Can I draw your attention to an article in Spring Issue of Switchedon, published by the Electrical Safety Council.
It warns of the danger of the usual plug-top charger, that you find everywhere these days. They tested ten samples obtained from various suppliers, and found that all ten failed the safety tests
The article says that 1.8 million were bought in the UK last year, and they are produced in Hong Kong for 3p each!
If you have bought any of these,particularly if they are to be used in medical locations, you might not get what you expected.
It seems that even CE marked devices can be dangerous!

Hi Bam

Can you elaborate on the problem/s they found?

btw - I've heard the referred to as "wall warts" partucularly by guitarists!

Mick

Unfortunately the article is not available on the web, only in print, which is not helpful
It states that 3600 chargers have been seized from retailers over a 6 - 8 week period.
It was found that typically there was insufficient insulation between live parts and between input/output circuits
This could result in the output reaching mains voltage.
A number of other faults were found, and it is suggested that you should not assume that because the device is CE Marked it is safe to use, due to lack of control over CE Marking.
There is a similar article on the MHRA web site, to find it go to www.mhra.gov.uk then type "switch-mode" into the search box in the top right hand corner.

One big problem is the IET code of practice for PAT testing non-medical devices only indicates to conduct visual checks on class II devices. This means no routine safety testing is conducted so we have no idea how big the problem is.

Even if the COP was changed, another problem is that most of those involved in PAT testing don't know how to test these devices properly.

They think wrapping some foil around the plastic case and conducting an insulation test between the mains pins and the foil is a good test!

They never think that the user will touch the metal (low voltage) output plug or metal chassis of the laptop it connects to and therefore it might be a good idea to test the insulation between the AC pins and output pins! (Ideally using an AC leakage test and not a DC test to ensure you get a true idea of the potential leakage.)

First of all (and as I have said before) ... forget (that is, ignore) CE marking. In practical terms, it means nothing. You can buy rolls of CE stickers, and stick them on yourself if you want.

Secondly, yes ... "wall warts" are junk, electrically (safety) speaking. But, who is at risk here? The patient? I don't think so. The user then? Yes, perhaps.

But (unless I've lost the plot, and failed to keep up ... both of which are quite likely), I believe that the stringent low values of allowable leakage currents applicable to the various classes of medical equipment (with which we are all familiar) are there to protect patients in electrically compromised situations (that is, when natural defences have been breached), as when in direct electrical contact (for purposes of examination or therapy), or when undergoing surgery, with electrodes poking about within the body, in an anaethetised state, etc., etc.

So let's not get too excited about the 3p "charger" ("adapter", whatever). What are you going to do ...bin them all? [yes ... good idea]

And ... what about all the clearly "non-medical" ones seen every day in any hospital? All the "personal stuff" ... like mobile device chargers and all the rest? How about going around and cropping the leads off just where they exit the "charger". H'mmm. That should get the owner's attention!

Not being one to "disrespect" the NHS (for example) ... surely hospitals have some sort of policy about all this?

Personally, if I was doing the rounds on an electrical safety mission, I would assess each bit of kit as I found it. My reaction would depend upon where the thing was, what its purpose was, and what else was supposed to be going on there. If it was owned by someone other than the hospital (and I thought it presented some sort of risk), I would "have words" with the owner. If it was something outrageous, I would destroy the thing and chuck it in the bin. How's that for a Policy Guideline?

Like the Retailers (and worms like Estate Agents) like to say, it's all about "Location, Location" ... and, er "Location".

One last thought ... if the laptop (etc.) user is happy enough to accept the "risk" (or, more likely, crack on in blissful ignorance) of using the laptop (etc.) at home, with all the attendant "accidents waiting to happen" there (spilled coffee comes to mind) ... need we make a fuss about the same equipment being used in the hospital? Well, unfortunately, yes ... "duty of care" and all that. And third parties (injured parties, even) are likely to be involved. So ... surely we (the management, someone) has the right to require that no unsafe junk be brought within the hospital from outside.

Again ...location:- office environments :: OK. "Medical" environments (define) :: keep the junk out. Discuss (actually, it's an important issue) ... similar to the perennial "extension lead" problem!

Some good points there, Geoff. I think at least some of the issue comes down to successful education. I have had, over the years, quite senior medical people basically saying 'what's wrong with that, it's OK at home'? My reply has usually been along the lines of 'true, but when was the last time you carried out major invasive surgery at home on your kitchen table'? Of course, they commented that it would be a totally inappropriate environment (for 1st world locations at least), to which I said 'and so this hospital environment is inappropriate for this 'home' electrical device'! It seemed to get the point home!

Of course in developing countries such as where I am now, it's difficult (and perhaps counter-productive) to be quite so strict. Sometimes of course, the environment is so 'bad', that it's even MORE important to be strict about certain patient-safety issues. Surely, that's what part of our profession is about; knowing what really IS important in any particular situation, with often conflicting needs existing simultaneously?!

People who make the rules might like to think about colour coding.

You know, have "home use" equipment painted Day-Glo Orange ... then ban such devices from entering specific areas of the hospital ... on pain of meeting the guy with the side cutters!

Another "solution" could be yet another stick on label:-

Not for use in Patient Areas

... or some such thing (again, on pain of seeing it ... er, taken away)!

So ... when doing the rounds, if you come across objectionable kit that lacks your regular asset/PM/green dot/date (whatever) sticker, or no label like that above ... it's "Heigh-Ho, Heigh-Ho ... and in the Bin We Go"!

By the way, what is the allowable insulation and leakage criteria for these things (both in the home ... and in the "patient ennvironment" where applicable and/or necessary)?

Let's have Chapter and Verse (which Standard, what figures, how should we test - if at all), please.

And (here's a teaser for you all whilst I'm out) ... if such junk has to be used in, say, the operating theatre ... would plugging them in to a medical isolation transformer render them "safe"?

I don't think that the actual leakage current on some of the chargers tested matters too much, in many cases the output voltage was at about the mains input voltage, since the only separation between the input and output was the enamel on the copper wire!
You would expect the leakage current on a 60601 compatible charger to be less than 10 microamps, but if you cannot trust the CE Marking, you might just as well buy the cheapest available.
To test the charger I would suggest that you plug it in to the normal mains supply, and then measure the voltage between earth and either side of the output using an autoranging DMM. In most cases the output voltage will be less than 12 volts DC, so it does not matter which side of the output you measure.If the meter reads 100 volts or more, then stop there, but if you are getting a reading of just a few volts, then it should be safe to switch the meter to the AC current range. If there is any likelihood of the patient that is using the device being supplied by the charger having a catheter inserted into the central circulatory system, then anything greater than 10 microamps would be dangerous.
It would not really help to use an isolation transformer. If you measure the current between either side of the transformer secondary and earth you will find that it is much more than 10 microamps!

Who is the Electrical Safety Council? What weight do their recommendations have?


What tests were these, I wonder?


Do they say what what they regard as an acceptable figure for insulation?

It sounds to me like we're actually talking about macro shock (rather than patient related micro shock) hazards here. Just as (potentially) deadly, of course, but dare I suggest that a different set of "duties of care" may apply?

Surely the Bottom Line here is to (whilst forgetting about CE marks) only permit chargers (adaptors ... call them what you will) with certified 60601 approval into any "medical area"?

This is what the Electricity Safety Council have to say about themselves:


Who are we?
The Electrical Safety Council (ESC) is an independent charity committed to reducing deaths and injuries through electrical accidents at home and at work.

We are supported by all sectors of the electrical industry as well as local and central government and work to promote safety and good practice.

The power supplies were checked by an independent test house against the standard claimed by the device. My concern is that it seems that I cannot trust the CE Marking, and really need to test these things my self to remain in the clear. What about the ones that are brought into hospital by patients? Do you ban them, test them, get the patient to sign a waiver? The article that I quoted includes the story of a four year old boy killed by the power supply that he was using on his Play Station. Who would carry the can if this happened in your hospital?

Ye Gods ... this is getting worse (as in, more interesting)!

Killed by his PlayStation (power supply)? How? When he spilled his orange juice all over it? Or did he stick it his mouth?

Wasn't it (Dickens') Mr.Gradgrind who said something like:-

"I deal in facts, Sir, facts"!

[Afternote]:-

And how many hospitals have PlayStations (and similar) on the Asset Register, I wonder? Or, for that matter, on the Risk Register?

There is always risk ... like everything else, it just has to be managed.

I managed to find the link to the publication so that you can read it all yourself:
http://www.esc.org.uk/business-and-community/our-magazine.html

Well played, Sir!

Something to read later on, with my cocoa, then.

Interesting article as it supports what I was saying about inadequate testing being conducted on these class II plug in power supplies and chargers!

Although I suspect only doing a Hi-Pot (flash) test between the mains input and low voltage output connections would actually revel a problem. Some domestic PAT testers support this 3KV AC test but better to perform at DC to reduce damage caused by high leakage currents when using AC. The GMC Secutest SIII springs to mind as a unit that can perform the DC Hi-Pot tests and is a nice medical safety tester.

Create a problem, more like.

Let's stick to whatever it is the Standard(s) call for, shall we?

That is IEC-60601-1 et al. With emphasis (I would suggest) on IEC 62353.

Next thing we know we'll be back to "mains on applied parts". You know, 220 VAC on iPod earphones!

PS: I've not had time to read the article yet (and I'm out of cocoa).

My main concern is that it seems that you cannot trust the CE Marking, since it is possible for a manufacturer to market a product which is significantly different to the one submitted for test. I thought that the whole point about CE Marking was that we did not have to retest every product!
Now I am going to have a coffee!

I have already offered my opinion on CE marking. I feel much the same about all stick-on labels. Why should I trust any of them?

The only thing I trust is my multimeter (if you catch my drift), and I would urge all techs to adopt a similar outlook. In fact I believe (hope, even) that the majority of techs already feel the same way.

As I am seemingly never tired of saying (and as we all know), electrical safety is the core raison d'être of "biomed"! And (as the Guardian of electrical safety in hospitals) we must be ever vigilant.

Enjoy your coffee, Brian. But just be careful with that kettle! That is, is the tingling sensation due to the caffeine ... or something else?

Specifically on these plug-in chargers or power adaptors, I showed one to our manager some years ago which is appearing more and more in medical settings.

It is a power adaptor with interchangeable sections for the various world-wide pin designs. This would be great as an elegant solution, if the interchangeable bits were not made of cheap and easily snapped plastic, and the contacts that dock them onto the charger were not exposed.

When (note - not IF! there is form here) they break, this leaves two large copper contacts attached to the live mains in the wall ready for anyone to electrocute themselves on. And this device has a CE mark and BS kitemark.

My manager tried to raise a report with the MHRA but they simply were not interested.

Well if the medical location was to the MEIGaN standard then at least the RCD would trip (or in the case of an IPS then a shock would be unlikely).

It is always amazing that in new houses we now have to have RCD protection but I see few new hospitals install RCD protection on the mains sockets!

The official advice from the MHRA is that adaptors, multi-plugs and extension mains leads should not be used in a medical location. Sufficient, conveniently located mains sockets should be installed.
The 17th edition of the IEE Regs requires RCDs to be installed in all final circuits. The RCDs should be tested QUARTERLY!
I have yet to encounter anyone who does this.
And I thought that the tingle in the coffee was due to something in the water!

So. Do doctor's surgeries and health clinics count as medical locations? These are the precise places where these easily damaged adaptors are in use.

A large percentage of visitors take their children with them - after all it is usually the children who need the doctor's care. It is almost guaranteed that if there is a damaged adaptor within reach, a small child will be sure to find it.

I doubt that the RCD tripping would prevent an actual shock being given. It would just limit the length of time the mains was attached to the unfortunate victim.

Quarterly testing? What happened to making risk assessments to find a reasonable scheduled interval? After all, RCDs are a fixed system and unlikely to suffer the sort of damage that a mobile piece of equipment could be subjected to. And most movable equipment is tested less often than that!

... but on the other hand:-


OK ... so let's just follow (that is, enforce) the Official Advice, shall we?

And ... why are we talking about RCD's here?

The saying about "singing from the same hymn sheet"* comes to mind? As does the one about stable doors and runaway horses.

* Selected deliberately to rattle non-believers.

"So. Do doctor's surgeries and health clinics count as medical locations? These are the precise places where these easily damaged adaptors are in use."
Exactly! But these are not damaged, they are built that way. I think that we should "encourage" the Electrical Safety Council to do something. I intend to try, anyone like to join me?

Nice sentiment Brian. But the ESC will do nothing but "lobby" at best, and "wring hands" at worst.

They have no bite ... unlike, that is, my side-cutters!

Some of us have been in this game long enough to have learned (a very long time ago in my own case) that:-

"If you want something doing, you are better off doing it yourself"!

Or, as John says:- proactive, rather than inactive (or something like that)!

Remember what I said about the Guardians of Electrical Safety? That's us. In real (practical) terms, the buck stops here (with us). There is no-one else.

Having just gone through the article in question, frankly I see nothing new (or surprising) there. But that "Charger supplied" doesn't look to me like a "bent pins" situation ... but rather an adaptor suited to mains outlets used in parts of China (and very similar to those found in Australia).

That in itself highlights the main point (that I believe is) being made. That is, that buying stuff off the internet bypasses the many regulations and consumer safeguards that ordinary High Street retailers have to comply with.

So ... what can the Electrical Safety Council (or anyone else) do about that? Nothing (as I have already mentioned).

As I have said before, it is up to those of us who carry the Burden of Competence not to shrink from our duty of keeping our eyes open as we do the rounds ... and not to be timid about taking any action necessary in dealing with offenders (that is, not only the dangerous junk itself, but also the irresponsible idiot who brought it in, placing others in harm's way).

Yep, the "charger supplied" is the standard Australian pin config.

Apparently it only varies from the Chinese one by a small difference in the length of the pins.

I wonder why Oz didn't adopt the UK's style - which would have been the round pinned 5 Amp, 15 Amp etc. type "back then" - and later on the UK BS-1363 "13 Amp" type.

After all, when you have a "new country" (largely free of industrial legacy), you may as well go for the best!

They would be classed as medical locations if medical electrical (60601) equipment is being used. (See MHRA MEIGaN document or IEC 60364-7-710)


An RCD will trip before an individual can receive a fatal shock (within 40mS at 30mA).


An RCD is a mechanical device and when not operated for extended periods can suffer from sticking or delayed action so the device fails to trip at the required values. Regular testing ensures the trip will operate correctly when needed! (Just pressing the test button is all that is required 4 times a year.)

Here's an interesting article which some may have missed.

Note the clever use of "crowbar circuitry" mentioned at the bottom paragraph!

Meanwhile (following Brian's earlier advice), sales of "Voltsticks" have now soared. I know that I certainly carry one!