EBME Forums Forums Maintenance Test Equipment IEC 62353

Could anyone please clarify is IEC 62353 accepted for use in the UK?

Yes it is certainly accepted for use when routine testing and for testing after repair in the UK. However, this is not to imply that it is in anyway mandatory.

And, as BS EN 62353:2008, it gets an honourable mention in recent "guidance" from the MHRA ("Managing Medical Devices" - April 2014).

Although there were some minor objections in the national forward of the 2008 version of BS EN 62353 these have now been resolved as indicated in the national forward of the 2014 version:


It is not only advisable to use this standard for testing, as it is the only official standard, but can save lots of time, especially if the Alternative leakage current test methods are used.

BS EN 62353 is also good for tests before putting devices into service. From section 4.1:

– tests before PUTTING INTO SERVICE,
– RECURRENT TESTS, and
– tests after REPAIR.

Yes; I think we can all agree that 62353 is the Standard that everyone should be using these days.

But out of interest, Mike ... do you have any idea about what those earlier UK objections were? Something nebulous ... or something of real (practical) substance?

In my view they were unjustified objections largely based on a misunderstanding of the Alternative leakage method and a wish to carry on using 60601 tests. Actually everything is now possible according to the latest 62353 but I would urge all those performing EST to consider switching to 62353 and mainly use the Alternative methods. No need for DC insulation testing either! 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 and no need to do any mains reversal. Quick, reliable and easy!

I can well imagine that the Alternative Method is not easily understood (and I wonder how instructors on electrical safety courses get on in that regard).

In fact some may even go as far as to suggest that it's a bit of a "fudge"!

Although I can see the attraction to using the Alternative Method (in short:- "quick and easy"), I would argue myself that it doesn't actually measure leakage currents at all, but rather estimates (and usually an over-estimation at that) what they might be!

Biomeds of the type who prefer things like EST to be Step 1), Step 2) etc. (that is, simplified) may not be too happy about having to choose between the three approaches ("Methods") that 62353 supports - and my guess is that the (more traditional) Direct Method is the one most techs will be following (as it is easily understood, and "follows on" from what folk have been used to - in other words, 60601).

Lastly, it is my understanding (?) that in cases where the Alternative Method indicates currents around the edges of acceptable limits (or above them), then 62353 suggests using another Method (eg, Direct) to confirm them!!

Maybe we need a Poll (and we haven't seen one in a while) to find out what the various Departments are doing when it comes to 62353.

BTW: have the Standards Committee(s) made up their mind yet about what the Protective Earth Test Current should be?

No, it measures the leakage currents very accurately! But you have to understand the reason for the higher values than when using the Direct test method. Essentially the Alternative test is the same as performing an open neutral 60601 Direct leakage measurement, when it is normal to expect about twice the standard leakage current. Remember in a normal Direct test we have a T-NS mains supply in which the Neutral is referenced (connected) to Earth. Therefore generally half the capacitance that makes up the leakage currents have no potential across them, whereas when the Neutral is open the full mains supply is presented to all these capacitances. This is why both the open neutral 60601 tests and 62353 Alternative method allow twice the leakage values (1mA instead of 0.5mA).

The reason 62353 mentions you have to measure using another method if the measured Alternative method exceeds 1mA (or 2mA for mobile X-ray units) is this indicates the earth leakage leakage current may be at the 60601-1:2005 5mA level so this requires the touch leakage to be measured to ensure it is below 0.5mA.

From 62353: If the value of the alternative method exceeds 1 mA, either the direct method or measurement of the TOUCH CURRENT shall be applied (allowable values in Table 3).

One you switch to using the Alternative method and have reference values, as you need for all 62353 tests anyway, you can rest easy in the knowledge you have performed adequate safety tests to meet any legal obligations and saved time and money in the process!

As for your last point the choice of protective conductor test current is up to you, anywhere between 200mA and 25A. But it is generally accepted the lower figure is the one least likely to cause damage if an incorrect point is touched and therefore would be my choice every time. Better a false failure due to an oxidised contact than generating a potential fault by using 25A!

Accurately measured, maybe; but how can they be the true (actual, real world, "as they would be in use") leakage currents if the kit being tested is not energised by the mains?

Don't get me wrong, I'm a supporter of 62353 in general, but I can't help but think that it's a bit of a "missed opportunity". In short, there's probably too much "mix 'n' match" (or "take your pick") in there for many of the biomeds I have come across; most of whom seemed to prefer a "this is what you do" approach.

I cite your final revelation as an example ... so, even after forty-odd years of EST Standards, we still can't agree on the test current. Let's plumb for 10 Amps and be done with it!

Perhaps next time around we can get the Committee(s) to consider a "62353-Lite" ... one that ditches the possible confusion (complications) of the Alternative and Differential* Methods, and declares what the PEC test current should be.

* When would (could) you use it? It's "quick and easy", and measures total leakage current - but can't accurately measure low values of leakage (which is, after all, what we're hoping for)!