EBME Forums Forums Maintenance Technical Assistance Newbie help with Electrical safety testing

Hello members I’m relatively new to Medical equipment but have a background in electronics repair. I’ve attended an electrical safety course run by an external firm but in truth I thought it was poor and not well explained. I did raise questions but didn’t feel they were answered adequately. I have decided to ask the experts on here. I understand the differences between type testing IEC 60601-1 and the less stringent IEC 62353 but there are areas of the 62353 I’m struggling to comprehend fully and would like to make sure I’m doing things correctly.
Firstly 62353 tests earth continuity which I’m OK with
Insulation tests I’m OK with too.
For the equipment current and leakage tests what and how is it being measured? Does the tester require the earth lead to be connected to any earth or in-earthed conductive part or is the current measured internally in the tester between the earth, negative and live connectors? Also same question really for patient applied parts is the earth lead necessary or does the tester test between the conductors internally? Lastly Class 2 equipment on the equipment current and leakage tests is it necessary to have the earth test lead connected to any non earthed conductive part? Also on class 2 equipment I understand the use of foil on non conductive parts but is that actually a thing as I’ve not seen more experienced colleagues do it and when asked I’ve been told it doesn’t matter as the AP is plastic rubber etc?
Sorry it’s a long post but I’d like to know what I’m actually testing rather than letting the tester automate it to the point I’m just pressing a button not knowing what it’s actually doing. Btw the tester in use is a Fluke ESA 615

Welcome to the forum, Karl.

This stuff has been worked through a number of times on this forum. You could look up some of those earlier threads if you have the time.

For instance (seeing that you mentioned "foil"):- this one.

But first I suggest that you go through the articles offered here ... and here - then come back with any questions you may then still have.

Meanwhile, I'm interested in your comments about the quality of the course you attended, and can't help but wonder who the "external firm" was. You had better not name them in open forum (PM me if you like). Either way, were you able to offer "feedback" at the end of the course?

Hi Mate,
Please see the attached links that sheds light into Electrical Safety Testing on Medical Equipment:
https://www.ebme.co.uk/articles/electrical-safety
https://www.rigelmedical.com/gb/sup...sting/18-a-practical-guide-to-iec-62353/

Hi Manoj thanks for your help. I’ve downloaded the Rigel guide and it’s been very useful. I’m a little confused over a couple of things though and would like clarification if possible. For Class 2 insulation tests it states you need to use an auxiliary cable to the enclosure us g tin foil if necessary. I understand this OK but later on for the Class 2 current leakage tests does this cable still need to be attached? In the diagram there is a cable shown going to the enclosure so I’m thinking it does. It says all applied parts and enclosure are tied together and current to earth is measured. On Class 2 equipment where is it measuring to if for example the earth pin is plastic in the plug top so there’s no connection to the earth inside the tester? Is it done via the auxiliary cable? I’ve attached a picture with the two areas circled. Hope this makes sense but if not please let me know so I can try and explain a bit better. I’m just not comfortable selecting a sequence on a machine and not knowing what and how it is measuring and conducting the tests and really want to know what it’s doing. Thanks

The answer is right there in the document (and, by the way, also here).

"All applied parts (B, BF & CF) and grounded (e.g. enclosure class I) and non-grounded accessible conductive parts or non-conductive accessible parts (enclosure class II) are grouped together and connected to the ground via the 1kΩ measuring device (body model)."

In practice, you may have a problem deciding upon a "non-conductive accessible part" on Class II equipment, but your test instrument (Fluke or whatever) will be connected to PE (as the diagram shows). But the diagram clearly shows a test lead connected to the enclosure, so it's up to you to do that (however futile that may seem in terms of Ohm's Law).*

Frankly, I would not worry about that particular test too much ... after all, what magnitude of current readings are you expecting anyway? If the Class II equipment is electrically unsafe, that will become apparent in other tests ... especially if you can find a conductive accessible part on the enclosure (as required by the insulation tests).

Here is a tip:- if you really want to understand EST, you need to look closely at the various circuits. They actually tell you all you need to know ... and the Rigel guides illustrate them most clearly. Didn't the course you took spell that out? But don't worry, there aren't that many, and they should be easy enough to learn.

* I think this is where the "foil" technique comes into play. I have seen folk use an old ESU return plate and sit the Class II kit on that (at least that way the flying lead has something solid to clip on to). Opinions on the efficacy of that idea seem to vary, and you may find life becomes easier if you simply adopt whatever your mates do in that regard.

In short, I think confusion arises over the need for a "conductive" enclosure for insulation tests, and a "non-conductive" enclosure for leakage tests of Class II equipment.

In the first case, the Rigel guides (and some other sources) do indeed mention the need to "wrap the enclosure in aluminium foil" and connect the flying lead to it ... but is seemingly silent in this regard for the second case (leakage tests).

I don't have to hand a current copy of the 62353 Standard, but hopefully someone may be able to tell us what it says about "foil" and so forth.

I have just taken a look at the user manual for the Fluke ESA-615. It looks like a nice piece of kit.

However ... although the manual shows some nice clear diagrams, they do not all correspond directly to those we have been discussing. Indeed, the manual does not seem to care much about Class II specifically, at all.

All the diagrams show a Conductive Part at the enclosure casing of the DUT, and I note (and endorse) the terminology used:- "non-earthed accessible conductive point(s)". But, as we know, such are often (usually) not found on Class II (that is, double-insulated) equipment.

I also note that some of the tests described in the manual apply only to 60601 (and not 62353) whilst others apply only to 62353 etc.

By the way, do you use any of the Test Sequences?

PS: the only EST manual I have come across that mentions "foil" is that for the Rigel 288.

Thanks Geoff & Manoj I understand it now fully. In answer to your question yes I do use sequences and occasionally have to create a sequence. It's very convenient and on rapid setting it is very quick but I wanted to know exactly what was being measured and how. It's all clear now though thanks I'm much more confident in what the tester is doing during the automated tests.