly too, if only to save working technicians having to come up with their own practical "versions" of 60601.

Meanwhile (to my mind), there is nothing wrong with carrying on with the sub-60601 mind-set (and 60601-based electrical safety testing instruments), as by-and-large, it approximates (or can be adjusted to approximate) to 62353 anyway.

My main beef is why the Regulating Body in the UK can't just come out and (once and for all) require compulsion on this issue. But, there again, I feel the same about PM as well. I know this can never happen, of course, as any government would then have to address the issue of the proper funding and increased manning of hospital biomed techs that would arise from legislation. I've never much been in favour of mere "guidelines" ... what we need (in my opinion) are clear and unambiguous regulations!

OK Mike, let me be the first to challenge you on that one! How can that be?

Easy, if you only go by the absolute limits as set down in 60601 (or even those in 62353) then you will miss potential failures. This is because you will not compare the test results with that of previous tests as this is only a requirement or 62353, not 60601.

When ultrasound probes were tested by simply observing a pass or fail to the 60601 limits, engineers did not spot when the leakage was increasing so indicating a potential fault. Probes normally measure <4uA on a routine test but when they begin to fail the leakage increases and as soon as this exceeds 1.5 times the initial (previous) value they are deemed to have failed. (We have found a typical value for a faulty probe on it's way to total failure is between 35uA and 500uA.)

Due to the large numbers of tests required by 60601 engineers were selectively choosing tests to perform but these would not always stress the probe to find insulation faults. The simple 62353 tests took away this potential for error and has led to better testing and therefore the location of more faulty probes.

You may say that you already do this, as an experienced engineer, while working to 60601 but it is not written down anywhere and so is not always done. 62353 requires this sort of comparison is made and is therefore safer and more likely to find faults. Since the tests in 62353 are much quicker there is a time and cost saving, allowing time to do the comparison checks which will be more productive than performing the extensive and time consuming 60601 tests.

OK, so your point is making the comparison with previous test results. Plus the secondary one about freeing up more time (hopefully to be used in a more thorough examination of the equipment under test).

Sounds to me like you're used to working with blokes with the "monkey see, monkey do" mentality, there, Mate. I'm glad I don't allow myself to work in an environment whereby I only do what's written down for me to follow!

If techs were testing probes all day, how come they didn't spot higher than usual leakage, whatever test protocol they were meant to be following?

Sorry, Mike. It's not the Standard per se that has found those faults, it's just that you've curbed some of the hitherto sloppiness (laziness?) of the techs!

But it was only because we had a standard to follow that was monkey proof the faults were found.

Experienced engineers like yourself are becoming fewer and fewer these days so we have to have standards and procedures in place that are easy to follow, quick and simple for our new replacements.

As you are quick to point out this forum has contributors from all over the world, so it is our duty to help them with the best tools available for the job and if the job is electrical safety testing of medical equipment 62353 is that tool!

Yes, if I was setting up a new biomed workshop, or engaging in a new contract, or (indeed) was asked to make a recommendation, 62353 would be the one. To use the vernacular for a moment, "it's a no-brainer"!

Meanwhile, Doom on Baboons (they have no business in biomed)!

In defence of the primates, they may not come from a medical background.

It is easy to find the experience and knowledge if you work in, or have worked in, a hospital EBME, Biomed or Medical Physics department but not so easy if you come into the medical field via an equipment supplier as they tend to want you out earning money for the company ASAP!

This can lead to a lack of knowledge and understanding for the peculiarities of medical devices, especially in the testing for electrical safety.

I am glad you support the use of 62353 as this is the best way to ensure we all work to a safe and easily implemented standard. Lets just hope the Americans take it up as then there will be a wider choice of suitable test gear to choose from.