Hye friend,

I doing a safety test for one unit of CO2 laser, modeled QrayFRX. The test standard I used was IEC601-1, and I put under class 1, type BF.

The results that I got was failed. When I refer to the results, the measurement that failed are;

Earth leakage current NC - (limit value=0.5)- (result=1.704mA)
Earth leakage current SFC - (limit value=1.0)- (result=2.627mA)

How come this test can failed, what are the condition that can contributes to it....

I really hope anybody can helping me resolve this matters.,,,

What was it like on the insulation test?

I'm just guessing here ... but what mains voltage are you on there? Has the unit been converted to run from (say) 110 to 220 volts? That is, has yet another big transformer been added? If so, that's where I would start looking.

Otherwise, and assuming that the mains cable is in good shape (is it?), I think I would start taking a close look at transformers and big capacitors.

But bear in mind that "big kit" like this (and ultrasound units, and anything else drawing relatively hefty amounts of power), are almost bound to have "noticeable levels" of leakage current. It's just a question of getting them to behave themselves long enough to achieve "readings of comfort". Sometimes (and if you're really keen) it can mean resorting to adding extra earthing straps and the like. Or, failing all that, powering the beast off an isolation transformer. Good Luck!

Hi

Pass / fail limits for equipment containing Laser are specified in the specific standard (ie IEC 60601-2-22)
The alowable P/F limits are higher then the general standard (ie IEC 60601-1). This is also the reason why the 3rd edition now specifies 5mA normal and 10mA SFC limits for all equipment.

You can always contact the manufacturer and ask them to which IEC 60601 conditions the equipment was tested ie IEC 60601-1 and IEC 60601-2-22.
Hope this helps

So Mammad's Laser actually "passed", then. A case of the "wrong" standard being applied, perhaps.


Perhaps you had better clarify that, John. Third Edition of what ... 60601-2-22?

Any idea what the allowable leakage currents are for ultrasound systems ... something similar (the same)?

I must admit, though, that those currents (5 mA, 10 mA) sound a bit on the high side when one is used to "traditional" biomed values. Sounds a bit like changing the rules to make it fit, to me. Aren't the potentially hazardous situations still there, patient-wise? Milli-amps are still milli-amps, regardless of how difficult it may be for manufacturers to meet such stringent requirements.

Hi Geoff,

I agree with you. The limits for earth leakage have increased 10-fold which I have questionned with my fellow IEC committee members. However, from safety point of view, Enclosure leakage open earth SFC is still 500uA (ie 2nd edition earth leakage limit). So this should prevent hazardous currents on the enclosure / patient being allowed.

With 3rd edition, I referred to IEC 60601-1 not IEC 60601-2-22.

I cant comment on whether an instrument passed or failed without knowing what the manufacturer specifies for this instrument. There are 58 specific standards within IEC 60601-2 and i dont know them all inside out hence I do not want to comment on the appropiate limit.

All I know is that not all medical equipment should be passed / failed to IEC 60601-1 but that manufacturers should recommend what the limit should be based on the design of the instrument.
Perhaps the 500uA is the correct limit, then the equipment should fail but without knowing the design, (read manufacturer recommended limit), it is difficult to tell.
Hope this helps.

H'mmm ... it all smacks of a kludge to me, I must say. Has human evolution now taken us to the point whereby we all have a "perception threshold" ten times higher than earlier homo sapiens then?

Why should we care overly much what the manufacturer says and does? How does any of that affect patient safety in the real world? If he (the manufacturer) has got it wrong, then let him recall his machines!

Meanwhile, perhaps what would be really useful is a spreadsheet listing equipment (in generic terms) alongside which contemporary standard needs to be followed during acceptance testing and routine maintenance?

Great idea.
send me a copy when you are done

Ahem! <cough> ... that's not really what I had in mind.

I rather thought someone, shall we say, more knowledgeable on these matters might already have such a document in hand. Do we know anyone like that, John?

I'll keep an eye out for some one who has some spare time to do the research (ie scroll through all IEC 60601-2 standards). You wouldn't know anyone with some spare time would you, Geoff?

Time is all any of us has, John. I value mine, and always try to make best use of it. But, having said that, I remain generally available for consultancy projects at £ 25 an hour!

Back to the original quaestion. You could check the mains inlet filters.

That's good value for money I say. I'll bear that in mind in case we need to do some market research. I presume your price includes VAT?

Yes Bill, but (having looked again at the results Mammad gave), frankly, I doubt that there is a "fault" as such. That is, those figures could well be typical for equipment of that type.

Has anyone else checked out a piece of kit like this?

No need to worry about VAT, John. I don't make enough. But cash would be fine.

I don't think the patient should come into contact with the devise itself, as the applied part would be the lazer, also beleive that IEC601-1 was realy a standard for manufatures that biomeds have embrased for routine testing. I beleive that there is a more apropriate standard in the pine line. I also think that you have to accept that the nature of some equipment means that there may be unavoidable risks that would be unaceptable with other equipment.

Also what is Kludge?

As you are conducting 'In Service' testing then I suggest you use IEC 62353.
If so the unit has failed the leakage test as it exceeds the limit values (unless it is a piece of fixed equipment with no mains plug then 5mA allowed).

Of course if you had been using IEC 62353 you would have had previous results to compare with to help confirm you failure diagnosis!

Systems, such as portable x-ray equipment, that have mineral insulation are allowed to have a higher leakage value (2.5mA Normal).

Unless this was the initial test, that is.

Surely (and as has been mentioned in earlier posts) the "correct" approach is to establish which particular Standard appertains to the equipment in question, and then apply it!

thanks for the reply... but i still confused, which standard should I used. or can anyone give me a copy of the detail about every standard that can implement to medical equipment.... i want to learn about it..

We're all waiting for the experts to deliver, Mammad.

But meanwhile (whilst we're all growing older), check out these articles, and this link.

thanks Geoff.. its very helpful..
I just want to asking, which standard are u used in ur site?

You're really asking the wrong bloke, Mammad (as I don't have a job-site, as such).

But, back in my contracting days I usually inserted wording something like:-

"The highest international standards, or any standard preferred or specified by the client" ... which I still reckon is fair enough.

But, if you're asking me for a recommendation ... I would go for 62353 (on the grounds that it's aimed at routine maintenance, rather than manufacturers).

If yours is connected to permanent ac source which is electrically so connected that the connection can only be loosened with the aid of a TOOL then it actually passed the leakage current test (these limits are specifically stated in IEC60601-1 standard). The limits are 5mA (NC) and 10mA (SFC). Hope this answers your query.

ok geoff... thanks...