EBME Forums Forums Maintenance Technical Assistance Electrical Safety Test (IEC 601-1) Failed

I have a company who wish to trail a new patient monitor. Class 1 / CF (AP: 5).

I have carried out Electrical Safety Test (IEC 601-1) to the unit. It Failed.

It failed on Insulation Resistance AP – Case

AP-INSUL. RESIST. [MOHM]
ALL-CASE 33.0F [ 50]

What I am trying to find out? has the standard changed at all. The company wrote me a letter

Company Quote:
Under IEC 60601 the ECG insulation resistance test is viable test for manufacturing purposes only, and as such it has no documented pass or fail criteria, customers and users alike are requested to contact the manufactures to ensure the readings they obtain fall within the manufactures specifications.

I checked Biotek manual to see the standard which was 50 Mohms.

They showed me a print out from own Biotek test results, which the unit had passed.

AP-INSUL. RESIST. [MOHM]
ALL-CASE 33.0 [ 2]

There 601 standard was different and set to 2 Mohms.

I need help. Can I use this machine or not.

I thought the idea of standards was to keep it all the same.


Thank you

A.M

If that monitor is used via an isolating transformer then test it through the transformer and it will pass. I recently had to 601 test a video monitor and it failed the same test but as it used through an isolating transformer I was advised to test it through that and it's OK.

Not sure if we're talking about basic mains insulation, here, Aston, or the dreaded mains on applied part(s). But as you mention Meg-ohms, I'm assuming it's the former.

But we are talking about a patient monitor here, right? Then in my book it fails, pure and simple. If it were me, I would reject it! And, perhaps more importantly, I would like to hear from the manufacturer why that insulation resistance is so low. Switched-mode power supply would be my guess. Is this really progress, or are the rules (time-honoured rules at that) being massaged to suit modern equipment design? If it was deemed unsafe to be less than 50 Meg before, why should it not be the case today? Or were those thousands upon thousands of (earlier) electrical safety tests just a gigantic waste of time after all?

If this bit of kit needs an isolation transformer (which is not in itself such a bad thing), then it should be built-in to the equipment itself, in my opinion.

Together with basic mains insulation, and grounding continuity, my own preferred test is enclosure leakage under SFC (ie, with ground open), as I believe that this gives the maximum worst-condition "risk current" (touch current) that could result in a practical (real-world) scenario (eg, mains to "chassis" due to internal component failure, plus a badly wired, or broken, mains plug). Anything above 0.5 mA would constitute a failure. Why not give that one a try (perhaps you already have)? Then that would be the clincher!

I should more specific. The unit under test is a portable ECG monitor with NIBP, SPO2 and temperature.

What I am trying to find out version of IEC 601-1 is correct.

My Biotek 601 has the standard for Insulation Resistance AP – Case set to 50 Mohms.

Trail companys Biotek 601 has the standard set for 2 Mohms.

The Biotek user manual stated that the test should be 50 Mohms.

I am still waiting to go on the Seaward seminars on the new regulations.

I have failed the UUT until I get a good enough argument to tell me other wise.

Thank you for your help

A.M

Just to clarify - IEC62353 is not a regulation, it's an international testing standard (that's not yet adopted by BSI as far as I'm aware) that can be voluntarily applied to the routine testing of medical devices by organisations, e.g manufacturers and service agents. Being an IEC standard that's not yet harmonised, thus ratified by BSI, yet, it's not necessarily applicable i.e. the use of such a standard is not mandatory in the UK/EU.

Saying that '60601-1 doesn't specify insulation resistance checks but IEC62353 does, which is very useful in my opinion - it gives applicable IR testing. Consider a device with poor isolation of BF or CF applied parts to earth (from manufacture)and also relatively poor isolation, mains parts to earth, under SFC (Earth O/C or mains on applied parts) then the possibilities of excessive leakages to applied parts from earthed enclosure are more likely than not.

IR tests enable tests to be applied before the device under test is powered-up with potentially lethal mains. They're useful if someones spilled conductive fluid into, or there's been damage to, a device in service and isolation has been compromised, for example.

'60601-1 does give limits for patient leakage via applied parts under NC and SFC. What are the results of the safety test under NC and SFC, neglecting the results of the IR test then Aston Martin? I'd be interested in looking at the patient leakage with earth O/C and with mains on applied parts. These are SFC checks that should result in higher leakages if there is, relatively and generally speaking, poor electrical isolation between applied parts and Earth.

Remember the device must pass IEC62353 AND 60601-1 when the IEC62353 standard is adopted/accepted/harmonised by the UK/EU standards organisations. Be interested in seeing all your results of testing, i.e. the applicable leakage (enclosure, patient and earth), ac and dc leakage currents, under NC and SFC, mains F/R, i.e. the results of applicable '60601-1 (2nd edition I assume) tests, irrespective of IR.

If it's any use my advice would be to apply IEC62353 (which has a limit for IR, AP-Earth, of 70MOhm I believe). Hence see what the manufacturer of the device then argues? Lets see whether '60601-1, i.e. type-tests, can co-exist with recurrent test standards and ensure an "equivalent safety standard", eh?

AM

I would take very simplistic view.

As a medical engineer you are employed to protect the Trust and its patients from any (technical) hazards arising from the use of medical equipment. That includes actively descriminating against equipment offered to the Trust, which by the suppliers own admission, has safety limits set 25 times lower than previously offered products!

I find it disturbing that in these increasingly litigious times a supplier/manufacturer is willing to put onto the market equipment which so blatantly degrades the degree of protection offered to the patient.

Presumably in your trials of equipment you have tested other offerings which have passed your safety test with comfort. If these manufacturers can design equipment to an acceptable level then anyone should be able to.

My attitude would be to tell your problem supplier to remove his equipment forthwith and to return only when he can satisfy YOUR standards and those of YOUR Trust in providing a safe environment in which to treat patients and staff.

If the supplier is reading this forum then I would ask that they do not take the trouble to visit Calderdale and Huddersfield NHS trust.

Brian

Bravo!

I agree - personally I'm not keen on manufacturers hiding behind standards just because some fundamental aspect such as IR is not included in the device-specific manufacturing standards. However, if they want to do that there's always another standard that we can use to argue the case.

In fact I have had discussions recently with a company (device on evaluation/loan) that insist a product of theirs (1 BF) is perfectly safe with IR (AP-Earth) of around 6MOhms (and this varies in 3 devices, 9MOhms, 6MOhm and 3MOhms, or so).

Considering the intended use, application, use of conductive fluids in the patient applied part that's in electrical contact with the device and possibility of ingress, etc, I'm not convinced that there won't be degradation in IR - in spite of the device passing patient leakage checks.

In Aston Martin's position I'd reject and insist on a more meanigful justification for the reasoning behind manufacturing a product with relatively low IR (AP-Earth) and also I'd want to examine the results of a safety test that includes NC and SFC conditions that're applied correctly to individual applied parts.

I have not even let the ECG monitor be use by hospital staff in Sale Rep demonstration. I have to protect myself, staff and patient against questionable medical equipment.

Today the company sent a service engineer to carry out EST the ECG monitor. It failed there own EST. The ECG monitor passed the other parts of the safety test with no problems. The company is running two different IEC 601-1 standards.

Workshop engineers are using a lower standard: 2 Mohms

Field engineers are using higher standard: 50 Mohms

The other trail company have all passed with flying colours.

I did tell both sale rep and workshop engineers that I would be posting, and asking for help.

Thank you for all your help.

A.M

Time to name and shame, I reckon!