EBME Forums Forums Maintenance Test Equipment IEC 62353

Mike suggets "So on a class I device only three electrical tests, Protective Earth Resistance, Alternative Equipment Leakage, Alternative Applied Parts Leakage. No need to power up (boot) the device". In all the years I have done electrical safety testing we have always been instructed to have the unit under test powered ON when carrying out an electrical safety test. Is it now standard practice guided by IEC62353 that this is no longer a requirement?

Only if you (or your boss, Department, company, organisation etc.) elect to use the Alternative Method.

I can only wonder if all this choice (about which Method to go for) is just going to end up with different hospitals adopting different procedures. As far as I'm concerned, the "jury's still out" as to whether this is really "progress".

Here's a question:- do the three 62353 test Methods have equal value? Or are some Methods "better" than others?

And lastly (as I have mentioned before), I see a need now to always record (on the test sheet, in the database and WHY) which Method was used. Note that 62353 calls for measurement results (and the Method used) to be documented anyway; the Standard calls these the "Reference Value".

If you do not power on a device you are only testing as far as the on/off switch. For example, if the live after the switch was attached to a patient lead you would get no applied part leakage so the equipment would pass the test. But I would not fancy getting attached to a piece of equipment where the applied part becomes live as soon as you turn it on.
To my mind testing equipment without powering it on is a nonsense.
Robert

Mike's not going to be happy with that, Robert!



What if you switch on ... but still haven't plugged into the mains? Wouldn't you then be testing as Mike described a couple of days ago?

(BTW: for the "purposes of debate", I'm just playing Devil's Advocate here; I have no particular axe to grind apart from a preference for simplicity, common sense, practical, valid, purposeful, and "real world" testing of the kit)!

I can see the logic in Rojos point, and in practice I see large differences in leakage current measurements between the device being powered off and on, personally I would think it pointless measuring leakage currents from a device that is not powered on. The interesting thing is, there is still many differences of opinion in interpretation from highly experienced technicians on how to routinely test electro-medical devices. Why should this be the case after all these years, personally Ive given up trying to figure it out as it seems to be a matter of opinion depending on where you work.

Yes ... but that would be using the Direct Method (or a 60601 testing regime), I should imagine.

Maybe the best "way forward" is to adopt 62353, but (for the time being at least) stick to the Direct Method of measuring leakage current.

Regarding your second point:- yes, I agree.

Geoff, I honestly had not heard of this alternative method. I am even afraid to ask what it is as I can imagine there is another wave of confusion coming my way. The only saving grace is I know Im not alone, having asked another 3 experienced techs if they know what this alternative method is, I was met with 3 blank expressions.

OK, but 62353 has been around for a number of years now.

Although (as mentioned before) my aim here is simply to "continue the discussion" (and I believe it is one that needs to be discussed), I do wonder why the committees of electrical safety Grandees felt the need to introduce the extra (both the Alternative and Differential) testing methods. Where did the "push" come from? Certainly not from the "shop floor", as far as I can tell.

On the other hand, the Alternative method may be useful for testing PC-based kit (not energised [no "boot-up"]) such as ultrasound units, lab analyzers and er, PC's; whilst the and Differential method may be useful for "heavy current" kit such as mobile x-ray units and so forth.

I have linked to this article by John Backes before. It gives a good precis of the stuff we have been discussing. It is a bit old now, so if anyone can link to a better one, feel free to go ahead!

This .pdf also offers some clues about which Method to apply.

Oh yes, dont get wrong Geoff, I am aware of the existence of 62353 and I recall our department was given a talk about this when it initially came out about 8 years ago. But after intial discussions and then waiting on definitive changes to our Procedures it seemed to fall by the wayside, so no one in our dept has changed their method of electrical safety testing. Ive had a quick look online and I see what you mean about the different methods, direct, differential and alternative, but alas it is not even on the radar among the techs in our dept.

I believe (hope?) that manufacturers' documentation and (or) service manuals should clearly declare which 62353 testing Method is appropriate and recommended for each piece of equipment ...

... failing that, it would be nice if some Learned Fellow came up with such a list to cover typical examples of equipment normally encountered in hospitals these days.